Historical #Pandemic and Contemporary #Influenza A Viruses Reveal #PB2 M631L as a Convergent #Adaptation to #Human ANP32

 

Abstract

Understanding the genetic changes that allow avian influenza A viruses (IAVs) to switch their natural hosts and establish productive infection in humans is important for pandemic risk assessment. Adaptations in the IAV polymerase are required to overcome species-specific restrictions imposed by host ANP32 proteins. Notably, avian virus polymerase is generally only poorly supported by human ANP32 proteins due to species-specific differences. Consequently, efficient polymerase adaptation to the binding interface of human ANP32 requires distinct amino acid changes, such as PB2 E627K. A separate adaptation, PB2 M631L, has recently been reported in mammalian-adapted IAV; however, its functional role across divergent viral lineages and its relationship to host ANP32-dependent adaptation remain incompletely defined. Here, we examine PB2 M631L in the polymerases of a 1918 pandemic strain, a recombinant contemporary H1N1pdm09, and a recent clade 2.3.4.4b H5N1 virus. Using polymerase activity and protein-interaction assays, we show that PB2 M631L enhances polymerase activity and ANP32 binding in human—but not avian—contexts, and that this effect is conserved across multiple viral backgrounds. In H1N1pdm09, PB2 M631L also increased virus replication in mammalian cells. These findings indicate that PB2 M631L contributes to enhanced polymerase compatibility with human ANP32 proteins and are consistent with a role in adaptation across multiple influenza virus lineages. Our results highlight how analysis of historical pandemic strains can inform risk assessment for future emerging viruses.

Source: 

Link: https://www.mdpi.com/2076-2607/14/4/859

____

History of Mass Transportation: The Vagónka Studénka Krokodýl (Crocodile) Autorail (1962–68)

By Vít Javůrek - http://www.mujweb.cz/www/mhd_jama/vlaky3/Krasa10/olrepc1.jpg, Public Domain, https://commons.wikimedia.org/w/index.php?curid=6311434

Source: 

Link: https://en.wikipedia.org/wiki/List_of_Czech_locomotive_classes

____

#Coronavirus Disease Research #References (by AMEDEO, April 11 '26)

 

Emerg Infect Dis

1. NILLES EJ, Paulino CT, Vasquez M, Duke W, et al
   Acute Febrile Illness Surveillance for Estimating Population Immunity, Dominican Republic, 2021.
   Emerg Infect Dis. 2026;32.
   PubMed         Abstract available
   
   

   
   Infect Control Hosp Epidemiol

2. LEUCCI AC, Sasdelli E, Caselli L, Fabbri E, et al
   Healthcare-associated infections in Italian long-term care facilities: a machine learning analysis of a 12-month cohort.
   Infect Control Hosp Epidemiol. 2026 Apr 8:1-8. doi: 10.1017/ice.2026.10413.
   PubMed         Abstract available
   
   
3. NG I, Kave B, Paynter C, Bodas C, et al
   Speech intelligibility and hearing acuity assessments of N95/P2 respirator with under-mask elastic band beard cover.
   Infect Control Hosp Epidemiol. 2025;46:1127-1133.
   PubMed         Abstract available
   
   
4. MILNER AL, Eckstein EC, Donskey CJ
   Does one size fit all for contact precautions implementation? Impact of requiring use of gloves and gowns for every room entry on personnel time, personal protective equipment costs, and carbon footprint.
   Infect Control Hosp Epidemiol. 2025;46:1161-1163.
   PubMed         Abstract available
   
   

   
   Int J Infect Dis

5. CHOI Y, Bae GH, Jeon J, Yoon J, et al
   Short-Term Mortality and the Impact of Disability Type Following COVID-19 Among Individuals with Disabilities: A Population-Based Study.
   Int J Infect Dis. 2026 Apr 4:108677. doi: 10.1016/j.ijid.2026.108677.
   PubMed         Abstract available
   
   
6. OGAWA K, Xu YS, Shimakawa Y, Chowell G, et al
   Secondary SARS-CoV-2 Transmission from Childcare Workers versus Teachers in School-Associated Screening Events, Okinawa, Japan, January-March 2022.
   Int J Infect Dis. 2026 Apr 2:108672. doi: 10.1016/j.ijid.2026.108672.
   PubMed         Abstract available
   
   
7. UNSELD M, Sturtzel B, Meyer AL, Blaise M, et al
   Real-world effectiveness and antibody responses of BNT162b2 vaccination in long-term care residents: a retrospective case-control study.
   Int J Infect Dis. 2026 Apr 2:108682. doi: 10.1016/j.ijid.2026.108682.
   PubMed         Abstract available
   
   
8. PETERSEN E, Hviid AP
   Inosine pranobex as a treatment of SARS-CoV2?
   Int J Infect Dis. 2026 Dec 31:108657. doi: 10.1016/j.ijid.2026.108657.
   PubMed        
   
   

   
   Intensive Care Med

9. GODOLPHIN PJ, Fisher DJ, Bradbury CA, Murthy S, et al
   Intermediate- versus prophylactic-dose heparin for hospitalised patients with COVID-19: an updated meta-analysis of randomised trials.
   Intensive Care Med. 2026 Apr 7. doi: 10.1007/s00134-025-08128.
   PubMed        
   
   

