#Mpox - cMulti-country external #situation #report no. 64, published 26 March 2026 (#WHO, summary)

 

{Excerpt}

Highlights

• Transmission of mpox continues mostly within sexual networks, affecting both women and men, followed by household transmission, and in some historically endemic areas, affecting all age groups. 

- All clades of monkeypox virus (MPXV) continue to circulate. 

- Unless mpox outbreaks are rapidly contained and human-to-human transmission is interrupted, there is a risk of sustained community transmission in all settings. 

• In February 2026, 46 countries across all WHO regions reported a total of 1184 confirmed mpox cases, including four deaths (case fatality ratio [CFR] 0.3%). 

- Of these cases, 58.6% were reported in the WHO African Region. 

• Four WHO regions – the Region of the Americas and the African, South-East Asian and Western Pacific regions – reported a decline in confirmed cases in February, compared to January 2026, while the European Region reported an increase in confirmed cases. 

- The Eastern Mediterranean Region reported the same monthly case count in January and February 2026.

• Seventeen countries in Africa reported active transmission of mpox in the last six weeks (1 February – 15 March 2026), with 907 confirmed cases, including seven deaths (CFR 0.8%). 

- Countries reporting the highest number of cases in this period are Madagascar, the Democratic Republic of the Congo, Kenya, Burundi, and Liberia. 

• Three countries, Argentina, Austria, and the Central African Republic, have reported mpox due to clade Ib MPXV for the first time. 

• Outside Africa, community transmission of clade Ib MPXV continues in the WHO European Region, with Austria, Belgium, Portugal, Spain, and the United Kingdom of Great Britain and Northern Ireland reporting community transmission, including in sexual networks of men who have sex with men.  

• This report provides an update on mpox outbreak transmission dynamics across different clades and settings. 

• On 7 April 2026, World Health Day, WHO will join a One Health summit convened by the Government of France. 

- The Summit will foster international and interdisciplinary dialogue to highlight the interdependence of human, animal, plant and ecosystem health, and the need for coordinated, science-based approaches to address shared health threats, including for emergency response. 

(...)

Source: 

Link: https://www.who.int/publications/m/item/multi-country-outbreak-of-mpox--external-situation-report--64---26-march-2026

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Rapid #risk #assessment, acute event of potential public health concern: #Diphtheria, #Africa Region (#WHO, March 20 '26)

{Summary)

Risk statement

-- This WHO Rapid Risk Assessment (RRA, v2) aims to assess the risk of diphtheria at the regional level, considering the public health impact, the risk of geographical spread and the risk of insufficient control capacities with available resources. 

-- Diphtheria is a major public health problem in the WHO African Region (AFR) despite significant efforts on immunization in the past decades (e.g. introduction of DTP vaccine in the Expanded Program on Immunisation in 1974). 

-- Between 2000 and 2024, 75 789 diphtheria suspected cases were reported across the Region with an average 3 500 cases per year.    

-- Between the beginning of 2025 and as of 1 March 2026, over 29 000 suspected diphtheria cases with 1 420 deaths (CFR 4.9%) have been reported across these eight countries: Algeria, Chad, Guinea, Mali, Mauritania, Niger, Nigeria and South. 

-- This represents a 67% increase in the number of suspected cases (11 749 additional cases) and a 59.4% increase in the number of deaths (529 additional deaths) reported since the last WHO RRA (v1) conducted in October 2025, Nigeria continues to account for the majority of suspected cases (62.6%) and deaths (66%) in the Region. 

-- Of the 18 130 total confirmed cases (clinically compatible, laboratory-confirmed and epidemiologically linked) across the eight affected countries, 752 (4%) cases were recorded as laboratory-confirmed: Algeria (8), Chad (1), Guinea (48), Mali (66), Mauritania (12), Niger (313), Nigeria (211) and South Africa (93).     

-- Case data trends from 2026 have been difficult to interpret, with extremely delayed case reporting from countries (both to the national and regional levels), and instances of under-reporting also being notified, particularly from humanitarian settings. 

-- However, a lower number of cases are being consistently reported than earlier in the outbreak and thus it appears that new cases continue to decline or plateau, as seen in half of the affected countries (Chad, Mali, Mauritania, and Nigeria).    

-- Since the first WHO RRA (v1) conducted in October 2025, the regional CFR remains around 5%. 

-- While Guinea continues to report among the highest CFRs in the region at 19%, South Africa’s CFR has increased since the last WHO RRA (v1) to 19%.  

-- Children aged 5–14 yrs (57%) and females (63%) are the most affected; where information is available on the vaccination status of cases, most cases are unvaccinated, under-vaccinated, or with unknown vaccination status.   

-- While the overall risk was previously assessed as “HIGH” at the regional level in October 2025, it is now considered “MODERATE” due to:  

• Overall declining trend in number of weekly cases regionally, with country-specific trends also declining in half of the affected countries (Chad, Mali, Mauritania and Nigeria), and only sporadic cases reported from South Africa. 

• Strengthened coordination of public health response through the activation of an Incident Management System (IMS) in most of the affected countries. A joint Regional Office for Africa (AFRO) and WHO headquarters (HQ) IMS structure was activated to support the regional coordination of the response, with high-level ministerial commitment to controlling the outbreaks in the affected countries.  

• Implementation of immunization activities as part of the outbreak response in most of the affected countries. 

• Strengthening of surveillance, case management, community sensitization, through capacity building activities, and the provision of diphtheria antitoxin (DAT), antibiotics, laboratory supplies, etc.  

-- Nonetheless, some challenges continue to prevent the effective containment of these outbreaks:  

• The complex humanitarian situation in many of the affected countries continues to contribute to poor access to immunization and healthcare services for internally displaced persons (IDPs), nomads, miners, and migrants. Unsanitary living conditions (in displacement camps) are also favouring the transmission of diphtheria. These increase the exposure risk of vulnerable groups (particularly women and children) to diseases.   

• Limited laboratory confirmation due to lack of reagents, sample transportation challenges and limited available of laboratory capacity.  

• In most of the affected countries, the annual coverage for routine diphtheria vaccination remains below the national targets thereby contributing to the resurgence of cases and outbreaks.  

• Global scarcity of DAT for the treatment of affected persons. 

• High internal and cross-border movements of susceptible individuals (unvaccinated or not fully vaccinated). 

• Persistent funding challenges across most affected countries exacerbated by the current challenging international funding landscape.  

-- The overall risk at the global level remains ‘’LOW’’ due to: 

- The global risk of diphtheria outbreaks from the ongoing multi-country diphtheria outbreak in the African region is assessed as low, given the existence of routine immunization programs in most countries. 

- Nonetheless, the risk posed by international travel of susceptible populations from the WHO African Region cannot be overlooked, highlighting the need to strengthen risk communication, demand generation and reactive immunisation, as well as the need for enhanced data sharing and surveillance globally. 

(...)

Source: 

Link: https://www.who.int/publications/m/item/who-rapid-risk-assessment---diphtheria--african-region-v.2

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Early #Detection and #Surveillance of the #SARS-CoV-2 #Variant #BA32 — Worldwide, November 2024–February 2026 (US CDC, MMWR, March 19 '26)

 

Summary

-- What is already known about this topic?

- CDC tracks SARS-CoV-2 variants internationally using digital public health surveillance and in the United States using genomic surveillance, including wastewater and traveler-based surveillance. 

- The highly divergent SARS-CoV-2 variant BA.3.2 was first detected in a respiratory sample collected on November 22, 2024, in South Africa.

-- What is added by this report?

