#WHO emergency #guidance on use of licensed #Ebola {Zaire} #vaccine during #Bundibugyo virus disease #outbreaks - Interim guidance 31 August 2026 (Summary)

 

Context

    Ervebo® is currently the only licensed Ebola vaccine available. Ervebo®  (rVSV-EBOV-GP) is a live, recombinant vesicular stomatitis virus (rVSV)-based vaccine licensed that was prequalified by the World Health Organization (WHO) in 2019 for the prevention of Ebola virus disease caused by Ebola virus (EBOV, species Orthoebolavirus zairense, previously known as Zaire ebolavirus) in individuals aged one year or older. It is not licensed for use against Bundibugyo virus (BDBV) and therefore the use of Ervebo® against BDBV constitutes off-label use{1} BDBV and EBOV cause Ebola disease that is  clinically similar but are genetically and antigenically distinct virus species. Their  glycoproteins share approximately only 60–65% amino acid sequence  identity, a distinction that is particularly relevant for vaccination because currently  available Ebola vaccines, including Ervebo®, target the viral  glycoprotein.

    Consequently, although Ervebo® is highly effective against EBOV, the  extent to which Ervebo®-induced immunity provides clinically meaningful  protection against BDBV remains unknown. (1)

    On 19 August 2026 (2), the Strategic Advisory Group of Experts on Immunization (SAGE) reviewed and deliberated on the additional evidence that  had become available following the publication of the WHO emergency guidance  on the use of licensed Ebola virus vaccine during Bundibugyo virus disease  outbreaks, 28 May 2026. (3)

    The BDBV outbreak in the Democratic Republic of the Congo has spread  substantially, with continued transmission and high mortality, creating an urgent  need to strengthen outbreak response and reduce preventable deaths. (4) The  severity of the disease and evolving epidemiological situation increases the  imperative to consider all potentially beneficial interventions, while at the same  time carefully weighing the unknown efficacy of Ervebo® against BDBV, and resultant risks.

    A ring vaccination randomized controlled trial (henceforth referred to as  ring RCT) of Ervebo® and BDBV-specific vaccine candidates is planned to be  conducted in the Democratic Republic of the Congo as a matter of urgency. (5) If  well designed and rigorously implemented, the trial would provide the critical  evidence currently lacking on the efficacy of Ervebo® against BDBV.

Assessment of additional evidence on Ervebo® performance against BDBV since May 2026

    Findings from an increased, albeit still limited, number of studies  conducted to date in nonhuman primates and ferrets suggest some  protection by Ervebo® against BDBV-related mortality, while showing little or no  protection against viraemia and clinical disease (...).

    In the absence of an established correlate or surrogate of  protection  against BDBV, the extent to which findings from animal challenge  models (disease and laboratory-based immunological studies) can predict  protection in humans remains unknown. 

    Available human immunogenicity data regarding potential cross-protection  conferred by Ervebo® against BDBV showed that Ervebo® induces cross-reactive BDBV glycoproteinbinding antibodies which are at levels  approximately 5-fold lower than against EBOV, and that cross-neutralization of  BDBV pseudoviruses with neutralizing titres are approximately 3.5–4-fold lower  than against EBOV (...).

    No Ervebo® vaccine efficacy data against BDBV in humans have been  generated yet. 

    There are a small number of anecdotal reports of previously vaccinated  health care workers who subsequently developed BDBV disease and survived.  However, no conclusions regarding vaccine efficacy or effectiveness can be drawn  from these observations because of the very small sample size, the absence of an  appropriate comparator group, the potential for substantial bias, non-systematic  data collection, and the resulting considerable statistical uncertainty.

    Overall, the limited data and anecdotal reports are suggestive of some  protection against BDBV-related mortality and are consistent in trending towards  some as yet unquantified benefit.

    In conclusion, the available data remain insufficient to determine whether Ervebo® provides any clinically meaningful protection against  BDBV in humans or to reliably estimate the magnitude of such protection,  including protection against infection, disease, severe disease or death.

Benefit–risk considerations regarding off-label use of Ervebo® in the context of unknown efficacy against BDBV

    There is currently clinical equipoise regarding the efficacy of Ervebo®  against    BDBV. 

    Vaccine efficacy in humans remains to be established and could range  from high efficacy, with substantial clinical and public health benefit, through  moderate or partial efficacy, to limited or negligible efficacy, with little or no  meaningful protection. The lower limit of the range of potential effects may even  include harm. The potential ratio of benefits and risks of broader use therefore  differ considerably depending on where within this range the true efficacy ultimately lies.

    If efficacy is high or clinically meaningful, broader use while the ring RCT  is underway could potentially reduce severe disease and deaths and, if the vaccine  also protects against infection and transmission, contribute to outbreak  control. In a context where other medical countermeasures remain limited, earlier  access could provide populations at high risk with a vaccine that has a  well-characterized safety profile, while BDBV-specific vaccines remain under  evaluation and are not yet available for use. Use within appropriately designed  research frameworks could also generate complementary real-world effectiveness  data. In addition, vaccinated individuals would be expected to benefit from  protection against Ebola virus disease should they subsequently be exposed during a future EBOV outbreak.

    Conversely, if efficacy is low, negligible or absent, the balance of benefits  and risks would be substantially less favourable. Considerable financial, logistic  and human resources would be diverted to an intervention providing little or no  clinical or public health benefit. These resources could otherwise support  outbreak-control measures of established effectiveness, including surveillance,  contact tracing, timely testing and case detection, isolation, infection prevention  and control, and safe and dignified burials. These resources could also have been better invested in the development of BDBV-specific vaccines.