   
   J Infect

10. LOMHOLT FK, Valentiner-Branth P, Nielsen RT, Slotved HC, et al
    A real-time register-based surveillance system for non-invasive and invasive pneumococcal disease.
    J Infect. 2026 Apr 4:106744. doi: 10.1016/j.jinf.2026.106744.
    PubMed         Abstract available
    
    

    
    J Virol

11. JEFFERSON V, Endlich-Frazier A, Letko M
    Exploring coronavirus cell entry with functional viromics.
    J Virol. 2026 Apr 6:e0172825. doi: 10.1128/jvi.01728.
    PubMed         Abstract available
    
    
12. CHEN N, Kleine-Weber H, Alkharsah K, Winkler M, et al
    Q1020R in the spike proteins of MERS-CoV from Arabian camels confers resistance against soluble human DPP4.
    J Virol. 2026 Apr 6:e0028226. doi: 10.1128/jvi.00282.
    PubMed         Abstract available
    
    

    
    Life Sci

13. CHEN W, Ji MC, Jung E, Shin JS, et al
    Broad-spectrum coronavirus inhibition by RSV fusion inhibitors targeting six-helix bundle formation.
    Life Sci. 2026 Mar 31:124357. doi: 10.1016/j.lfs.2026.124357.
    PubMed         Abstract available
    
    

    
    Science

14. PHILLIPS KA, Horn DM, Califf RM
    Diagnostics investments and disease burden.
    Science. 2026;392:151-153.
    PubMed         Abstract available
    
    
15. KHAN S, Zhang R, Khan A, Shah A, et al
    We survived COVID-19-Are we ready for Nipah?
    Science. 2026;392:157-158.
    PubMed        

#Influenza and Other Respiratory Viruses Research #References (by AMEDEO, April 11 '26)

 

Biochemistry

1. VOGET R, Gutschow M
   Early Kinetic Characterization of SARS-CoV-2 Main Protease Inhibitors: A Review and Guidance for Biochemical Assessments.
   Biochemistry. 2026;65:860-881.
   PubMed         Abstract available
   
   

   
   Epidemiol Infect

2. MILLER AC, Boonstra DE, Cavanaugh JE, Boikos C, et al
   Disease burden associated with influenza activity at the population level.
   Epidemiol Infect. 2026 Apr 6:1-28. doi: 10.1017/S0950268826101320.
   PubMed        
   
   
3. ABUNIJELA S, Greiner T, Haas W, Kerber R, et al
   Frequency, dynamics, and duration of faecal shedding in SARS-CoV-2-infected individuals, a scoping review.
   Epidemiol Infect. 2026;154:e44.
   PubMed         Abstract available
   
   

   
   J Exp Med

4. MATHEW NR, Gailleton R, Scharf L, Schon K, et al
   Nasal CD4+ tissue-resident memory T cells provide cross-protective immunity to influenza.
   J Exp Med. 2026;223:e20251793.
   PubMed         Abstract available
   
   

   
   J Infect Dis

5. ULANOWICZ CJ, Alarcon PC, Damen MSMA, Wayland JL, et al
   Distinct inflammatory programming of thoracic cavity white adipose immune cells regulates influenza pathogenesis.
   J Infect Dis. 2026 Apr 7:jiag201. doi: 10.1093.
   PubMed         Abstract available
   
   

   
   N Engl J Med

6. PARDO-SECO J, Martinon-Torres F
   High-Dose Influenza Vaccine and Hospitalizations in Older Adults. Reply.
   N Engl J Med. 2026;394:1454.
   PubMed        
   
   
7. JOHANSEN ND, Biering-Sorensen T
   High-Dose Influenza Vaccine and Hospitalizations in Older Adults. Reply.
   N Engl J Med. 2026;394:1454.
   PubMed        
   
   
8. KANEDA Y, Fujikawa T
   High-Dose Influenza Vaccine and Hospitalizations in Older Adults.
   N Engl J Med. 2026;394:1453-1454.
   PubMed        
   
   
9. CHEN HY, Liao JC, Yong SB
   High-Dose Influenza Vaccine and Hospitalizations in Older Adults.
   N Engl J Med. 2026;394:1453.
   PubMed        
   
   

   
   Pediatrics

10. OLSON SM, Ahmad HM, Wielgosz K, Michaels MG, et al
    Pediatric Vaccine Effectiveness Against Influenza Hospitalization And Outpatient Visits: 2021-2024.
    Pediatrics. 2026 Apr 6:e2025073973. doi: 10.1542/peds.2025-073973.
    PubMed         Abstract available
    
    
11. LUCACCIONI H, Maurel M, Perez-Gimeno G, Buda S, et al
    Influenza Vaccine Effectiveness in European Primary Care Pediatric Practices: 2022-2024.
    Pediatrics. 2026 Apr 6:e2025072907. doi: 10.1542/peds.2025-072907.
    PubMed         Abstract available
    
    

    
    PLoS One

12. ANTAO V, Krueger P, Meaney C, Kwong JC, et al
    Predictors of burnout among academic family medicine faculty: Looking back to plan forward.
    PLoS One. 2026;21:e0344702.
    PubMed         Abstract available
    