- As of February 11, 2026, BA.3.2 had been reported in 23 countries. 

- Detections began increasing in September 2025. 

- In the United States, BA.3.2 was detected in nasal swabs from four travelers, three airplane wastewater samples, clinical samples from five patients, and 132 wastewater samples from 25 U.S. states.

-- What are the implications for public health practice?

- Monitoring the spread of BA.3.2 provides valuable information about the potential for this new SARS-CoV-2 lineage to evade immunity from a previous infection or vaccination.

Abstract

The SARS-CoV-2 variant BA.3.2 was first identified in South Africa on November 22, 2024. BA.3.2 has approximately 70–75 substitutions and deletions in the gene sequence of the spike protein relative to JN.1 and its descendant, LP.8.1, the antigens used in the 2025–26 COVID-19 vaccines. CDC is using a multimodal SARS-CoV-2 genomic surveillance approach to monitor the emergence and spread of BA.3.2 and other SARS-CoV-2 variants internationally and within the United States. The first U.S. BA.3.2 detection occurred on June 27, 2025, through CDC’s Traveler-Based Genomic Surveillance program in a participant traveling to the United States from the Netherlands. The first U.S. detection of BA.3.2 in a clinical specimen collected from a patient was reported on January 5, 2026. As of February 11, 2026, BA.3.2 had been detected in voluntarily self-collected nasal swabs from four U.S. travelers, clinical samples from five patients, three airplane wastewater samples, and 132 wastewater surveillance samples from 25 states. BA.3.2 has been reported by at least 23 countries. SARS-CoV-2 continues to cause substantial morbidity and mortality worldwide. BA.3.2 mutations in the spike protein have the potential to reduce protection from a previous infection or vaccination. Continued genomic surveillance is needed to track SARS-CoV-2 evolution and determine its potential effect on public health.

Source: 

Link: https://www.cdc.gov/mmwr/volumes/75/wr/mm7510a1.htm?s_cid=OS_mm7510a1_e&ACSTrackingID=USCDC_921-DM153709&ACSTrackingLabel=Week%20in%20MMWR%3A%20Vol.%2075%2C%20March%2019%2C%202026&deliveryName=USCDC_921-DM153709

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#International #food safety event: #Infant #formula and products containing arachidonic acid oil contaminated with #cereulide #toxin - Multi-country (#WHO, March 13 '26)

 

Situation at a glance

Multi-country recalls of infant formula and other products have been initiated after cereulide toxin, was detected in batches of multiple internationally distributed brands. 

Investigations have identified arachidonic acid (ARA) oil, used as an ingredient in the implicated products, as the source of contamination. 

However, the full root cause analysis and complete traceability of all affected batches remains under investigation. 

Contaminated formulae, nutritional products, and oil mixes have been distributed to 99 countries and territories across six WHO Regions, with the first product recalls initiated on 10 December 2025. 

Between 1 January and 25 February 2026, 144 suspected and confirmed cases were reported across ten countries in three WHO Regions, with investigations ongoing. 

Based on the available information, WHO assesses the overall public health risk as moderate due to the vulnerability of the affected population (infants), the ongoing uncertainty regarding the full extent of distribution and exposure, and remaining gaps in case detection and root cause information.

Description of the situation

Since 10 December 2025, and as of 25 February 2026, 99 countries and territories have been identified as having received batches of infant formula products subject to recall due to contamination with cereulide toxin. 

During this period, 144 suspected and confirmed cases were reported across 10 countries. The epidemiological investigations and product‑traceback activities remain ongoing in many countries.

The case definitions in use by the International Food Safety Authorities Network (INFOSAN) are currently:

-- Suspect case: 

- A person presenting symptoms of cereulide intoxication with a history of consumption of the recalled product, without laboratory confirmation in a clinical sample.

-- Confirmed case: 

- A person presenting symptoms of cereulide intoxication with a history of consumption of recalled product, with laboratory confirmation in a clinical sample.

Health authorities are actively searching for cases and conducting laboratory testing of human specimens and infant formula products. 

However, case definitions used may differ from those established by INFOSAN, such as those established by the European Centre for Disease Prevention and Control, creating challenges with comparability of reported case numbers.

Since this is not a routinely tested contaminant or condition, diagnostic challenges and limited surveillance capacity are hindering Member States’ ability to identify confirmed cases. One country has laboratory confirmed cases linked to the contaminated products (Belgium).

The limited case numbers appearing in multiple, geographically separated areas is consistent with sporadic exposures to contaminated products that were widely distributed.

​Precautionary recalls have been issued across all countries and territories where products were distributed. 

These measures aim to prevent further exposures, although the speed and completeness of product recall and withdrawal vary by location according to various factors including inspection and enforcement capacities. 

Epidemiology

Cereulide is a heat-stable toxin produced by certain strains of Bacillus cereus, a Gram-positive, spore-forming bacterium ubiquitous in soil, dust, and food production environments. 

The primary hazard in this event is suspected to have occurred during the production of ARA oils used in infant formula, although a root cause analysis has not yet been provided to WHO. 

Cereulide is not contagious; illness occurs only when a person ingests the toxin, such as through consumption of contaminated products. 

The toxin withstands cooking temperatures (stable up to 121°C) and common pasteurization, persisting in finished products. 

Symptoms manifest rapidly, typically within 0.5–6 hours post-ingestion, and usually present as acute gastrointestinal symptoms (nausea, vomiting, abdominal pain) with risk of rapid dehydration and electrolyte imbalance which can be particularly severe in infants due to their physiological vulnerability and limited reserves. 

The toxin has a very low symptomatic dose threshold and remains fully active despite gastric conditions, contributing to its clinical potency. 

For babies who rely entirely on formula, repeated feedings can increase the amount of toxin consumed, and using contaminated formula for rehydration can worsen illness.

The absence of specific antidotes or targeted therapies places greater emphasis on supportive clinical care, effective risk communication to caregivers and health workers, and robust coordination between food safety and public health authorities. 

Where there is limited access to health care and where there may be delays in care seeking, rapid dehydration and electrolyte imbalance in infants may be fatal.

As of 25 February 2026, the following countries have notified suspected cases: 

1) Austria (9), 

2) Brazil (5),  

3) China, Hong Kong SAR, (1), 

4) Czechia (4), 

5) France (11), 

6) Italy (1), 

7) Singapore (3), 

8) Spain (41), and 

9) the United Kingdom of Great Britain and Northern Ireland (61).  

In other countries, including Denmark (32) and the Netherlands (221) the number of suspected cases is based on self-reporting and is therefore not comparable with the INFOSAN case definition.  

To date, Belgium is the only country with laboratory‑confirmed cases, reporting eight confirmed intoxications linked to the implicated products.

Public health response

WHO Response: 

Since 7 January 2026, when distribution of the products was confirmed to extend beyond the European Union, WHO, through the INFOSAN Secretariat, has been contacting INFOSAN Emergency Contact Points in the countries and territories identified as affected to notify them of recalled products exported to their markets and to support information exchange and coordinated response. 

Communication within the European Union has been managed through the European Rapid Alert System for Food and Feed (RASFF), with close coordination between INFOSAN and RASFF.

Response measures in affected countries and territories:

Recalls and communication campaigns have been carried out in many countries and territories where contaminated products were distributed, preventing further exposures despite variable implementation of recall and withdrawal measures. 

Active case-finding and laboratory confirmation efforts are ongoing in affected countries and territories, with most countries and territories reporting no linked illnesses to date.

WHO risk assessment

WHO assesses the overall public health risk associated with this event to be Moderate. 