    A scenario in which Ervebo® provides meaningful protection against  severe disease or death, but limited or no protection against infection, viraemia or  onward transmission, would require careful consideration. Protection against  severe disease or death would constitute an important individual and public health  benefit, even in the absence of substantial effects on infection or  transmission. However, vaccination could then reduce morbidity and mortality without necessarily interrupting transmission. If this efficacy profile is  not clearly understood and communicated, vaccination could lead to false  reassurance among vaccinated individuals, communities and responders,  potentially reducing adherence to established outbreak-control measures. Such  behavioural changes could offset some of the benefits of vaccination and, if  infection and onward transmission are not sufficiently reduced, could contribute to continued transmission and potentially prolong or exacerbate the outbreak.

    If efficacy proves limited or negligible, substantial numbers of  breakthrough cases or deaths could also undermine public trust in the outbreak  response and confidence in Ebola vaccines, vaccination programmes generally,  and the health sector more broadly. Once broader vaccination has commenced, a  subsequent decision to restrict or discontinue Ervebo® use, if the evidence shows  limited efficacy, could itself create important communication and trust challenges.

    There are also important evidence-generation trade-offs. The use of  Ervebo® outside rigorous research protocols could interfere with the feasibility,  recruitment, implementation and scientific integrity of studies, particularly the ring  RCT, designed to establish vaccine efficacy for Ervebo® and BDBV-specific  vaccine candidates (which are expected to have the potential for better  performance against BDBV). This could delay the generation of the robust evidence needed to guide policy. Observational Ervebo® effectiveness  studies could provide useful complementary information but are inherently more  susceptible to bias and confounding than RCTs and may therefore be more difficult  to interpret or insufficiently robust to resolve the central question of  efficacy. Vaccine effectiveness (VE) studies of vaccines with modest efficacy are  particularly prone to these limitations. Hence the value of any observational study  depends partly on the extent to which its design can ensure that uptake of the  intervention is as close to random as possible and that outcome data are collected  systematically from all participants allowing comparable analysis, thereby reducing selection and information biases. Conversely, if the ring RCT  demonstrates clinically meaningful efficacy of Ervebo® and/or BDBV-specific  vaccine candidates, such a trial would provide a strong basis for rapidly updating  policy and expanding vaccine(s) use to benefit the wider population.

    Extensive reliance on Ervebo® could potentially affect community willingness to participate in future studies or receive BDBV-specific vaccines,  which become especially important if the efficacy of Ervebo® against BDBV is insufficient.

    Finally, widespread deployment would have implications for global vaccine security. Largescale use of available Ervebo® doses against BDBV could  temporarily deplete the International Coordinating Group on Vaccine  Provision stockpile and potentially compromise timely access to vaccine for  response to a future outbreak caused by EBOV, against which Ervebo® has demonstrated efficacy and is licensed.

    Taken together, the uncertainties described above reinforce the importance of obtaining robust efficacy data as rapidly as possible while  carefully weighing the potential benefit of any broader use against its potential negative consequences.

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{1} Use of a vaccine for an unapproved indication (not described in the approved  labelling) or in an unapproved age group, dosage, or route of administration. 

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© World Health Organization 2026. Some rights reserved. This work is available under the CC BY-NC-SA 3.0 IGO licence.

Suggested citation. WHO emergency guidance on the use of licensed Ebola vaccine during Bundibugyo virus disease outbreaks, 31 August 2026. Geneva:  World Health Organization; 2026. https://doi.org/10.2471/B09884

Source: 

Link: https://doi.org/10.2471/B09884

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Early Action #Review of #Detection, Notification, and #Response Timeliness during Cross-Border #Bundibugyo Virus Disease #Outbreak, #Uganda, 2026

 

Abstract

Bundibugyo virus disease (BVD), an Ebola virus species with no licensed vaccine or therapeutic, reemerged in May 2026 as a cross-border outbreak in Uganda and the Democratic Republic of the Congo. During a 2-day workshop, July 8–9, 2026, we conducted an early action review of the outbreak response using the 7-1-7 framework (7 days to detect, 1 day to notify, 7 days to complete early response actions) to assess timeliness and identify bottlenecks and enablers across 9 response pillars. Uganda declared its outbreak on May 15, 2026; by July 8, the country had recorded 20 confirmed cases (15 imported, 5 locally transmitted) and a case-fatality rate of 15%. Uganda met all 3 targets: detection in 6 days, notification in <1 day, and response completion in 2 days. Low clinical suspicion, cross-border data-sharing gaps, fragmented digital systems, and delayed community engagement were common bottlenecks; strong leadership and coordination structures were most cited enablers.

Source: 

Link: https://wwwnc.cdc.gov/eid/article/32/10/26-1411_article

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#France - High pathogenicity avian #influenza #H5N1 viruses (Inf. with) (#poultry) - Immediate notification

 

A farm with vaccinated ducks in Maine-et-Loire Region.

Source: 

Link: https://wahis.woah.org/#/in-review/7800

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Immunogen selection and prior #immunity shape #antibody breadth following immunisation with avian #H5 #hemagglutinin

 