    
13. SPINOS D, Beech T, Lee J, Coulson C, et al
    Referral to treatment times in the National Health Service of England: A five-year analysis of the impact of the COVID-19 Pandemic and socioeconomic deprivation and future implications for Ear, Nose and Throat service delivery.
    PLoS One. 2026;21:e0346596.
    PubMed         Abstract available
    
    
14. SHARBAYTA SS, Jo Y, Jung J, Buonomo B, et al
    The impact of human behavioral adaptation stratified by immune status on COVID-19 spread with application to South Korea.
    PLoS One. 2026;21:e0345642.
    PubMed         Abstract available
    
    
15. GRAFF I, Berger M, Schmid M, Kogej M, et al
    A decade of triage with the Manchester Triage System-The MTS big data study.
    PLoS One. 2026;21:e0344598.
    PubMed         Abstract available
    
    
16. FELLER RL, Narraway CL, Burslem DF, Colucci-Gray L, et al
    Private garden uses and associated mental well-being benefits during the first UK Covid-19 lockdown - a social media investigation.
    PLoS One. 2026;21:e0289446.
    PubMed         Abstract available
    
    
17. PAN C, Shen W
    Revisiting price linkages between London and Shanghai base metal futures markets: A time-frequency connectedness analysis.
    PLoS One. 2026;21:e0346602.
    PubMed         Abstract available
    
    

    
    Proc Natl Acad Sci U S A

18. HA J, Sharma P, Ta S, Tsukuda S, et al
    Hypoxia inducible factors regulate pneumovirus replication by enhancing innate immune sensing.
    Proc Natl Acad Sci U S A. 2026;123:e2506647123.
    PubMed         Abstract available
    
    
19. PARENTI NA, Cusic R, Renner DM, Jackson N, et al
    SARS-CoV-2 and MERS-CoV disrupt host protein synthesis via nsp1 with differential effects on the integrated stress response.
    Proc Natl Acad Sci U S A. 2026;123:e2536296123.
    PubMed         Abstract available
    
    

    
    Vaccine

20. MCCULLOUGH R, Reid A, Smyth D, O'Neill MT, et al
    Leadership matters: ward manager vaccination status influences nursing staff influenza vaccine uptake.
    Vaccine. 2026;80:128541.
    PubMed         Abstract available
    
    
21. ZHANG J, Gong C, Xu Z, Han R, et al
    Multi-mode spatial accessibility to vaccination services and its impact on influenza-related hospitalisations among older adults.
    Vaccine. 2026;80:128540.
    PubMed         Abstract available
    
    

    
    Virus Res

22. WU Y, Sun W, Xia Y, Feng Y, et al
    The influenza B virus candidate vaccine expressing H3 hemagglutinin developed in suspension MDCK cells confers protection against lethal H3N2 avian influenza in BALB/c mice.
    Virus Res. 2026;367:199722.
    PubMed         Abstract available
    

Predicting the #antigenic #evolution of seasonal #influenza viruses using phylogenetic #convergence

 

Abstract

The antigenic evolution of human seasonal influenza viruses is primarily driven by single amino acid substitutions immediately adjacent to the receptor binding site in the hemagglutinin (HA) protein. The ability to predict these substitutions would allow vaccine strains to be selected with an understanding of likely future antigenic variation. Here, we estimate the effect of HA substitutions on viral fitness using measurements of convergent evolution in a large phylogeny. We show that the substitutions which have historically caused major antigenic changes in H3N2 influenza viruses were nearly always one of few substitutions near the HA receptor binding site estimated to be under positive selection in sequences collected before the antigenic transition, based on convergent acquisition of the substitution in multiple independent lineages. Furthermore, this signal predates the establishment of the major clade containing the antigenic substitution by more than one year, so is highly informative for prospective prediction.

Competing Interest Statement

The authors have declared no competing interest.

Funder Information Declared

National Institute of Allergy and Infectious Diseases, https://ror.org/043z4tv69, 75N93021C00014

National Institutes of Health, https://ror.org/01cwqze88, R01AI165818

Medical Research Council, https://ror.org/03x94j517, MR/Y004337/1

Source: 

Link: https://www.biorxiv.org/content/10.64898/2026.04.10.717627v1

____

Respirable #Aerosol #Production and Reduction of Avian #Influenza #Transmission #Risk during #Chicken Processing, #Bangladesh

 

Abstract

In Bangladesh, influenza A(H5N1) viruses are endemic in poultry. Processing infected chickens can aerosolize viruses, increasing the risk for human infections. We evaluated particulate matter (PM2.5) mass concentration during slaughtering and defeathering methods used in live bird markets in Bangladesh to identify solutions to reduce aerosol exposure. We slaughtered 675 chickens using cones and barrels with 3 lid types and defeathered 45 chickens using a defeathering machine with 5 lid types. We interviewed 3 slaughterers to understand method preference. For slaughtering, barrels with a solid or star-cut lid reduced PM2.5 mass concentrations by 65%–73% compared with uncovered barrels. For defeathering, machines fully covered by a solid lid or lid with a hole and pivot door reduced PM2.5 mass concentrations by 50% compared with machines with no lid. Slaughterers preferred barrels covered with solid lids and defeathering machines covered with solid or hinged lids. Those methods might reduce aerosol exposure during poultry processing.