This assessment is based on the information currently available and reflects the wide international distribution of contaminated products, ongoing uncertainties regarding the full extent of contaminated product distribution, case detection, and root cause of contamination, and the vulnerability of infants and young children to dehydration and electrolyte imbalance from with vomiting illness associated with cereulide toxin ingestion.

Several considerations contribute to this assessment:

-- Cereulide is a thermostable emetic toxin that can cause acute vomiting and rapid dehydration particularly in very young infants which can have severe consequences if untreated; mild or self-limiting cases are likely to go unreported, especially in settings with limited healthcare access or diagnostic capacities.

-- The extent of the contaminated ARA oil distribution remains uncertain, as complete traceability from the original implicated manufacturer has not been provided to WHO. 

-- Secondary distribution through commercial supply chains has further complicated efforts to identify all affected products. Additional investigation is required to determine the source and extent of the cereulide contamination. 

-- The international spread of contaminated products has already disrupted trade and supply chains across at least 99 countries and territories, with the possibility of further recalls if additional affected batches or product categories are identified. These recalls, while essential for public health protection, have created a risk of localized shortage of infant formula, particularly in settings where reliance on specific products is high, despite manufacturers’ efforts to increase production of unaffected products. A residual risk of exposure persists while investigations and traceability efforts continue, as competent authorities manage evolving distribution information and update risk communication measures. 

-- Mild clinical presentations can resemble common childhood illnesses, laboratory capacity for cereulide testing in contaminated products or human samples varies widely, and variations in case definitions across countries complicate consistent reporting and may delay detection. 

-- Although limited numbers of suspected and confirmed cases have been reported to date, without continued investment in surveillance for toxin‑related events, strengthened laboratory networks, training of health‑care providers, and clear communication on recalls and safe alternatives, delays in detection and response could lead to preventable morbidity in infants.

WHO advice

Based on the information available, WHO recommends Member States to maintain epidemiological surveillance, enhance readiness of laboratory capacity for cereulide testing of suspected contaminated products and in clinical samples of suspected cases, and facilitate effective implementation of recalls and withdrawals, as needed.

WHO advises Member States to:  

-- Identify, trace, and withdraw all affected products from the market.

-- Verify the effectiveness of recalls at retail and distribution levels and ensure that affected products are not available for sale, including online sales.

-- Conduct sampling and laboratory testing of suspect products and human specimens.

-- Strengthen requirements for traceability across the supply chain and food recalls.

-- Enhance inspection and oversight of facilities producing or handling ingredients used in infant nutrition.

-- Share relevant information through established international information-sharing mechanisms, including INFOSAN.

-- Issue targeted alerts to consumers, caregivers, health workers, and retailers, while providing clear guidance on identifying and disposing of affected products.

-- Promote breastfeeding and address barriers to accessing safe alternative nutrition.

-- Encourage early presentation to health facilities for infants with sudden vomiting.

-- Reinforce guidance on dehydration management and red-flag symptoms, while supporting availability of tools for safe clinical management of affected infants.

WHO recommends that no restrictions be applied for travel to, or trade with, the countries named in this report, based on the information available on the event reported here.  

Further information

-- European Centre for Disease Prevention and Control (ECDC) and European Food Safety Authority (EFSA). Multi-country foodborne event caused by cereulide in infant formula products. 19 February 2026. Available from: https://www.ecdc.europa.eu/en/publications-data/multi-country-foodborne-event-caused-cereulide-infant-formula-products  

-- European Food Safety Authority (EFSA). EFSA provides rapid risk assessment on cereulide in infant formula. EFSA; 1 February 2026. https://www.efsa.europa.eu/en/news/efsa-provides-rapid-risk-assessment-cereulide-infant-formula

-- European Centre for Disease Prevention and Control (ECDC). Communicable disease threats report, 31 January–6 February 2026 (Week 6). ECDC; 12 February 2026. https://www.ecdc.europa.eu/sites/default/files/documents/Communicable-disease-threats-report-week-6-2026.pdf  

-- European Food Safety Authority (EFSA). Precautionary global recall of infant nutrition products following detection of Bacillus cereus. EFSA; 27 January 2026. https://www.efsa.europa.eu/en/news/precautionary-global-recall-infant-nutrition-products-following-detection-bacillus-cereus  

-- European Centre for Disease Prevention and Control (ECDC). Precautionary global recall of infant nutrition products following detection of Bacillus cereus. ECDC; 27 January 2026.  https://www.ecdc.europa.eu/en/news-events/precautionary-global-recall-infant-nutrition-products-following-detection-bacillus  

-- European Centre for Disease Prevention and Control. European outbreak case definition: cereulide contamination of infant formula products (EpiPulse event 2025-FWD-00107). Stockholm: ECDC; 2026. https://www.ecdc.europa.eu/sites/default/files/documents/Case%20definition%20cereulide%20event.pdf

-- World Health Organization. Strengthening surveillance of and response to foodborne diseases. WHO; 11 December 2025. https://www.who.int/publications/i/item/9789240118188  

-- Austrian Agency for Health and Food Safety (AGES). Update: Information on cereulide in infant formula. AGES; 1 February 2026. https://www.ages.at/en/news/detail/update-information-zu-cereulid-in-saeuglingsnahrung  

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Citable reference: World Health Organization (13 March 2026). Disease Outbreak News;  Recall of internationally distributed infant formula and products containing ARA oil due to contamination with cereulide toxin. Available at: https://www.who.int/emergencies/disease-outbreak-news/item/2026-DON596 

Source: 

Link: https://www.who.int/emergencies/disease-outbreak-news/item/2026-DON596

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Rapid #Risk #Assessment, Acute Event of Potential Public Health Concern: #Nipah Virus #Infection - Global (#WHO, Mar. 6 '26, summary)

 

{Summary}

Risk Statement  

-- This Rapid Risk Assessment (RRA) evaluates the global public health risk posed by Nipah virus (NiV), considering the distinct epidemiological profiles of 

- i) enzootic countries, where recurrent zoonotic spillover and limited human‑to‑human transmission continue to occur, and 

- ii) non‑enzootic regions, where the risk remains primarily associated with infected travellers or importation of infected livestock. 

-- The assessment considers the ecological and seasonal drivers of spillover, the constrained efficiency of human‑to‑human transmission, and the capacity of health and community systems to detect, confirm, and rapidly contain outbreaks. 

-- Given that NiV has not demonstrated sustained transmission beyond outbreak settings and no human cases have ever been reported outside Asia, the global risk is largely determined by localized outbreaks in endemic areas and the very low likelihood of onward transmission following importation. 

-- NiV activity remains geographically limited, with human cases occurring primarily in the South-East Asia Region with limited outbreaks in the Western Pacific Region. 

-- The epidemiological profile of NiV is characterized by low frequency, localized outbreaks, occurring predominantly in Bangladesh and India, with additional historical events reported in Malaysia, Singapore, and the Philippines. 

-- Bangladesh has reported sporadic cases almost annually since 2001, largely associated with consumption of raw date palm sap, following a well‑defined seasonal pattern between December and April. 

-- India reported its first outbreak in 2001 and has documented near-annual cases in Kerala since 2018 with sporadic cases reported in West Bengal. 

-- In 2025, eight laboratory‑confirmed cases were detected across Bangladesh (four) and India (four). 

-- As of March 2026, three sporadic cases have been reported in the two countries, two in India and one in Bangladesh. 

-- Malaysia (1998–1999), Singapore (1999), and the Philippines (2014) experienced outbreaks previously but have not reported any additional NiV events recently. 