Abstract

Avian influenza A viruses pose a persistent zoonotic threat to humans owing to their expanding host range and high case fatality rates. In particular, viruses from the 2.3.4.4b clade of the H5 subtype have now been detected in over 60 mammalian species, raising serious pandemic concerns. Understanding immune recognition of the H5 hemagglutinin (HA) is therefore critical for effective vaccine design and pandemic preparedness. To understand the breadth of cross-recognition induced by different H5 strains, we selected genetically diverse H5 human isolates from 2003-2023 and assessed neutralising antibody responses elicited by adjuvanted recombinant HA protein-based vaccines in C57BL/6 mice. Neutralisation activity of sera was determined against seven H5 HA variants using pseudotyped viruses and a PR8-reassortant virus in micro-neutralisation assays. Our results showed a wide variety of cross-strain neutralisation across H5 HA antigen variants. The conventional vaccine strain A/Indonesia/05/2005 displayed narrow activity against emerging clade 2.3.4.4b viruses, whereas ancestral variants exhibited cross-neutralisation profiles showing a diversity of breath but with limited potency. Polyvalent H5 HA formulations and nanoparticle-displayed H5 HA platforms substantially broadened cross-neutralisation against diverse H5 strains. To examine the impact of pre-existing immunity on H5 vaccine immunogenicity in mouse models, mice were primed with either seasonal influenza infection or quadrivalent influenza vaccine (QIV) prior to H5 HA immunisation. QIV pre-vaccination, but not prior influenza infection, enhanced subsequent neutralizing responses towards A/Fujian-Sanyuan/21099/2017 (clade 2.3.4.4b) H5. Collectively, our results demonstrate that immunogen selection and prior immunity shape antibody breadth following immunisation with avian A(H5) hemagglutinin.

Source: 

Link: https://www.biorxiv.org/content/10.64898/2026.09.01.748495v1

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#Bundibugyo Virus Disease #Outbreak, #DRC, #Uganda - Situation #Report 16, Data as of 30 August 2026 (WHO, summary): 6,100 cases & 2,950 deaths in DRC

 

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Event description

Democratic Republic of the Congo

    The Bundibugyo virus disease (BVD) outbreak in the Democratic Republic of  the Congo continues to evolve, characterized by sustained transmission, high mortality and continued geographic expansion. 

    The epidemiological picture is increasingly heterogeneous, with  persistent transmission in established hotspots in Ituri, intensifying transmission  in parts of Nord-Kivu and Haut-Uélé, and the continued emergence of cases in  previously unaffected health zones. 

    Since External Situation Report #15, a further 516 confirmed cases and 270 confirmed deaths have been reported, bringing the cumulative total to 6100 confirmed cases, including 2950 deaths (CFR 48.4%), as of 30 August 2026. 

    The number of affected health zones has increased from 57 to 60 across  six provinces, with Biena and Manguredjipa in Nord-Kivu and Ganga in  Bas-Uélé newly affected since the previous update. 

    Ituri remains the epicentre, accounting for 82.2% of cumulative confirmed  cases, although continued expansion in Nord-Kivu and Bas-Uélé underscores the  increasingly dispersed geographic pattern of the outbreak.

    During the most recent 21 days (10 – 30 August 2026), 1719 confirmed cases were reported nationally. Compared with 1958 cases during the preceding 21-day period (20 July – 9 August 2026), this represents a decrease of 239 cases (−12.2%). This decline should be interpreted cautiously given  potential reporting delays and retrospective data reconciliation and does not, on its own, establish that transmission is declining. 

    The national trend continues to mask substantial geographic heterogeneity.  

    Reported cases declined by 21.6% in Ituri, from 1601 to 1255, but  increased by 33.2% in Nord-Kivu, from 256 to 341, and by 12.4% in Haut- Uelé, from 97 to 109. Consequently, Ituri’s contribution to newly reported cases  fell from 81.8% to 73.0%, while Nord-Kivu’s contribution increased from 13.1% to 19.8% and HautUélé’s from 5.0% to 6.3%. 

    A further 10 cases were reported in Tshopo and four in the newly affected  Bas-Uélé during the latest period. 

    The latest provincial cumulative totals confirm that Ituri remains the  principal focus, but transmission is becoming progressively less concentrated in  the original epicentre.

    During the same period, 939 confirmed deaths were reported nationally,  compared with 1044 deaths during the preceding 21 days, representing a  decrease of 105 deaths (−10.1%). This decline was again driven predominantly  by Ituri, where reported deaths decreased from 809 to 654 (−19.2%). 

    In contrast, deaths increased from 197 to 228 (+15.7%) in Nord-Kivu and  from 37 to 50 (+35.1%) in Haut-Uélé. Consequently, Ituri’s contribution to newly  reported deaths declined from 77.5% to 69.6%, while Nord-Kivu’s increased from  18.9% to 24.3% and Haut-Uélé’s from 3.5% to 5.3%. Tshopo reported four  deaths and Bas-Uélé three during the latest period. Taken together, the decline in  both reported cases and deaths suggests a reduction in the nationally reported  disease burden. However, reporting delays and retrospective data reconciliation  limit interpretation, while simultaneous increases in cases and deaths in Nord-Kivu and Haut-Uélé demonstrate that transmission remains substantial and is  continuing to redistribute geographically.

Figure 1. Daily trend in confirmed Bundibugyo virus disease cases, with seven-day moving average, by date of report, Democratic Republic of the Congo, as of 30 August 2026

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    At health-zone level, the national decline masks substantial  heterogeneity across established and emerging transmission foci. Of the 60  health zones affected since the start of the outbreak, comparison of the two  consecutive 21-day periods shows that reported cases increased in 20 health  zones and decreased in 22. 

    

    A further 10 previously affected health zones reported no confirmed  cases during the latest 21 days (Adja, Kambala, Logo and Mahagi in Ituri; Goma  and Lubero in Nord-Kivu; Rungu in Haut-Uélé; Lubunga and Wanie-Rukula in  Tshopo; and Miti-Murhesa in Sud-Kivu), while incidence was unchanged in one health zone (Bafwasende, Tshopo). 

    Seven health zones were newly affected during the latest 21-day period. 

    In Ituri, the reduction was driven particularly by Mongbwalu, where  reported cases declined from 183 to 44 (−139; −76.0%), and Nizi, from 277 to  182 (−95; −34.3%). 

    Cases also declined in Lita, from 84 to 61 (−23; −27.4%), and Rwampara,  from 242 to 191 (−51; −21.1%). 