Source: 

Link: https://wwwnc.cdc.gov/eid/article/32/4/25-1878_article

____

Avian #Influenza #H9N2 - #Italy (#WHO, D.O.N., April 10 2026)

 

Situation at a glance

-- On 21 March 2026, the National International Health Regulations (IHR) Focal Point for Italy notified the World Health Organization (WHO) of the identification of a human case of avian influenza A(H9) in an adult male returning from Senegal. 

- Next generation sequencing confirmed Influenza A(H9N2). 

- According to epidemiological investigations, the patient had no known history of exposure to poultry or any person with similar symptoms prior to the onset of symptoms. 

- Authorities in Italy have implemented a series of measures aimed at monitoring, preventing and controlling the situation. 

- According to the IHR (2005), a human infection caused by a novel influenza A virus subtype is an event that has the potential for high public health impact and must be notified to the WHO. 

- This is the first imported human case of avian Influenza A(H9N2) reported in the European Region. 

- Based on currently available information, WHO assesses the current risk to the general population posed by A(H9N2) viruses as low but continues to monitor these viruses and the situation globally.

Description of the situation

-- On 21 March 2026, the National IHR Focal Point for Italy notified WHO of the identification of a human case of avian influenza A(H9) in an adult male.

-- The patient had been in Senegal for more than six months and traveled to Italy in mid-March. Upon arrival, he visited the emergency department with a fever and a persistent cough.

-- On 16 March, a bronchoalveolar lavage specimen was collected, which showed a positive Mycobacterium tuberculosis result, as well as detection of un-subtypeable influenza A virus. The patient was placed in a negative-pressure isolation room with airborne precautions. He was treated with antitubercular medication and antiviral oseltamivir. By 9 April, his condition was stable and improving.

-- On 20 March, a regional reference laboratory identified the A(H9) subtype, and on 21 March, next-generation sequencing confirmed influenza A(H9N2). Initial genetic findings suggest the infection was likely acquired from an avian source linked to Senegal. Additional samples have been sent to Italy’s National Influenza Center, where further characterization confirmed virus subtype Influenza A(H9N2), with close genetic similarity to strains previously identified in poultry in Senegal.

-- No direct exposure to animals, wildlife or rural environments was identified. There was also no reported contact with symptomatic or confirmed human cases. Further epidemiological investigations on the source of exposure are ongoing.

-- Contacts identified in Senegal were asymptomatic. All identified and traced contacts in Italy have tested negative for influenza and completed the period of active monitoring for the onset of symptoms and the quarantine required by national guidelines. They also received oseltamivir as a preventive measure. 

Epidemiology

-- Animal influenza viruses normally circulate in animals but can also infect people. Infections in humans have primarily been acquired through direct contact with infected animals or through indirect contact with contaminated environments. Depending on the original host, influenza A viruses can be classified as avian influenza, swine influenza, or other types of animal influenza viruses.

-- Avian influenza virus infections in humans may cause diseases ranging from mild upper respiratory tract infection to more severe diseases and can be fatal. Conjunctivitis, gastrointestinal symptoms, encephalitis and encephalopathy have also been reported.

-- Laboratory tests are required to diagnose human infection with influenza. WHO periodically updates technical guidance protocols for the detection of zoonotic influenza using molecular methods. 

-- Human infections with influenza A(H9) viruses have been reported from countries in Africa and Asia, where these viruses are also detected in poultry. The majority of cases of human avian influenza A(H9N2) infection have been reported from China. This is the first imported human case of avian Influenza A(H9N2) virus infection reported in the European Region. 

Public health response

-- Contact tracing procedures have been initiated, and relevant authorities in Italy, as well as internationally (National IHR Focal Point for Senegal, WHO, and European Centre for Disease Prevention and Control (ECDC)) have been informed through IHR channels. Once avian influenza was suspected, the response moved quickly from hospital-level management to regional laboratory confirmation and national coordination. Additionally, the regional surveillance system was notified, integrated within the One Health avian influenza reporting framework.

WHO risk assessment

-- Most reported human cases of A(H9N2) virus infection have been linked to exposure to infected poultry or contaminated environments, with the majority of cases experiencing mild clinical illness. Sporadic human cases following exposure to infected birds or contaminated environments can be expected since the virus remains enzootic in poultry populations. Avian influenza A(H9N2) viruses have been detected in poultry and environmental samples collected at live bird markets in Senegal and authorities in the country reported a human case of infection with an A(H9N2) virus in 2020.

-- Current epidemiological and virological evidence indicates that none of the characterized influenza A(H9N2) viruses thus far have acquired the ability for sustained transmission among humans. Thus, the likelihood of sustained human-to-human spread is low at this time. Infected individuals traveling internationally from affected areas may be identified in another country during or after arrival. However, if this were to occur, further community-level spread is considered unlikely. The risk assessment would be revisited if and when further epidemiological and virological information becomes available.

WHO advice

-- This case does not change the current WHO recommendations on public health measures and surveillance of influenza.

-- The public should avoid contact with high-risk environments such as live animal markets/farms or surfaces that might be contaminated by poultry feces. Respiratory protection is highly recommended for those handling live or dead (including slaughtering) poultry in occupational or backyard-farming settings. Good hand hygiene, i.e. frequent washing of hands or the use of alcohol-based hand sanitizer is recommended. WHO does not recommend any specific additional measures for travelers.