-- Although NiV has a high case‑fatality ratio (40–75%), transmission remains limited in scale, typically arising from isolated spillover events linked to fruit bats, contaminated fruits or fruit products, or occasionally infected livestock. 

-- Human‑to‑human transmission has been documented, particularly in Bangladesh and India. However, sustained community transmission or multi‑country spread has never been observed. 

KEY RISK FACTORS 

{1.} Risk to Enzootic Countries  

• Sporadic zoonotic spillover events occur due to contact with infected bats or consumption of contaminated fruits or fruit products.  

• Serological evidence of NiV circulation beyond affected areas in Bangladesh and India (Kerala and West Bengal), suggest that spillover could potentially occur in other areas where infected bats are present. 

• Human‑to‑human transmission, although documented, is limited to close contacts and has not resulted in widespread community transmission. 

• The case‑fatality ratio is high; however, the total number of reported cases remains low. 

• Health care settings may amplify transmission when infection prevention and control (IPC) measures are insufficient.  

• Spillover from other susceptible animal hosts (pigs, horses) cannot be ruled out, nor the risk of importation through infected livestock, though probably very low.  

{2.} Risk to Non‑Enzootic Regions (reservoirs may be present; no human cases to date) 

• Risk is primarily associated with an infected traveller. 

• No human NiV transmission has ever been reported outside affected Asian countries. 

• In settings without established animal reservoirs or intermediate hosts, onward transmission following importation is unlikely and would require close, prolonged contact. 

• Historical spread via movement of infected animals (e.g., pigs exported from Malaysia to Singapore in 1999) demonstrates that animal trade–related spillover is possible, however current evidence suggests that the risk under present animal‑health and trade practices is likely very low.  

{3.} Risk to Countries Without Known Bat Reservoirs (reservoirs absent; no human cases) 

• Importation via travellers (and, exceptionally, livestock) may occur and while secondary transmission is possible it is unlikely, given the absence of established animal reservoirs and the need for close contact for human‑to‑human spread. 

{4.} Risk to Travellers 

• Travellers to affected areas face a very low but non‑zero risk, particularly if they have direct exposure to fruit bats, consume contaminated food products, or come into contact with other infected animals, including pigs or horses. 

• Returning infected travellers pose a limited risk of onward transmission due to low NiV transmissibility. 

{5.} Risk Determinants 

• Ecological presence of Pteropodidae bats in enzootic countries.  

• Presence of potential intermediary hosts that could transmit to humans (e.g., pigs, horses).  

• Cultural and dietary practices (e.g., consumption of raw date palm sap). 

• Exposure in health care settings with inadequate IPC measures. 

• Limited awareness among communities and health workers. 

• Close, unprotected contact with sick/deceased individuals, including local practice traditions. 

{6.} Response Capacity 

• Countries with recurring outbreaks have strengthened their surveillance systems, diagnostics, and clinical management capacity. 

• No licensed vaccines or specific antiviral treatments are currently available; however, several vaccine and therapeutics candidates are in development, supported by CEPI and WHO‑aligned research priorities.  

• Rapid case isolation and contact tracing remain effective measures in preventing wider spread. 

{7.} Confidence in Available Information 

-- Overall confidence is moderate, due to: 

• Under‑detection of sporadic spillover events in rural areas. 

• Ongoing uncertainty about the full geographic distribution of bat reservoirs and potential intermediate hosts.  

-- Based on current evidence, characterized by rare outbreaks, limited human‑to‑human transmission, no sustained global spread, and improving response capacity, the overall global public health risk posed by NiV is assessed as Low with a Moderate level of confidence in the available information.  

-- This rapid risk assessment will be updated as new epidemiological, clinical, or virological information becomes available. 

(...)

Source: 

Link: https://www.who.int/publications/m/item/who-rapid-risk-assessment---nipah-virus---global---version-1

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#Report of the 49th meeting of #WHO Global Advisory #Committee on #Vaccine #Safety 27–28 November 2025 (Excerpt, Mar. 6 '26)

 

{Excerpt}

(...)

COVID-19 current vaccine safety status and insights 

-- Since 2021, GACVS has regularly reviewed the safety of COVID-19 vaccines, including through global pharmacovigilance data and dedicated reviews of myocarditis, pregnancy outcomes and other adverse events of special interest (AESI). 

-- The most recent updates reaffirmed that the benefits of vaccination outweigh the risks across all groups and advised continued monitoring for younger males and follow-up of persons who have reported vaccine-associated myocarditis. 

-- Many individuals have received three or more doses of COVID-19 vaccine. 

-- Some adverse events – such as myocarditis – seem to occur mainly after the second dose of mRNA COVID- 19 vaccines. 

-- However, the outcomes were less severe in persons who developed myocarditis after vaccination compared to those unvaccinated and following infections, including SARS- CoV-2. 

-- Also, children under six months of age seem to be at higher risk of severe COVID-19 infection along with people over the age of 65 years. 

-- WHO has recommended continued vaccination for high-priority groups while acknowledging that gaps remain in the evidence on the safety of repeated dosing, long-term outcomes, and in subgroups such as children and pregnant women. 

-- As of October 2025, for all COVID-19 vaccines, there were only 32 cases of perturbation of fetal development in EudraVigilance, of which most were reported with the original vaccine strains. 

-- An analysis of safety of protein-based COVID-19 vaccines by the Uppsala Monitoring Centre (UMC) showed that as of November 2025 there were almost 6 million reports for all COVID-19 vaccines in UMC’s VigiBase. 

-- Of these, 16 548 reports concerned updated COVID-19 vaccine variants; among these were 5085 reports for updated protein-subunit vaccines. 

-- Around 17.4% of these were serious, and 50 reported a fatal outcome. 

-- Most reports were for the variant NVX CoV 2373 and most deaths were older vaccinees aged 75 years or more. 

-- GACVS reviewed findings from the Scandinavian collaboration called SCOPE (Scandinavian studies of COvid-19 in PrEgnancy). 

-- Findings showed no increased risk of adverse pregnancy, maternal or neonatal outcomes after mRNA COVID-19 vaccination in pregnancy in Denmark, Norway and Sweden. 

-- As of September 2025, the recommendation for vaccination in pregnancy was revised to apply only to specific high-risk groups. 

-- A case-control study by SCOPE of all women with a miscarriage before 14 weeks and all women with a primary care-based confirmation of an ongoing pregnancy in the first trimester revealed no evidence of increased risk of early pregnancy loss after COVID-19 vaccination. 

-- A further investigation of COVID-19 infection and vaccination with mRNA vaccines during the first trimester of pregnancy and the risk of congenital anomalies, in a population-based cohort of 150 000 live-born infants in Denmark, Norway and Sweden, showed no increased risk of major congenital anomalies among infants whose mothers were vaccinated against COVID-19 during the first trimester. 

-- A SCOPE investigation of the association between COVID-19 vaccination and several pregnancy outcomes among a cohort of almost 160 000 singleton pregnancies between January 2021 and 2022 in Norway and Sweden showed that vaccination against COVID-19 during pregnancy was not associated with any of the studied adverse pregnancy outcomes. 

-- In another SCOPE study of COVID-19 vaccination during pregnancy and the risk of severe postpartum haemorrhage, including more than 300 000 single-term deliveries in Denmark, Norway and Sweden, no evidence was found of an association between COVID-19 vaccination at any time during pregnancy and severe postpartum hemorrhage. 

-- Finally, SCOPE investigated neonatal outcomes after COVID-19 vaccination with mRNA vaccine during pregnancy in a cohort of almost 200 000 infants in Norway and Sweden. 