    Bunia, however, remained the largest active focus and increased from  363 to 383 (+20; +5.5%). Other Ituri health zones also recorded increases,  notably Mangala, from 53 to 126 (+73; +137.7%), Nia-Nia, from 61 to 80 (+19;  +31.1%), and Bambu, from 31 to 66 (+35; +112.9%). 

    Outside Ituri, transmission  continued to intensify in Nord-Kivu,  particularly in Katwa, where cases increased from 112 to 165 (+53;  +47.3%), and Beni, from 30 to 66 (+36; +120.0%). In Haut-Uélé, Isiro increased  from 18 to 51 (+33; +183.3%) and Wamba from 8 to 48 (+40; +500.0%). 

    These patterns show that the overall decline in Ituri is being driven by  substantial reductions in several established hotspots rather than a uniform  decrease across the province; Bunia remains highly active, while other foci within  Ituri and in Nord-Kivu and Haut-Uélé continue to expand. 

    Reported deaths show a similar geographic redistribution but with  important differences from the case trends. In Ituri, deaths declined substantially  in several established hotspots, including Mongbwalu, Nizi, Lita and Rwampara,  consistent with the reduction in reported cases in these areas. However, mortality  remained substantial in Bunia, while increases in cases in Mangala, Nia-Nia and  Bambu indicate continued transmission within the province despite the overall  decline.

    In Nord-Kivu, increasing mortality accompanied the continued growth  of the Katwa and Beni foci, while in Haut-Uélé the increase in deaths was  concentrated particularly in Isiro and Wamba. 

    Overall, the health-zone  pattern reinforces the provincial analysis:  transmission is declining in several formerly dominant Ituri hotspots but is not  declining uniformly. 

    Interpretation of health-zone mortality trends in Ituri should however  remain cautious, particularly because cumulative death counts have undergone  continuing reconciliation and redistribution across health zones, with 329 confirmed deaths in Ituri awaiting allocation to health zone as of 30 August  2026. 

    Mortality remains high, with 270 confirmed deaths reported during the  last seven days, including 171 (63.3%) in the community and 99 (36.7%) in BVD  treatment facilities. 

    The persistently high proportion of community deaths (defined  as both  deaths at home and at non-BVD health facilities) highlights continued challenges  with early detection, referral and timely access to treatment, while mortality in  BVD treatment facilities may reflect late presentation, quality of care and patient  vulnerabilities, including age, malnutrition and comorbidities; further analysis to  understand the risk factors is underway.

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Uganda and France

    Both Uganda and France have not reported new cases for more than 42  days. The outbreak in these countries is considered over by WHO’s norm of 42  days without any cases. 

Risk Assessment

    According to WHO’s latest Rapid Risk Assessment as of 20 August 2026, the risk of further spread remains very high within the Democratic  Republic of the Congo and high for neighbouring countries sharing land  borders with the country. 

    The assessment reflects sustained transmission, continued geographic  expansion, high mortality, population mobility, insecurity and persistent response  challenges. The risk is considered low elsewhere in Africa and globally. 

    The second IHR Emergency Committee, convened on 18 August 2026, also  reviewed the evolving situation and emphasized that the outbreak remains far  from controlled, and continues to constitute a Public Health Emergency of International Concern.

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Situation interpretation

    The overall decline in reported cases and deaths is encouraging but  does not yet indicate that the outbreak is under control. Transmission is becoming  increasingly heterogeneous, with reductions in several established  hotspots in Ituri occurring alongside expanding transmission in Nord-Kivu and  Haut-Uélé and continued emergence of new affected health zones. 

    Persistently high mortality, particularly community deaths, together with  gaps in contact follow-up, referral and treatment capacity, infection  prevention and control, and community acceptance, continue to create opportunities for transmission. 

    The response should therefore become more anticipatory and  geographically targeted, rapidly shifting surveillance, contact tracing, clinical care,  IPC, community engagement, workforce and logistical capacity towards emerging and intensifying hotspots, while sustaining interventions in areas where transmission is declining to prevent resurgence.

Source: 

Link: https://iris.who.int/bitstreams/22a50ebd-a676-4a82-a40e-7feae57dc1fe/download

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Characteristics and Monitoring of the 2026 #Outbreak of #Ebola Disease Caused by #Bundibugyo Virus — #DRC, August 2026 (MMWR, edited)

 

Summary

    ° What is already known about this topic?

        § In May 2026, an outbreak of Ebola disease caused by Bundibugyo virus was identified in the Democratic Republic of the Congo.

    ° What is added by this report?

        § This ongoing outbreak is now the second largest Ebola outbreak in history. The targets for five critical public health response indicators (case detection alerts, contact tracing, laboratory testing, isolation of infected persons, and safe and dignified burials) have not yet been met, and the outbreak continues to expand rapidly.

    ° What are the implications for public health practice?

        § Substantial improvements in established outbreak control measures are crucial to rapidly detect and diagnose cases and isolate and provide treatment for infected persons, prevent funeral-associated transmission to prevent additional spread, and control this rapidly expanding outbreak.

    The Democratic Republic of the Congo (DRC) Ministry of Public Health declared an Ebola outbreak on May 15, 2026. Two days later, CDC activated its Emergency Operations Center as part of the U.S. government response to this rapidly growing outbreak. This report describes the epidemiologic characteristics and monitoring of the ongoing outbreak in DRC.

Investigation and Outcomes

Background

    The 2026 Ebola DRC outbreak caused by Bundibugyo virus is now the second largest Ebola outbreak ever recorded. As of August 21, 2026, DRC reported 5,458 confirmed cases and 2,606 (48%) confirmed deaths. 