-- Under Article 6 of the IHR, all human infections caused by a new subtype of influenza virus are notifiable. The case definition for notification of human influenza infection caused by a new subtype under the IHR is provided here. State Parties to the IHR are required to immediately notify WHO of any laboratory-confirmed case of a human infection caused by such an influenza A virus.

-- WHO advises against the application of any travel or trade restrictions based on the current information available on this event. 

Further information

-- WHO fact sheet on Influenza (avian and other zoonotic): https://www.who.int/news-room/fact-sheets/detail/influenza-(avian-and-other-zoonotic)

-- WHO Global influenza programme, human-animal interface: https://www.who.int/teams/global-influenza-programme/avian-influenza

-- WHO Monthly Risk Assessment Summary: Influenza at the human-animal interface: https://www.who.int/teams/global-influenza-programme/avian-influenza/monthly-risk-assessment-summary

-- Protocol to investigate non-seasonal influenza and other emerging acute respiratory diseases: https://www.who.int/publications-detail-redirect/WHO-WHE-IHM-GIP-2018.2

-- World Health Organization. Public health resource pack for countries experiencing outbreaks of influenza in animals: revised guidance: https://www.who.int/publications/i/item/9789240076884

-- Implementing the integrated sentinel surveillance of influenza and other respiratory viruses of epidemic and pandemic potential by the Global Influenza Surveillance and Response System: https://www.who.int/publications/i/item/9789240101432

-- Case definitions for the four diseases requiring notification in all circumstances under the International Health Regulations (2005): https://www.who.int/publications/m/item/case-definitions-for-the-four-diseases-requiring-notification-to-who-in-all-circumstances-under-the-ihr-(2005)

-- Mosaic Respiratory Surveillance Framework: https://www.who.int/initiatives/mosaic-respiratory-surveillance-framework/

-- Practical interim guidance to reduce the risk of infection in people exposed to avian influenza viruses: https://www.who.int/publications/i/item/B09116

-- Antigenic and molecular characterization of low pathogenic avian influenza A(H9N2) viruses in sub-Saharan Africa from 2017 through 2019: https://hal.inrae.fr/hal-03213105v1

-- Genetic and Molecular Characterization of Avian Influenza A(H9N2) Viruses from Live Bird Markets (LBM) in Senegal: https://doi.org/10.3390/v17010073

-- Genetic characterization of the first detected human case of low pathogenic avian influenza A/H9N2 in sub-Saharan Africa, Senegal: https://doi.org/10.1080/22221751.2020.1763858

-- ECDC. First human case of influenza A(H9N2) infection imported in the EU: https://www.ecdc.europa.eu/en/news-events/first-human-case-influenza-ah9n2-infection-imported-eu

-- Ministry of Health, Italy. Influenza A (H9N2) virus case identified in Lombardy. Routine surveillance and prevention procedures activated: https://www.salute.gov.it/new/it/comunicato-stampa/virus-influenzale-h9n2-identificato-caso-lombardia-attivate-le-ordinarie/

__

Citable reference: World Health Organization (10 April 2026). Disease Outbreak News: Avian Influenza A(H9N2) in Italy. Available at: https://www/who.int/emergencies/disease-outbreak-news/item/2026-DON597

Source: 

Link: https://www.who.int/emergencies/disease-outbreak-news/item/2026-DON597

____

#USA, #Wastewater Data for Avian #Influenza #H5 (#CDC, April 10 '26, summary)

 

{Excerpt}

(...)

Time Period: March 29, 2026 - April 04, 2026

-- A(H5) Detection: 7 site(s) (1.6%)

-- No Detection: 430 site(s) (98.4%)

-- No samples: 125 site(s)

(...)

Source: 

Link: https://www.cdc.gov/wastewater/emerging-viruses/h5.html

____

#USA, Weekly #US #Influenza #Surveillance #Report: Key Updates for Week 13, ending April 4, 2026 (#CDC, summary)

 

(...)

Key Points

-- Seasonal influenza activity continues to decrease in most areas of the country. 

- Influenza A activity is low across all HHS regions while the amount of and trends in influenza B activity vary by region.

-- Influenza A(H3N2) viruses are the most frequently reported influenza viruses overall this season.

-- Among 2,166 influenza A(H3N2) viruses collected since September 28, 2025, that underwent additional genetic characterization at CDC, 92.8% belonged to subclade K.

-- The cumulative influenza-associated hospitalization rate overall in FluSurv-NET is the third highest since the 2010-2011 season. 

- Children younger than 18 years have the second highest cumulative hospitalization rate for that age group since the 2010-2011 season.

-- Twelve influenza-associated pediatric deaths occurring during the 2025-2026 season were reported to CDC this week, bringing the season total to 139 reported influenza-associated pediatric deaths.

-- Among children who were eligible for influenza vaccination and with known vaccination status, approximately 85% of reported pediatric deaths this season have occurred in children who were not fully vaccinated against influenza.

-- CDC's in-season severity assessment framework classified the season as moderate across all ages. 

- CDC also assesses severity by three age groups: pediatric (0-17 years), adult (18-64 years), and older adults (≥65 years). 

- At this point in the season, the pediatric age group is classified as having high severity, while both the adult and older adult age groups are classified as having moderate severity. 

- These assessments are conducted each week during the season, and the season's severity assessment can change if activity should increase again.

-- CDC estimates that there have been at least 31 million illnesses, 370,000 hospitalizations, and 23,000 deaths from flu so far this season.