-- Again, no increased odds were found of any adverse neonatal outcomes and neonatal mortality. 

-- In consideration of the evidence presented, GACVS members agreed the following: 

- Repeated-dose safety (including boosters with variant-containing vaccines): 

* Current evidence remains reassuring, with no new safety signals recently identified. 

- Safety of protein-based vaccines: 

* While generally well tolerated, reported adverse events include a proportion of serious individual case safety reports (ICSRs) in the global database. Several potential signals (e.g. tinnitus, antibody-dependent enhancement, thrombosis) require further evaluation. Additional data collection and analysis are therefore recommended to strengthen the evidence base for these vaccines. 

- Long-term outcomes of known risks (e.g. myocarditis, pregnancy outcomes): 

* Myocarditis continues to occur predominantly in younger adults, typically with mild-to- moderate severity and most frequently after the second dose. Longer follow-up studies are needed to define the long-term prognosis and risks of revaccination in affected individuals. 

- Subgroup-specific safety (children, young males, older adults, immunocompromised individuals, pregnant women): 

* Evidence to date shows no harmful effects of mRNA COVID-19 vaccination during pregnancy, including no increase in congenital anomalies, adverse perinatal outcomes, or some post-natal complications. Some studies even suggest lower odds of intracranial haemorrhage, cerebral ischaemia and neonatal mortality among infants of vaccinated mothers. 

- Safety monitoring during the transition to endemic COVID-19 vaccination: 

* Continued vigilance is required, particularly regarding more recent variant-adapted vaccines which remain safe on the basis of current data. Enhanced monitoring of protein-based vaccines is important given the comparatively limited evidence and the presence of identified risks that warrant further investigation.

(...)

Source: 

Link: https://www.who.int/publications/journals/weekly-epidemiological-record

____

#Statement of the 44th #Meeting of the #Polio #IHR #Emergency Committee (#WHO, summary)

 

{4 March 2026, excerpts}

The 44th meeting of the Emergency Committee under the International Health Regulations (IHR or Regulations) on the international spread of poliovirus was convened by the WHO Director-General on 14 January 2026 with eight out of nine Committee members and the adviser meeting via video conference with affected countries, supported by the WHO Secretariat. 

The Emergency Committee reviewed the latest epidemiological data on wild poliovirus type 1 (WPV1) and circulating vaccine-derived polioviruses (cVDPV) in the context of the global targets to interrupt endemic WPV1 transmission in 2026 and to stop cVDPV2 outbreaks by 2028 with subsequent certification of WPV1 eradication and cVDPV2 elimination. 

Technical updates were received about the situation in the following countries: 

- Afghanistan, 

- Angola, 

- Germany, 

- Lao People’s Democratic Republic, 

- Namibia, 

- Pakistan and 

- Papua New Guinea.

Amendments to the IHR, adopted by the Seventy-seventh World Health Assembly, through resolution WHA77.17 in June 2024, entered into force, generally, on 19 September 2025.

Key amendments to the IHR include, inter alia, broader poliovirus notification requirements; the introduction of the determination of “pandemic emergency” , a higher level of global public health alert with respect to a public health emergency of international concern (PHEIC); measures to strengthen equitable access to relevant health products; and recognition of health documents in non-digital and digital formats.

(...)

Conclusion

The Committee unanimously concluded that the risk of international spread of polioviruses continues to constitute a Public Health Emergency of International Concern (PHEIC) and recommended extending the Temporary Recommendations for a further three months.

The Committee, after a thorough review of the epidemiological and programmatic situation, unanimously concluded that the event does not constitute a pandemic emergency.

(...)

Source: 

Link: https://www.who.int/news/item/04-03-2026-statement-of-the-forty-fourth-meeting-of-the-polio-ihr-emergency-committee

____

Recommended #composition of #influenza virus #vaccines for use in the 2026 – 2027 northern hemisphere influenza season (#WHO, Feb. 27 '26)

 

February 2026 

WHO convenes technical consultations {1} in February and September each year to recommend viruses for inclusion in influenza vaccines {2} for the northern hemisphere (NH) and southern hemisphere (SH) influenza seasons, respectively. 

This recommendation relates to the influenza vaccines for use in the NH 2026-2027 influenza season. 

A recommendation will be made in September 2026 relating to vaccines that will be used for the SH 2027 influenza season. 

WHO guidance for choosing between the NH and SH formulations for countries in tropical and subtropical regions is available on the WHO Global Influenza Programme website {3}.  

National or regional authorities approve the composition and formulation of influenza vaccines used in each country. 

National public health authorities are responsible for making recommendations regarding the use of the vaccine. 

WHO has published recommendations on the prevention of influenza {4}.  

Seasonal influenza activity 

From September 2025 through January 2026, influenza activity was reported in all transmission zones. 

Overall influenza virus detections were higher compared to the same reporting period in 2024-2025 but peaked in December 2025 for this recent period compared to February 2025 for the previous period. 

During this reporting period, influenza A viruses predominated, although the proportion of virus detections varied among transmission zones. 

In Africa, influenza activity increased during the start of the reporting period, with a predominance of influenza A viruses in all transmission zones. 

In Eastern, Northern, and Western Africa, among subtyped influenza A viruses, A(H1N1)pdm09 viruses accounted for the majority of detections early in the reporting period while A(H3N2) viruses predominated later in the reporting period. 

Influenza detections peaked in November in Western Africa and December in Eastern and Northern Africa. 

In Middle Africa, influenza detections remained low throughout the reporting period with a slight predominance of A(H1N1)pdm09 viruses early in the reporting period. 

In Southern Africa, influenza detections remained low throughout the reporting period, with a predominance of influenza A viruses. 

In Northern and Middle Africa, there was low and sustained influenza B activity throughout the reporting period. 

In Asia, influenza activity increased during the start of the reporting period in South East and Western Asia, from October in Central and Eastern Asia, and from November in Southern Asia, with a predominance of influenza A viruses in all transmission zones. 

Most influenza detections were reported from Eastern Asia, where activity peaked in early December. 

In Southern Asia, influenza activity also peaked in December; in Central Asia influenza activity peaked in November, and in Western and South East Asia, influenza activity peaked in October. 

Among subtyped influenza A viruses, A(H3N2) viruses accounted for the majority of detections in all transmission zones; detections of A(H1N1)pdm09 and influenza B viruses remained low in most transmission zones throughout the reporting period, except in Eastern Asia where there was a substantial rise in influenza B viruses in recent weeks. 

In Europe, influenza activity increased from mid-September in Northern Europe, from October in South West Europe and from mid-November in Eastern Europe, with a predominance of influenza A viruses in all transmission zones. 

Influenza detections peaked in December in Northern and South West Europe but remained elevated through January. 

Influenza detections continued to increase through January in Eastern Europe. 

Among subtyped influenza A viruses, A(H3N2) viruses predominated. 

In South West Europe, detections of A(H1N1)pdm09 viruses slightly increased in mid-November. 

In Eastern and Northern Europe, detections of A(H1N1)pdm09 and influenza B viruses remained low throughout the reporting period.  

In the Americas, influenza activity increased from the start of the reporting period in Temperate and Tropical South America and from November in North America and Central America Caribbean. 

Influenza A viruses accounted for most detections, and influenza B virus detections remained low throughout the reporting period in all transmission zones, except in North America where there was a substantial rise in influenza B viruses in recent weeks. 

In North America, activity peaked in late December. 

Among subtyped influenza A viruses, there was a predominance of A(H3N2) viruses. 

In Central America Caribbean, influenza activity remained elevated through mid-January with A(H3N2) virus detections predominant from December. 