    Compared with previous Ebola outbreaks, the increase in cases in DRC is unprecedented, with approximately 5,000 cases in 100 days (Ebola Outbreak: Current Situation | CDC). 

    Cases have been reported from six of the 26 DRC provinces (Bas-Uélé, Haut-Uélé, Ituri, North Kivu, South Kivu, and Tshop), affecting 57 of 151 health zones in the affected provinces. 

    Ituri province remains the outbreak epicenter, accounting for 84% of reported cases. 

    Strategies known to control Ebola outbreaks include community-based surveillance, case detection alert notifications,* rapid and in-depth case investigations, identification and monitoring of contacts, infection control measures (e.g., prompt isolation of persons with suspected or confirmed Bundibugyo virus disease [BVD]), rapid diagnostic testing, mortality surveillance, and safe and dignified burials (SDBs).†

Data Source

    Operational indicators for five domains have been generated based on experience with previous Ebola outbreaks, including DRC’s 2018 outbreak. Targets reflect the levels necessary to end the outbreak. 

    The DRC Ministry of Public Health prepares publicly available daily situation reports, and CDC abstracts data from these reports to evaluate the established indicators each day. Indicator data are monitored over time to assess the outbreak trajectory. This activity was reviewed by CDC, deemed not research, and conducted consistent with applicable federal law and CDC policy.§

Operational Indicator Analysis

    Nearly all operational indicators remain below identified targets (...). 

    Operational indicator values were calculated for the 21-day period of July 31–August 21. 

    The average percentage of alerts investigated within 24 hours (last reported August 5, 2026) was 83% (target = >90%). 

    An average of 10.6 contacts were identified per confirmed case (target = ≥20), suggesting underreporting and underascertainment of case contacts. 

    The percentage of confirmed new cases previously identified as known contacts (last reported July 12, 2026) was 15%–20% (target = >90%); this suggests that most cases are occurring outside known transmission chains. 

    In addition, more than one half (59%) of confirmed Ebola deaths are occurring outside an Ebola treatment unit (ETU) (target = 0%), suggesting insufficient ETU capacity, fear of ETUs, and ongoing spread through unidentified transmission chains. 

    Laboratory testing was performed for 72% of validated alerts (target = >90%), indicating that a substantial number of suspected cases remain untested. 

    Test positivity was 24%, with a target of 0%. 

    Although the national ETU bed occupancy was 64%, meeting the target of <80%, occupancy varied substantially by health zone, with some facilities unable to isolate all infected persons and reporting occupancies as high as 140%. 

    Fewer than one half (49%) of affected health zones had at least one SDB team (target = 100%). 

    Current data were not available for several response indicators, such as percentage of persons with confirmed BVD receiving prompt isolation (target = >90%) and percentage of deaths with SDBs (target = 100%), underscoring ongoing data gaps in this complex public health response.

Preliminary Conclusions and Actions

    As of August 21, 2026, most operational indicator measures remained below established response targets, and data for others were unavailable, indicating gaps in surveillance, contact tracing, laboratory testing, health care–seeking, isolation, and SDB capacity that limit control of the ongoing outbreak. 

    These missing data and operational gaps, together with continued geographic expansion of the outbreak, a high percentage of deaths occurring outside ETUs, and a low percentage of cases among persons previously identified as contacts, indicate uncontrolled expansion of the outbreak. 

    Public health response activities are complicated by a protracted complex humanitarian emergency in the eastern part of DRC, including armed conflict, limited health infrastructure, population displacement and mobility, and constraints on access to affected communities.

    Containment and control of the 2026 Ebola disease outbreak requires integration and coordination of at least five response areas: 

    1) expansion of community-based surveillance systems ensuring rapid investigation of alerts; 

    2) improvements in contact tracing completeness and timeliness; 

    3) expansion of treatment and isolation capacity in affected health zones; 

    4) increased laboratory testing capacity, enabling prompt case identification; and 

    5) ensuring SDBs in affected health zones.

    

    In addition, collecting robust, high-quality data regarding these operational actions is essential at the health zone level; CDC’s continued support to the DRC Ministry of Public Health and partners with improving data collection is critical. 

    Collecting data at the level of the health zone facilitates timely local outbreak response decisions. 

    Rapidly enhancing international humanitarian coordination and mobilizing global technical, operational, and other needed support are critical for accelerating the response and controlling the outbreak.

CDC 2026 Ebola Response International Epidemiology and Laboratory Task Force

Christine Atherstone, Amy Boore, Vance Brown, Jonathan Bryant-Genevier, Nirma Bustamante, Maestro Evans, James Fuller, Timothee Kinkela, John D. Klena, Thomas C. McHale, Elissa Meites, Emmanuel A. Mensah, Mpingulu Minlangu, Pierre Muhoza, Mike Park, Jaymin Patel, Satish K. Pillai, Anne Purfield, Logan Ray, Jessica N. Ricaldi, Katrin S. Sadigh, Dean Sayre, Trevor Shoemaker, Rachel Snyder, Christina Spiropoulou, Leisel Talley, Alison Todres, Sebastien Tshipamba, Amy Whitesell, Hailey Whitmire, Kristina Wielgosz, Emily Zielinski-Gutierrez, CDC; Democratic Republic of the Congo, Ministry of Public Health.

Corresponding author: Sascha Ellington, frk5@cdc.gov.

Source: 

Link: http://dx.doi.org/10.15585/mmwr.mm7535e1

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#Genome-informed structural #analysis of #polymerase and glycoprotein #adaptation in #H5N1 clade 2.3.4.4b

 

Abstract

Importance

Understanding the molecular mechanisms driving H5N1 clade 2.3.4.4b is critical for pandemic preparedness.