-- Influenza (flu) vaccination has been shown to reduce the risk of flu and its potentially serious complications. 

- There is still time to get vaccinated against flu this season. 

- Approximately 135 million doses of influenza vaccine have been distributed in the United States this season.

-- There are prescription flu antiviral drugs that can treat flu illness; those should be started as early as possible and are especially important for patients at higher risk for flu-related complications.1

-- Influenza viruses are among several viruses contributing to respiratory disease activity. CDC provides updated, integrated information about COVID-19, flu, and respiratory syncytial virus (RSV) activity on a weekly basis.

-- No new avian influenza A(H5) infections were reported to CDC this week. To date, person-to-person transmission of influenza A(H5) viruses has not been identified in the United States.

(...)

Source: 

Link: https://www.cdc.gov/fluview/surveillance/2026-week-13.html

____

#Investigation and #impact of mammalian #adaptation markers on #H5N8 high pathogenicity avian #influenza #polymerase activity

 

Abstract

Highly pathogenic H5Nx viruses of clade 2.3.4.4b have spread worldwide, causing major economic losses and increased human exposure. Since 2020, multiple mammalian infections have been reported, raising concerns about further adaptation to mammalian hosts. We analyzed influenza A virus sequences from the Influenza Virus Database at the National Center for Biotechnology Information to identify new mammalian adaptation markers in the polymerase complex and nucleoprotein, using recursive partitioning. These markers were grouped into “proteotypes” to assess their co-occurrence and association with host origin. This analysis revealed distinct groups of proteotypes linked to mammalian adaptation, including those seen in historical and pandemic human strains. Identified mutations were introduced alone or in combination into a 2.3.4.4b H5N8 virus to evaluate their impact on polymerase activity in mammalian cells using a minigenome assay. PB1 V336I and PB2 K702R increased polymerase activity in human cells, particularly with PB2 E627K, supporting enhanced surveillance of 2.3.4.4b H5Nx viruses. These findings highlight mutation combinations relevant for enhanced surveillance of 2.3.4.4b H5Nx viruses.

Source: 

Link: https://www.nature.com/articles/s44298-026-00188-3

____

Easily Scalable, Rapidly Deployable Mechanical Ventilator for Pandemic Health Crises in Resource-Limited Areas

 

Abstract

Background: 

The COVID-19 pandemic exposed critical shortages of mechanical ventilators, particularly in low-resource settings. Disruptions in global supply chains and dependence on specialized components highlighted the need for scalable, locally manufacturing alternatives for emergency respiratory support. 

Aim: 

To describe and evaluate a simplified, supply-chain-independent mechanical ventilator assembled from widely available automotive and simple hardware components, and intended as a last-resort solution. 

Methods: 

The ventilator is based on a reciprocating air pump driven by an automotive windshield wiper motor coupled to parallel shaft bellows and readily assembled passive membrane valves, only requiring materials available from standard hardware retailers, minimal tools, and basic manual skills. Ventilator performance was assessed through bench testing using a patient model simulating severe lung disease in an adult (R=20 cmH2O*s/L, C=15 mL/cmH2O) and pediatric (R=50 cmH2O*s/L, C=10 mL/cmH2O) patients. Realistic proof of concept was performed in four mechanically ventilated 50-kg pigs. 

Results: 

The device delivered tidal volumes up to 600 mL and respiratory rates up to 45 breaths/min with PEEP up to 10 cmH₂O, covering pediatric and adult ventilation ranges. In vivo testing showed that the ventilator maintained arterial blood gases within the targeted range. Technical details for ventilator construction are provided in an open-source video tutorial. 

Discussion: 

This low-cost ventilator demonstrated adequate performance under demanding conditions. Although not a substitute for commercial intensive care ventilators, its simplicity, autonomy, and independence from fragile supply chains provide a potentially life-saving option in resource-constrained emergency scenarios.

Competing Interest Statement

The authors have declared no competing interest.

Funding Statement

This work was partially supported by Sociedad Espanola de Neumologia y Cirugia Toracica (SEPAR) (grant 1381-2022). SEPAR had no involvement other than providing funding for the independently submitted research project.

Source: 

Link: https://www.medrxiv.org/content/10.64898/2026.04.08.26350386v1

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#Species - and #variant - specific #ACE2 compatibility shapes #SARS-CoV-2 #spillover potential in North American #cervids

 

Abstract

Free-ranging white-tailed deer (WTD) are established SARS-CoV-2 reservoirs, but the susceptibility of other cervid species remains unclear. Here we integrate receptor analysis, structural modeling, and field surveillance to assess SARS-CoV-2 susceptibility across North American cervids. We identify species- and variant-specific differences in ACE2–spike compatibility. Elk ACE2 exhibits weak binding to the ancestral strain (Wuhan-Hu-1) and Delta spike receptor-binding domains (RBDs), likely due to a unique K31N substitution. In contrast, it shows stronger binding to Alpha, Beta, Gamma, and Omicron RBDs containing N501Y. Biophysical assays, gel filtration chromatography, and cryo-EM confirm stable complex formation between elk ACE2 and Alpha RBD, but not RBD from the ancestral strain. Despite weak binding, elk ACE2 supports viral entry and replication in vitro. However, surveillance revealed limited evidence of infection in the United States, contrasting with widespread WTD transmissions. These findings demonstrate that ACE2 compatibility alone is insufficient to predict reservoir potential and provide a framework for assessing species susceptibility to emerging coronaviruses.