In Tropical South America, influenza activity peaked in early November and slowly declined until the end of the reporting period. 

Among subtyped influenza A viruses, A(H3N2) predominated through November then co-circulated at similar proportions to A(H1N1)pdm09 until the end of the reporting period. 

In Temperate South America, influenza activity peaked in mid-November and among subtyped influenza A viruses, A(H3N2) viruses predominated throughout the reporting period.  

In Oceania, influenza activity decreased until mid-October, increased in December and decreased since mid-December. A(H1N1)pdm09 and B viruses were detected at similar levels until mid-September and A(H3N2) virus detections predominated since then. 

Influenza A 

Globally, influenza A virus detections greatly outnumbered those of influenza B. 

Among subtyped influenza A viruses, A(H3N2) viruses predominated throughout the reporting period in most transmission zones. 

In Eastern, Northern, Western Africa, Central America Caribbean and Oceania, influenza A(H1N1)pdm09 virus detections predominated during the first part of the reporting period, and A(H3N2) virus detections predominated in the latter part of the reporting period. 

Influenza A(H1N1)pdm09 virus detections increased slightly towards the latter part of the reporting period in Eastern and South West Europe, Central America Caribbean and Tropical South America. 

The overall number of influenza detections was low in Middle and Southern Africa. 

Influenza B 

Globally, influenza B virus detections remained low throughout the reporting period. 

Increases in influenza B virus detections in January were reported in North America and Eastern Asia. 

All influenza B viruses where lineage was confirmed belonged to the B/Victoria lineage. 

(...)

Zoonotic influenza  

From 23 September 2025, sporadic zoonotic influenza infections were reported, in most cases, following exposure to infected birds, swine or contaminated environments. 

Single cases of A(H5N1) from Bangladesh, A(H5N2) from Mexico, and A(H5N5) from the United States of America were reported. 

Three A(H5N1) cases were reported from Cambodia. 

Fourteen cases of A(H9N2) and one case of A(H10N3) were reported from China. 

Single cases of A(H1N1)v and A(H1N2)v were reported from China, a case of A(H1N2)v from the United States of America, and a case of A(H3N2)v from Brazil. 

Genetic and antigenic characteristics of recent seasonal influenza viruses, human serology and antiviral susceptibility 

Influenza A(H1N1)pdm09 viruses  

Since September 2025, A(H1N1)pdm09 viruses circulated globally, but did not predominate in any region. 

The haemagglutinin (HA) genes of viruses that were genetically characterized belonged to the 5a.2a and 5a.2a.1 clades. 

Viruses from clade 5a.2a subclades C.1, C.1.9 and C.1.9.3 circulated in low numbers, with the largest proportion of detections in Africa {5}. 

Since September 2025, clade 5a.2a.1 subclades D.3.1 and D.3.1.1 viruses circulated globally. 

The D.3.1 subclade with substitutions T120A, I372V, I460T and V520A predominated in Western Pacific, Africa, South East Asia and several countries in the Americas. 

D.3.1.1 viruses characterized by R113K and more recently acquired substitutions A139D, E283K and K302E predominated in some countries in Europe, the Middle East and North America. 

The antigenic properties of A(H1N1)pdm09 viruses were assessed in haemagglutination inhibition (HI) assays with post-infection ferret antisera. 

HI results for viruses with collection dates since September 2025 showed that ferret antisera raised against cell culture-propagated A/Wisconsin/67/2022-like and eggpropagated A/Victoria/4897/2022-like viruses from the 5a.2a.1 clade recognized viruses in both 5a.2a and 5a.2a.1 clades well. 

However, post-infection ferret antisera raised against viruses from clade 5a.2a showed some reduction in recognition of the now predominating D.3.1 and D.3.1.1 subclade viruses. 

Post-infection ferret antisera raised against viruses from subclade D.3.1 (e.g., A/Missouri/11/2025) recognized recently circulating viruses from both 5a.2a and 5a.2a.1 clades well.  

Human serology studies used 15 serum panels from children, adults (18 to 64 years) and older adults (≥65 years) who had received egg-propagated inactivated (standard, high dose or adjuvanted), cell culture-propagated inactivated or recombinant trivalent or quadrivalent vaccines with NH 2025-2026 influenza vaccine formulations. 

-- NH 2025-2026 egg-based vaccines contained A/Victoria/4897/2022 (H1N1)pdm09like, 

-- A/Croatia/10136RV/2023 (H3N2)-like, 

-- B/Austria/1359417/2021-like (B/Victoria lineage) and, in quadrivalent vaccines, 

-- B/Phuket/3073/2013-like (B/Yamagata lineage) virus antigens. 

Cell culture-propagated and recombinant vaccines contained A/Wisconsin/67/2022 (H1N1)pdm09-like, A/District of Columbia/27/2023 (H3N2)-like and B/Austria/1359417/2021-like (B/Victoria lineage) virus antigens. 

Recent A(H1N1)pdm09 viruses with HA genes from clades 5a.2a (subclade C.1.9.3) and 5a.2a.1 (subclades D.3.1 and D.3.1.1) were analysed in HI assays using these human serum panels. 

When compared to the responses to cell culture-propagated A/Wisconsin/67/2022 (H1N1)pdm09-like vaccine reference viruses, post-vaccination geometric mean titres (GMTs) were significantly reduced for some recently circulating viruses from D.3.1 and D.3.1.1 subclades. 

Of 1 161 A(H1N1)pdm09 virus clinical samples and isolates examined by genetic and/or phenotypic analyses, 15 viruses showed evidence of reduced susceptibility to neuraminidase inhibitors (NAIs): seven had an H275Y neuraminidase (NA) substitution and eight had I223V and S247N substitutions. 

Of 1 331 A(H1N1)pdm09 viruses examined by genetic and/or phenotypic analyses, no viruses showed evidence of reduced susceptibility to the endonuclease inhibitor baloxavir marboxil. 

Influenza A(H3N2) viruses  

Phylogenetic analysis of the HA gene sequences of A(H3N2) viruses collected since September 2025 showed that the vast majority of viruses belonged to one of the J.2 subclades {6}, expressing HA N122D and K276E substitutions. 

HA genes have diversified with many subclades; J.2.2 (characterized by S124N), J.2.3 (characterized by N158K, K189R and S378N), J.2.4 (characterized by T135K [a potential loss of an N-glycosylation site] and K189R), and K (formerly designated as J.2.4.1; characterized by K2N, S144N [a potential addition of an N-glycosylation site], N158D, I160K, Q173R, T328A and S378N). 

During this reporting period, subclade K viruses were detected in all regions and predominated in many countries. 

There was still circulation of other J.2 subclades, notably J.2 or J.2.3 in South America, J.2.2 or J.2.4 in Africa and Asia.  

Post-infection ferret antisera raised against cell culture-propagated A/District of Columbia/27/2023-like and egg-propagated A/Croatia/10136RV/2023-like (clade 2a.3a.1, subclade J.2) viruses, representing the A(H3N2) component for the NH 2025-2026 influenza vaccines, showed poor recognition with recently circulating subclade J.2.3 (e.g., A/Netherlands/10685/2024), J.2.4 (e.g., A/Sydney/1359/2024) and K (e.g., A/Darwin/1415/2025) viruses. 

Ferret antisera raised against reference viruses from J.2.3 subclades showed good recognition of viruses expressing HA from J.2.3, but poor recognition of other subclades.  