Objective

To characterize the molecular drivers of viral fitness and mammalian adaptability in recent H5N1 viruses by integrating evolutionary dynamics with structural simulations.

Methods

This study analyzed 2,398 H5Nx genomes (2000–2024) through phylogenetic and selective pressure analyses. HA/NA structures were predicted with AlphaFold 3 and evaluated by AutoDock4 docking, whereas polymerase–ANP32A/B complexes were modeled using template-based methods and their binding free energies were estimated using MM/GBSA. Polymerase–ANP32E complexes were predicted with AlphaFold 3 and similarly evaluated by MM/GBSA. The binding affinities (ΔG) for the sialic acid (SA) receptors and human ANP32 proteins were quantified through molecular mechanics/generalized born surface area calculations.

Results

Clade 2.3.4.4b showed significant antigenic drift in the HA receptor binding site, reducing affinity for α2,3-SA and α2,6-SA receptors. On the other hand, the emergence of a full-length stalk N1 NA with second sialic acid-binding site mutations (e.g., N366S) compensated for reduced HA affinity by enhancing the NA binding stability. In the polymerase complex, both the PB2-627E/631L variant (−144.00 kcal/mol; unadjusted p = 0.0058) and the known mammalian-adaptive 627K/631M variant (−144.67 kcal/mol; unadjusted p = 0.0165) showed more favorable predicted human ANP32B binding free energies than the ancestral 627E/631M state (−136.46 kcal/mol).

Conclusions and Relevance

The co-occurrence of HA, NA, PB1, and PB2 signatures was associated with clade expansion and produced structural predictions consistent with altered receptor or ANP32 interactions; experimental validation is required before inferring effects on fitness or zoonotic risk.

Source: 

Link: https://vetsci.org/DOIx.php?id=10.4142/jvs.26088

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Avian #Influenza #Report: August 23 - 29 '26 (Wk 35) (CHP, HK SAR September 1, 2026): 1 New #Human Infection with #H9N2 virus in Anhui, 20 cases so far this year

 

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Avian influenza A(H9N2):

    ° Anhui Province {China}:

        § A three-year-old boy with onset on August 3, 2026.

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Source: Centre for Health Protection, Hong Kong PRC SAR, https://www.chp.gov.hk/en/index.html

Link: https://www.chp.gov.hk/files/pdf/2026_avian_influenza_report_vol22_wk35.pdf

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The first high pathogenicity avian #influenza #H5N1 clade 2.3.4.4b incursions in Hunter New England region, NSW, #Australia, June–July 2026

 

Abstract

Two incursions of high pathogenicity avian influenza (HPAI) A(H5N1) clade 2.3.4.4b in vagrant birds were identified in the Hunter New England region of New South Wales, Australia on 28 June 2026 and 10 July 2026. These were the first detections of the virus in New South Wales and occurred shortly after the first Australian detection in June 2026. The Hunter New England Population Health Unit managed human contacts of the infected birds using a contact management system designed and purpose-built by the Unit. We report on the public health response and opportunities for improvement.

Source: 

Link: https://ojs.cdi.cdc.gov.au/index.php/cdi/article/view/3492

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#Report on #influenza viruses received and tested by the #Melbourne #WHO Collaborating Centre for Reference and Research on Influenza during 2025

 

Abstract

As part of its role in the World Health Organization (WHO) Global Influenza Surveillance and Response System (GISRS), the WHO Collaborating Centre for Reference and Research on Influenza in Melbourne (the Centre) received 13,817 human influenza-positive samples during 2025. Viruses were analysed for their antigenic, genetic, and antiviral susceptibility properties. Selected viruses were propagated in qualified cells or embryonated hens’ eggs for potential use in seasonal influenza virus vaccines. Of the 13,817 samples received or processed, influenza A(H1N1)pdm09 viruses predominated, accounting for 46.1% of samples, compared to 21.2% for A(H3N2) viruses and 19.5% for influenza B viruses; one influenza C virus was received. Among viruses analysed at the Centre, the majority of A(H1N1)pdm09 (> 99%) and influenza B (98%) viruses were antigenically similar to their respective WHO recommended vaccine strains for the Southern Hemisphere in 2025. In contrast, only 43% of A(H3N2) viruses were antigenically similar to their respective WHO recommended vaccine strains. Of 3,307 samples tested for susceptibility to the neuraminidase inhibitors oseltamivir and zanamivir, 37 A(H1N1)pdm09 viruses showed highly reduced inhibition by oseltamivir and no influenza viruses tested showed highly reduced inhibition by zanamivir. Of 5,080 samples with sequencing of the polymerase acidic (PA) gene, no genetic markers associated with highly reduced susceptibility to baloxavir marboxil were identified.

Source: 

Link: https://ojs.cdi.cdc.gov.au/index.php/cdi/article/view/3489

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#Nirmatrelvir–ritonavir targeting viral #persistence in post-COVID-19 condition (long #COVID) in the #USA (RECOVER-VITAL): a randomised, double-blind, placebo-controlled, phase 2 trial

 

Summary

Background

Post-acute sequelae of SARS-CoV-2 infection, more commonly known as long COVID, has emerged as a major health problem. The pathogenesis of long COVID is unknown, but among the leading hypotheses is viral persistence. We aimed to investigate whether the use of the SARS-CoV-2 antiviral nirmatrelvir–ritonavir improved long COVID symptoms.