Source: 

Link: https://www.nature.com/articles/s41467-026-71623-5

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#Norway - #Influenza A #HxNx viruses of high pathogenicity (Inf. with) (non-poultry including wild birds) (2017-) - Immediate notification

{A Canada Goose}

__

{A Greylag Goose}

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A wild Greylag Goose and a wild Canada Goose in Innlandet and Østfold Regions.

Source: 

Link: https://wahis.woah.org/#/in-review/7424

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#Preclinical evaluation of an #mRNA #vaccine developed from the first #human isolate of #bovine #H5N1

 

Highlights

• SM102 and DB-Y ionizable lipids deliver H5 mRNA vaccine with high efficiency and safety

• Vaccine-induced antibody and T cell response protect mice from H5N1 challenge

• Pre-existing H1 immunity does not diminish H5-specific immunogenicity

• Vaccine fully protects chicken against clade 2.3.4.4b/h H5 virus challenge

Summary

Given the global threat posed by H5N1 clade 2.3.4.4b avian influenza, rapid development of effective vaccines is imperative. We design an mRNA vaccine encoding hemagglutinin (HA) from A/Texas/37/2024, the first bovine-to-human strain. In murine models, both wild-type and cleavage-site-modified HA vaccines elicit robust and durable humoral immunity, along with a balanced Th1/Th2 response, conferring complete protection against lethal homologous viral challenge. The vaccine, along with the World Health Organization (WHO)-recommended candidate (A/Astrakhan/3212/2020), elicits cross-clade binding antibody responses and demonstrates improvement against specific clades at a 1 μg dose. Pre-existing H1 immunity does not diminish H5-specific immunogenicity. In avian species, the vaccine also provides full protection against lethal clades (2.3.4.4b and 2.3.4.4h). Formulated with another ionizable lipid, the vaccine elicits responses comparable to benchmark lipid nanoparticles (LNPs) and shows a favorable safety profile in rats. This work establishes a rapidly adaptable mRNA-LNP vaccine prototype for pandemic preparedness against evolving avian influenza threats.

Source: 

Link: https://www.cell.com/cell-reports-medicine/fulltext/S2666-3791(26)00119-9?_returnURL=https%3A%2F%2Flinkinghub.elsevier.com%2Fretrieve%2Fpii%2FS2666379126001199%3Fshowall%3Dtrue

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#Birth #imprinting effects on the #antibody responses of #H7N9 patients from 2013-2018 in #China

 

Abstract

Background

There is an urgent need to understand the immune correlates of protection against avian influenza viruses (AIV), where pre-existing immunity may be limited.

Methods

Here, we characterized the antibody response in 12 severely ill A(H7N9) patients and examined its association with early-life imprinting and clinical outcome.

Results

We find that A(H7N9) patients imprinted with A(H2N2) during early life show minimal H7-IgM and a rapid IgG response across diverse hemagglutinin subtypes. They also have more high avidity H7-antibodies compared to older or younger patients. Early antibody titers against seasonal H1, H3, and conserved stalk domains trend negatively with clinical severity in A(H7N9) infection, while an inverse pattern is observed following severe A(H1N1) infection, potentially suggesting a different mechanism of immune regulation between seasonal and avian influenza virus infections.

Conclusions

These data provide direct serological evidence that birth imprinting profoundly shapes the humoral immune landscape during zoonotic influenza infection and may influence subsequent disease outcome.

Source: 

Link: https://www.nature.com/articles/s43856-026-01554-1

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Genetic characterization of a novel triple - #reassortant #influenza #H1N2 virus from #pigs, #China, 2021

 

Abstract

Swine influenza virus (SIV) is a highly contagious respiratory pathogen in pigs, with bidirectional transmission posing a potential threat to human health. In this study, nasal swab samples were collected from pigs in Shandong Province, China, and yielded an H1N2 SIV strain, designated A/swine/Shandong/QD726/2021 (H1N2). Whole-genome sequencing was performed for Sw/SD/QD726/2021, and phylogenetic analysis was conducted together with 156 Chinese H1N2 reference sequences obtained from the Global Initiative on Sharing All Influenza Data (GISAID) database and the National Center for Biotechnology Information (NCBI) Influenza Virus Resource database. The results indicated that Sw/QD726/2021 represents a novel reassortant genotype (G21), with the HA gene derived from Eurasian avian-like H1N1 (EA H1N1), the NA and NS genes from triple-reassortant H1N2 (TR H1N2), and the remaining internal genes (PB2, PB1, PA, NP, M) from the 2009 pandemic H1N1 (pdm/09 H1N1). Key amino acid analysis revealed N31 in M2, responsible for adamantane resistance, and S42 in NS1, which influences viral virulence in mouse models. BALB/c mouse experiments demonstrated efficient viral replication in the lungs and nasal turbinates, accompanied by moderate body weight loss and lung lesions, indicating only moderate pathogenicity. These findings underscore the ongoing evolution of H1N2 SIV in pigs and emphasize the importance of enhanced surveillance and preventive strategies to mitigate public health risks.