Post-infection ferret antisera raised against cell culture-propagated A/Sydney/1359/2024-like and eggpropagated A/Singapore/GP20238/2024-like J.2.4 viruses, representing SH 2026 influenza vaccines, recognized most J.2.4 viruses and many subclade K viruses well. 

However, subclade K viruses and J.2.4 viruses with HA substitutions F79V, S144N (addition of a potential N-glycosylation site), N158D, I160K, T328A were better recognized by post-infection ferret antisera raised against cell culture-propagated A/Darwin/1415/2025-like and egg-propagated A/Darwin/1454/2025-like (subclade K) viruses. 

Human serology studies were conducted using the serum panels as described above by HI and virus neutralization (VN) assays with recent circulating A(H3N2) viruses with HA genes from subclades J.2, J.2.2, J.2.3, J.2.4, J.2.5 and K. 

When compared to titres against cell-propagated A/District of Columbia/27/2023-like vaccine reference viruses, post-vaccination HI GMTs or VN GMTs against many of the recent viruses in all subclades tested were significantly reduced in many serum panels.  

(...)

Of 4 458 influenza A(H3N2) viruses examined by genetic and/or phenotypic analyses, two viruses showed evidence of reduced susceptibility to NAIs; both had an NA E119V substitution. 

Of 4 828 A(H3N2) viruses examined by genetic and/or phenotypic analyses, nine viruses showed evidence of reduced susceptibility to the endonuclease inhibitor baloxavir marboxil: three had a PA I38T substitution, three had a PA I38I/T substitution, two had a PA I38I/M substitution and one had a PA E199E/G substitution.  

Influenza B viruses  

Since September 2025, influenza B viruses were detected in all WHO regions, and all those characterized belonged to the B/Victoria lineage. 

There have been no confirmed detections of circulating B/Yamagata lineage viruses after March 2020.  

All HA genes of B/Victoria lineage viruses characterized during this reporting period belonged to clade 3a.2 with HA substitutions A127T, P144L, and K203R. 

Viruses with clade 3a.2 HA genes have diversified further, forming several subclades (C.1-C.5)7. 

Viruses designated as C.5, C.5.1, C.5.6, C.5.6.1 and C.5.7, all of which had the HA substitution D197E, circulated at varying proportions in different regions. 

Viruses designated as C.3 have HA substitutions E128K, A154E and S208P. 

Subclade C.3.1 viruses shared additional mutations D197N (addition of a potential N-glycosylation site) and P208S. 

Recent C.3 viruses which had additional changes D197N (addition of a potential N-glycosylation site), S255P and I267V and C.3.1 viruses have been detected in increasing proportions in Eastern Asia and North America in recent weeks. 

Antigenic analysis showed that post-infection ferret antisera raised against B/Austria/1359417/2021-like viruses (3a.2), representing the vaccine viruses for the SH 2026 and NH 2025-2026 influenza seasons, recognized viruses within the C.5.1, C.5.6, C.5.6.1 and C.5.7 subclades well. 

C.3 and C.3.1 subclade viruses with the HA substitution D197N were recognized poorly. 

Post-infection ferret antisera raised against cell culture-propagated viruses from subclade C.3.1 (e.g., B/Pennsylvania/14/2025) recognized recently circulating viruses from C.3, C.3.1 and other 3a.2 subclades well. 

All available egg isolates for subclade C.3 and C.3.1 viruses acquired substitutions that remove the potential N-glycosylation site at HA 197 to 199. 

Post-infection ferret antisera raised against egg-propagated viruses from subclade C.3.1 (e.g., B/Tokyo/EIS13-175/2025, B/Tokyo/EIS13-011/2025, B/Perth/115/2025) showed reduced recognition of recently circulating viruses from C.3 and C.3.1 subclades compared to that of the cell equivalent.  

(...)

In human serology studies, recently circulating B/Victoria lineage viruses with HA genes from clade 3a.2 subclades C.3, C.3.1, C.5.1, C.5.6, C.5.6.1 and C.5.7 were tested using the serum panels described above. 

When compared to titres against egg- or cell culture-propagated B/Austria/1359417/2021-like vaccine reference virus, titres against most viruses with HA genes from C.5.1, C.5.6, C.5.6.1 and C.5.7 subclades were not significantly reduced; however, titres against viruses with HA genes from C.3 and C.3.1 were significantly reduced in most serum panels. Serology studies were not performed for B/Yamagata lineage viruses.  

Of 549 influenza B/Victoria lineage viruses examined by genetic and/or phenotypic analyses, two showed evidence of reduced or highly reduced susceptibility to NAIs, both with an NA M464T substitution. 

Of 760 B/Victoria lineage viruses examined by genetic and/or phenotypic analyses, no viruses showed evidence of reduced susceptibility to the endonuclease inhibitor baloxavir marboxil.  

Recommended composition of influenza virus vaccines for use in the 2026-2027 northern hemisphere influenza season  

Since September 2025, A(H1N1)pdm09 viruses circulated globally. The majority of viruses had HA genes belonging to the 5a.2a.1 clade which has further diversified into the D.3.1 and D.3.1.1 subclades. 

Postinfection ferret antisera raised against the northern hemisphere (NH) 2025-2026 A(H1N1)pdm09 vaccine viruses (cell culture-propagated A/Wisconsin/67/2022 and egg-propagated A/Victoria/4897/2022) and the southern hemisphere (SH) 2026 A(H1N1)pdm09 vaccine viruses A/Missouri/11/2025 recognized D.3.1 and D.3.1.1 viruses well. 

In human serology studies, post-vaccination geometric mean titres (GMTs) were significantly reduced for some recently circulating A(H1N1)pdm09 viruses when compared to the responses to cell culture-propagated A/Wisconsin/67/2022 A(H1N1)pdm09-like vaccine reference viruses. 

Since September 2025, A(H3N2) viruses circulated and predominated globally. 

The vast majority of A(H3N2) viruses collected had HA genes from subclades of J.2 and have continued to diversify with subclade K (previously designated as J.2.4.1) viruses predominating in most regions. 

Post-infection ferret antisera raised against NH 2025-2026 influenza season vaccine viruses (cell culture-propagated A/District of Columbia/27/2023 and egg-propagated A/Croatia/10136RV/2023) recognized some J.2 viruses well but showed poor recognition of viruses from subclades J.2.3, J.2.4 and K. 

Post-infection ferret antisera raised against subclade K viruses (cell culture-propagated A/Darwin/1415/2025 and egg-propagated A/Darwin/1454/2025) showed improved recognition of K viruses compared to post-infection antisera raised against NH 2025-2026 and SH 2026 A(H3N2) vaccine viruses. 

When compared to titres against cell culture-propagated A/District of Columbia/27/2023-like vaccine reference viruses, human post-vaccination haemagglutinin inhibition (HI) GMTs or virus neutralisation (VN) GMTs against many of the recent viruses in J.2.3, J.2.4 and K subclades were significantly reduced. 

Since September 2025, influenza B virus detections remained low globally, although some countries had increased detections in recent weeks. All circulating influenza B viruses characterized belonged to the B/Victoria lineage, and had HA genes belonging to clade 3a.2 with substitutions A127T, P144L and K203R. 

Post-infection ferret antisera raised against B/Austria/1359417/2021-like viruses (3a.2), representing the vaccine viruses for the SH 2026 and NH 2025-2026 influenza seasons, recognized viruses within the C.5.1, C.5.6, C.5.6.1 and C.5.7 subclades well. C.3 and C.3.1 subclade viruses with HA substitution D197N were recognized poorly. 