Methods

We conducted a double-blind, placebo-controlled, randomised trial involving adults who had developed persistent symptoms (≥12 weeks) associated with three major symptom phenotypes (cognitive, autonomic, or exercise) after acute SARS-CoV-2 infection at 69 US sites. Participants were eligible if they were 18 years or older and had a previous suspected, probable, or confirmed SARS-CoV-2 infection, as defined by the Pan American Health Organization. Eligible participants were also required to have either at least two moderate symptoms from the same phenotype or one severe phenotype-associated symptom, as identified with the Cluster Targeted COVID-19 Symptom Questions. Participants were randomly allocated in a double-blind manner in a 1:1:1 ratio using permuted blocks of size 30 to receive either 15 days of active intervention followed by 10 days of placebo (300 mg nirmatrelvir–100 mg ritonavir twice daily, then 100 mg ritonavir–placebo); 25 days of active intervention (300 mg nirmatrelvir–100 mg ritonavir twice daily); or 25 days of placebo–ritonavir (100 mg ritonavir–placebo). A clinically significant change in patient-reported outcomes at day 90 comprised the primary endpoint: Patient-Reported Outcomes Measurement Information System Cognitive Function Short Form 8a, Orthostatic Hypotension Questionnaire question 1, and a modified version of the DePaul Symptom Questionnaire Post-Exertional Malaise short form. Secondary outcomes were phenotype-specific performance measures. The study was registered at ClinicalTrials.gov (NCT05595369) and is complete.

Findings

Between July 27, 2023, and Sept 6, 2024, 1207 individuals were screened. Of these, 964 were randomly allocated and 959 participants, excluding four participants who were later found ineligible and one who did not initiate treatment, were enrolled in the three phenotypes: 332 to cognitive, 334 to autonomic, and 332 to exercise. In the 959 participants in the mITT population, 643 (67%) self-reported as female, 314 (33%) were male, and two participants had a sex of unknown or undifferentiated; 750 (78%) were White; and 108 (11%) were Hispanic, Latino, or Spanish. The median age was 49 years (IQR 38–59). No statistically significant benefits were observed for any phenotype for primary endpoints. For the cognitive phenotype, adjusted differences compared to placebo were 3·2% (95% CI –10·4 to 16·8, p=0·65) for the 25-day regimen and –2·2% (–15·5 to 11·1, p=0·74) for the 15-day regimen. For the autonomic phenotype, adjusted differences were –6·4% (–18·5 to 5·7, p=0·30) for the 25-day regimen compared to placebo and –0·1% (–12·5 to 12·3, p=0·99) for the 15-day regimen compared to placebo. For exercise, adjusted differences were –7·8% (–19·5 to 3·8, p=0·19) for the 25-day regimen compared to placebo and 0·9% (–11·4 to 13·2, p=0·88) for the 15-day regimen compared to placebo. There were no differences in secondary endpoints, and no safety signals were observed; there were no deaths, and 52 serious adverse events occurred in 42 (4%) of 963 participants over the course of the study.

Interpretation

Nirmatrelvir–ritonavir for 15 days or 25 days showed no evidence of benefit in long COVID in any of the three phenotypes studied. These findings suggest additional approaches to measuring the symptom burden and treating Long COVID are needed.

Funding

National Institutes of Health.

Source: 

Link: https://www.thelancet.com/journals/laninf/article/PIIS1473-3099(26)00406-8/fulltext

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#Bundibugyo at the #Border: The 2026 #Ebola #Outbreak and the Case for Pre-emptive #Countermeasure #Equity

 

Abstract

The 2026 Ebola outbreak caused by Bundibugyo ebolavirus in the Democratic Republic of the Congo and Uganda exposes a persistent structural flaw in global health security: preparedness remains overwhelmingly reactive and pathogen-specific. Despite the $518 million Africa CDC-WHO joint continental plan, no licensed BDBV vaccine or therapeutic is available; a 21-day (three-week) detection delay and cross-border transmission expose inadequate inter-epidemic investment in non-Zaire ebolavirus countermeasures. We argue for sustained, ring-fenced financing, institutionalised cross-border coordination, species-inclusive diagnostics, and real-time genomic data sharing to move African Ebola preparedness from reactive to pre-emptive.

Source: 

Link: https://www.sciencedirect.com/science/article/pii/S1477893926000682?via%3Dihub

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#Taiwan, Seasonal #Influenza and #COVID19 Epidemics Situation #Update (CDC, September 1 '26): #H1N1pdm09 flu virus and PQ.16.1.1 SARS-CoV variant are predominant

 

{Excerpt}

(...)

    The CDC pointed out that in the 34th week (August 23-29), there were 101,628 outpatient and emergency room visits for influenza-like illnesses, an increase of 5.6% compared to the previous week, showing a recent slow upward trend. 

    In addition, last week (August 25-31), there were 85 new cases of severe influenza complications (80 H1N1, 3 H3N2, and 2 untyped A cases) and 14 deaths (12 H1N1, 1 H3N2, and 1 untyped A case). 

    Laboratory monitoring data shows that the influenza virus currently circulating in the community is mainly type A, with type A H1N1 accounting for 74.1% of the cases. 

    This flu season (2023-2024) has seen a cumulative total of 1,224 severe cases (620 H1N1, 494 H3N2, 20 untyped type A, and 90 type B) and 234 deaths (113 H1N1, 102 H3N2, 7 untyped type A, and 12 type B). 

    The majority of severe cases are among those aged 65 and above (64.6%) and those with a history of chronic diseases (82.8%). 69.4% of those affected have not received the flu vaccine this season.

    According to data from the Taiwan Centers for Disease Control (CDC), the COVID-19 epidemic in Taiwan is declining, but it remains at a plateau. 

    In the 34th week (August 23-29), there were 21,969 outpatient and emergency room visits related to COVID-19, a 13.4% decrease compared to the previous week (August 16-22). 

    Last week (August 25-31), there were 69 new locally transmitted severe cases and 18 local deaths. 

    Since October 2025, there have been a cumulative total of 549 locally transmitted cases of COVID-19 complicated by severe illness, of which 91 have died. 