Source: 

Link: https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2026.1779293/full

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Avian #Influenza #Report - From March 29 to April 4, 2026 (Wk 14) (#HK PRC SAR CHP, April 8 '26): 1 #H5N1 case in #Cambodia, 1 #H7H7 case in #Taiwan

{Excerpts}

(...)

1) H5N1

-- Date of report: 31/03/2026 

-- Country: Cambodia 

-- Province / Region: Oddar Meanchey province

-- District / City: Banteay Ampil district 

-- Sex: Male

-- Age: 3 

-- Condition at time of reporting: Hospitalised 

-- Subtype of virus  H5N1 

(...)

2) H7N7

-- Place of occurrence: Taiwan, China

-- No. of cases  (No. of deaths): 1(0)

-- Details:   

- Avian influenza A(H7N7): 

* Central Taiwan: A man in his 70s who works in a poultry farm with onset on March 20, 2026. 

* This is the first locally-acquired human case of avian influenza A(H7N7) reported in Taiwan, China. 

(...)

Source: 

Link: https://www.chp.gov.hk/files/pdf/2026_avian_influenza_report_vol22_wk14.pdf

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#Chile - #Influenza A #H5N1 viruses of high pathogenicity (Inf. with) (non-poultry including wild birds) (2017-) - Immediate notification

All [Backyard] birds at the site were culled; surveillance measures continue in the control zone. [Region: Libertador General Bernardo O'Higgins]

Source: 

Link: https://wahis.woah.org/#/in-review/7400

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#Genetic and #biological characterization of a #duck-origin clade 2.3.4.4b #H5N6 avian #influenza virus reveals partial #mammalian #adaptation

 

Highlights

• Duck-origin H5N6 virus A/Duck/Jiangsu/628/2022 shares high homology with the human strain A/Yangzhou/125/2022.

• The 628 strain shows mammalian adaptation markers: HA mutations enhance human receptors affinity and NA mutations reduce sensitivity to neuraminidase inhibitors.

• Limited airborne transmission but detectable droplet-mediated spread suggests increased mammalian transmission risk.

Abstract

Clade 2.3.4.4b H5Nx highly pathogenic avian influenza viruses (HPAIVs) have caused extensive outbreaks in poultry worldwide. H5 HPAIVs have caused sporadic but severe human infections in China, representing a persistent zoonotic threat. Here, we identified a duck-origin H5N6 HPAIV (A/Duck/Jiangsu/628/2022) through routine surveillance and assessed its biological characteristics and mammalian pathogenesis. Phylogenetic analysis revealed > 98% nucleotide identity between strain 628 and the concurrent human H5N6 strain A/Yangzhou/125/2022. Molecular characterization identified multiple mammalian adaptation markers: hemagglutinin substitutions (S137A, T160A, T192I) associated with enhanced human receptor binding; neuraminidase mutations (I117T, D198N) linked to reduced neuraminidase inhibitor susceptibility; and polymerase complex changes (PB1-D622G, PA-K142Q) conferring increased mammalian cell replication. In vitro studies demonstrated that 628 virus replicated more efficiently in mammalian than in avian cells and exhibited dual receptor-binding specificity. Mouse pathogenicity assays revealed moderate virulence with progressive lung pathology. Critically, transmission experiments confirmed both direct contact and airborne transmission capabilities of 628 in guinea pigs. These findings demonstrate that circulating H5N6 viruses have acquired partial mammalian adaptation while retaining avian fitness, significantly elevating pandemic potential. Enhanced surveillance of wild bird populations, poultry farms, and live poultry markets is urgently needed to develop effective prevention and control strategies.

Source: 

Link: https://www.sciencedirect.com/science/article/abs/pii/S037811352600146X?via%3Dihub

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Using an evolutionary epidemiological #model of #pandemics to estimate the #infection #fatality ratio for #humans infected with avian #influenza viruses

 

Abstract

The risk of highly pathogenic avian influenza virus infection to humans is challenging to estimate as many human avian influenza virus (AIV) infections are undetected because infections may be asymptomatic, symptomatic but not tested, and difficult to identify through contact tracing, as human-to-human transmission is rare. We derive equations that consider the evolutionary mechanisms that give rise to pandemics and are parameterized to be consistent with records of past pandemics. We estimate that thousands of human AIV infections occur worldwide in an average year and estimate the infection fatality ratio as 32 deaths per 10,000 infections (95% confidence interval: [9.6, 75]). This estimate is comparable to SARS-CoV-2 during the recent pandemic and higher than seasonal human influenza. We estimate that preventing animal-to-human influenza spillovers would delay pandemic emergence by several years. Preventing human infections with AIV is necessary given the high risk of severe outcomes to individuals and to reduce the risk of pandemics occurring in the future.

Competing Interest Statement

The authors have declared no competing interest.

Funding Statement

AH was supported by a Natural Sciences and Engineering Research Council of Canada Discovery Grant (RGPIN 023-05905) and a Catalyst Grant: Avian Influenza OneHealth Research, Enhanced tracking of the circulation of and risk from highly pathogenic avian influenza viruses at the human-wildlife interface from the Canadian Institutes of Health Research. JM, ML, and AH were support by an Atlantic Canada Research in the Mathematical Sciences Collaborative Research Group award.

Source: 

Link: https://www.medrxiv.org/content/10.64898/2026.01.21.26344526v2

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