Post-infection ferret antisera raised against cell culture-propagated viruses from subclade C.3.1 (e.g., B/Pennsylvania/14/2025) recognized recently circulating viruses from C.3, C.3.1 and other 3a.2 subclades well. All available egg isolates for subclade C.3 and C.3.1 viruses (e.g., B/Tokyo/EIS13-175/2025) acquired egg-adaptive mutations that remove the potential N-glycosylation site at HA 197 to 199, leading to post-infection ferret antisera raised against egg-propagated viruses from subclade C.3.1 (e.g., B/Tokyo/EIS13-175/2025) showing reduced recognition of recently circulating viruses from C.3 and C.3.1 subclades compared to that of the cell equivalent. 

Human serology assays showed that post-vaccination titres against most recent B/Victoria lineage viruses with HA genes from subclades C.5.1, C.5.6, C.5.6.1 and C.5.7 were not significantly reduced when compared to titres against egg- or cell culturepropagated B/Austria/1359417/2021-like vaccine reference viruses. Titres against viruses with HA genes from subclade C.3 and C.3.1 were significantly reduced in most serum panels.  

For vaccines for use in the 2026-2027 northern hemisphere influenza season, WHO recommends the following:  

Egg-based vaccines  

• an A/Missouri/11/2025 (H1N1)pdm09-like virus;  

• an A/Darwin/1454/2025 (H3N2)-like virus; and  

• a B/Tokyo/EIS13-175/2025 (B/Victoria lineage)-like virus.  

Cell culture-, recombinant protein- or nucleic acid-based vaccines  

• an A/Missouri/11/2025 (H1N1)pdm09-like virus;  

• an A/Darwin/1415/2025 (H3N2)-like virus; and  

• a B/Pennsylvania/14/2025 (B/Victoria lineage)-like virus.  

Lists of prototype viruses for egg-, cell culture-, recombinant protein- and nucleic acid-based vaccines together with candidate vaccine viruses (CVVs) suitable for the development and production of human influenza vaccines are available on the WHO website {8}. 

A list of reagents for vaccine standardization, including those for this recommendation, can also be found on the WHO website.  

CVVs and reagents for use in the laboratory standardization of inactivated vaccines may be obtained from:  

• Therapeutic Goods Administration, P.O. Box 100, Woden, ACT, 2606, Australia (email: influenza.reagents@health.gov.au; website: http://www.tga.gov.au).  

• Medicines and Healthcare products Regulatory Agency (MHRA), Blanche Lane, South Mimms, Potters Bar, Hertfordshire, EN6 3QG, the United Kingdom of Great Britain and Northern Ireland  • (email: enquiries@mhra.gov.uk; website: http://www.nibsc.org/science_and_research/virology/influenza_resource_.aspx). 

• Division of Biological Standards and Quality Control, Center for Biologics Evaluation and Research, Food and Drug Administration, 10903 New Hampshire Avenue, Silver Spring, Maryland, 20993, the United States of America (email: cbershippingrequests@fda.hhs.gov).  

• Research Centre for Influenza and Respiratory Viruses, National Institute of Infectious Diseases, 4-7-1 Gakuen, Musashi-Murayama, Tokyo 208-0011, Japan (email: flu-vaccine@nih.go.jp).  

Requests for reference viruses should be addressed to:  

• WHO Collaborating Centre for Reference and Research on Influenza, VIDRL, Peter Doherty Institute, 792 Elizabeth Street, Melbourne, Victoria 3000, Australia (email: whoflu@influenzacentre.org; website: http://www.influenzacentre.org).  

• WHO Collaborating Centre for Reference and Research on Influenza, National Institute of Infectious Diseases, Japan Institute for Health Security 4-7-1 Gakuen, Musashi-Murayama, Tokyo 208-0011, Japan (email: whocc-flu@nih.go.jp).  

• Influenza Division, Centers for Disease Control and Prevention, 1600 Clifton Road, Mail Stop H17-5, Atlanta, GA 30329, the United States of America (email: InfluenzaVirusSurvei@cdc.gov; website: http://www.cdc.gov/flu/).  

- WHO Collaborating Centre for Reference and Research on Influenza, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, the United Kingdom of Great Britain and Northern Ireland (Tel: +44 203 796 1520 or +44 203 796 2444, email: whocc@crick.ac.uk;  • website: http://www.crick.ac.uk/research/worldwideinfluenza-centre).  

• WHO Collaborating Centre for Reference and Research on Influenza, National Institute for Viral Disease Control and Prevention, China CDC, 155 Changbai Road, Changping District, 102206, Beijing, China. (tel: +86 10 5890 0851; email: fluchina@ivdc.chinacdc.cn; website: https://ivdc.chinacdc.cn/cnic/en/).  

WHO provides weekly updates {9} of global influenza activity. Other information about influenza surveillance, risk assessment, preparedness and response can be found on the WHO Global Influenza Programme website {10}.  

Acknowledgements  

The WHO recommendation on vaccine composition is based on the year-round work of the WHO Global Influenza Surveillance and Response System (GISRS). We thank the National Influenza Centres (NICs) of GISRS, and non-GISRS laboratories including the World Organization for Animal Health (WOAH) and the Food and Agriculture Organization of the United Nations (FAO) Network of Expertise on Animal Influenza (OFFLU), who contributed information, clinical specimens, viruses and associated data; WHO Collaborating Centres of GISRS for their in-depth characterization and comprehensive analysis of viruses; University of Cambridge for performing antigenic cartography and phylogenetic analysis; WHO Essential Regulatory Laboratories of GISRS for their complementary virus analyses and contributions from a regulatory perspective; and laboratories involved in the production of high growth/yield reassortants as candidate vaccine viruses. We also acknowledge the GISAID Global Data Science Initiative for the EpiFluTM database and other sequence databases which were used to share gene sequences and associated information; modelling groups for virus fitness forecasting; and the Global Influenza Vaccine Effectiveness (GIVE) Collaboration for sharing estimates of influenza vaccine effectiveness on a confidential basis.  

(...)

___

{1} Recommendations for influenza vaccine composition: https://www.who.int/teams/global-influenza-programme/vaccines/who-recommendations 

{2} Description of the process of influenza vaccine virus selection and development: http://www.who.int/gb/pip/pdf_files/Fluvaccvirusselection.pdf 

{3} Vaccines in tropics and subtropics: https://www.who.int/teams/global-influenza-programme/vaccines/vaccine-in-tropics-and-subtropics 

{4} Vaccines against influenza WHO position paper – May 2022. Wkly Epidemiol Rec 2022; 97 (19): 185 - 208. Available at: https://iris.who.int/handle/10665/354264 

{5} Real-time tracking of influenza A(H1N1)pdm09 evolution: https://nextstrain.org/seasonal-flu/h1n1pdm/ha/2y?c=subclade 

{6} Real-time tracking of influenza A(H3N2) evolution: https://nextstrain.org/seasonal-flu/h3n2/ha/2y?c=subclade 

{7} Real-time tracking of influenza B/Victoria lineage evolution: https://nextstrain.org/seasonal-flu/vic/ha/2y?c=subclade 

{8} Candidate vaccine viruses: https://www.who.int/teams/global-influenza-programme/vaccines/who-recommendations/candidate-vaccine-viruses 

{9} Current respiratory virus update: https://www.who.int/teams/global-influenza-programme/surveillance-and-monitoring/influenza-updates 

{10} Global Influenza Programme: https://www.who.int/teams/global-influenza-programme 

___

Source: 

Link: https://www.who.int/publications/m/item/recommended-composition-of-influenza-virus-vaccines-for-use-in-the-2026-2027-northern-hemisphere-influenza-season

____