    The majority of severe cases are among those aged 65 and above (72.5%) and those with a history of chronic diseases (83.1%). 85.1% of these cases have not received the COVID-19 vaccine this season. 

    In the past four weeks, the predominant variant strain in locally transmitted cases has been PQ.16.1.1.

(...)

Source: 

Link: https://www.cdc.gov.tw/Bulletin/Detail/GWRkQ03fZuKKWwdv191UyQ?typeid=9

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#Antibody profiles across #H5N1 and previously circulating viruses are highly dynamic and #age- and imprint- independent

 

Abstract

The increasing incidence of H5N1 influenza virus transmission from animal species to humans has heightened concerns about an imminent H5N1 pandemic. Prior studies using recombinant hemagglutinin and neuraminidase proteins have reported age-dependent cross-reactivity to H5N1, attributed to immune imprinting from an individual's first influenza virus exposure. However, whether this pattern holds when using whole inactivated virus (WIV), capturing antibodies against diverse viral proteins, and is stable over time remains unknown. We therefore aimed to determine whether H5N1 cross-reactivity of pre-existing antibodies to whole virus follows an age-dependent or imprinting-specific pattern, and whether this pattern is stable over a five-year period. To this end, we measured serum antibody levels in adolescents, adults and seniors by ELISA using whole inactivated H5N1 virus as antigen rather than purified proteins. Detectable, albeit generally low, levels of H5N1-reactive antibodies were present in most individuals, irrespective of age. Comparison of antibody levels against H5N1 with those to five historical influenza virus strains revealed a consistent positive correlation between H5N1-reactive antibodies and responses to the H1N1pdm09 strain A/California/7/2009 (CA), across all age groups. Using unbiased clustering of antibody titers against H5N1, CA, and the H3N2 strain A/Perth/16/2009 (PE), we identified seven distinct age-transcending antibody profiles. These profiles covered individuals with varying titers to all three included viruses but also identified individuals with high anti-CA levels, yet low anti-H5N1 levels and vice versa. Moreover, despite stable antibody levels over a five-year interval in the study population, individual antibody levels and profiles fluctuated considerably over this period. Taken together, our results confirm the presence of H5N1-reactive antibodies in human sera and their association with previously circulating strains. However, they also caution against inferring antibody levels against a new strain based solely on responses to antigenically related strains and highlight the limitations of extrapolating immune status from single timepoint measurements.

Competing Interest Statement

The authors have declared no competing interest.

Source: 

Link: https://www.medrxiv.org/content/10.64898/2026.08.26.26361396v1

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Acute #Protein Responses Control #SARS-CoV-2-specific #Neurocognitive and General Post-Viral #Sequelae

 

Abstract

Post-acute infection syndromes (PAIS) follow viral syndromes including post-acute sequelae of COVID19 (PASC) which complicates 10-25% of SARS-CoV-2 infections. These syndromes lack precise explanatory mechanisms. We studied 173 human saliva proteomes during respiratory viral syndromes, seeking associations between 44 clinically-relevant protein expression patterns and subsequent sequelae counts. Exploratory models adjusted by extensive clinical annotations found interactions between 23 acutely-responsive proteins and SARS-CoV-2 infection that inversely predicted subsequent neurocognitive sequelae. An overlapping 19 acutely-responsive proteins during any acute respiratory viral syndrome inversely predicted general fatigue-related sequelae. Altogether, 29 proteins, derived from interferon stimulated genes (ISG), were uniformly beneficial, including 13 predictive of both neurocognitive and general sequelae. The proteins suggested both shared early pathobiology and virus-specific protective responses that shaped resolution of acute disease and different PAIS. Acutely elevated protective ISG proteins associated with reduced post-viral symptoms identify investigational starting points for novel mechanisms, diagnostics and therapeutics for PASC and PAIS.

Competing Interest Statement

Theodore G. Liou, Judy L Jensen and Kristyn A Packer received research funding from Anagram, Aridis, BioMX, Calithera, Clarametyx, Gilead, Insmed, Laurent, Novartis, the US Cystic Fibrosis Foundation′s Therapeutic Development Network and Vertex for performance of clinical studies during the study period. Bricelyn H Strauch maintains the copyright for Figure 3. Theodore Liou and Frederick Adler, through the University of Utah, are named as inventors on the following patent applications related to the proteins identified in this manuscript: (1) a provisional patent application titled ″DIAGNOSTICS AND TREATMENTS FOR ACUTE AND POST-VIRAL DISEASE BASED ON INNATE IMMUNE RESPONSES TO SARS-COV-2 INFECTION,″ serial number 63/792,687, filed 4/22/2025; (2) a provisional patent application titled ″ADDITIONAL INNATE IMMUNE RESPONSES WITH DIAGNOSTIC AND TREATMENT POTENTIAL FOR POST-ACUTE SEQUELAE OF COVID19 SYNDROME AND FOR POST-ACUTE INFECTION SYNDROME,″ serial number 63/979,883, filed 2/10/2026; (3) a Patent Cooperation Treaty (PCT) application titled ″METHODS FOR PREDICTING POST-ACUTE SEQUELAE OF VIRAL INFECTIONS USING INTERFERON STIMULATED GENE PROTEINS,″ serial number PCT/US2026/024520, filed 4/21/2026, which incorporates subject matter from (1) and (2); and (4) a provisional patent application titled ″ADDITIONAL ACUTELY EXPRESSED PROTEINS PROTECTIVE AGAINST NEUROCOGNITIVE AND GENERAL POST-VIRAL SEQUELAE,″ serial number 64/102,461, filed 6/30/2026. The applicant on all applications is the University of Utah.

Source: 

Link: https://www.medrxiv.org/content/10.64898/2026.08.27.26361488v1

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