HK CHP Reports 6 H9N2 Cases over the past 4 Reporting Periods

 

#19,409

As of today's report, Hong Kong's CHP has reported a total of 23 H9N2 cases over the past 6 months, with 6 of those reported by the CHP since October 19th.   As you can see by the dates in the above graphic, there continue to be substantial delays in reporting, with 5 of the 6 cases reported occuring in September. 

Four of the six cases are in children (who are more likely to be screened for the virus), while two are in elderly adults. 

While H9N2 infection is typically mild or moderate, some patients are hospitalized, and a few deaths have been reported.  The two most recent cases - announced today - were previously reported on in the WHO WPRO weekly avian flu report released on October 28th.

Human infection with avian influenza A(H9N2) virus

From 23 to 29 October 2026, two new cases of human infection with avian influenza A(H9N2) virus were reported to WHO in the Western Pacific Region, both from China. Both cases were paediatric patients, one from Liaoning Province, with symptom onset on 20 September 2026, and one from Guangxi Zhuang Autonomous Region, with symptom onset on 13 October 2026. Both cases had exposure to poultry. All close contacts of both cases tested negative for influenza A. Both cases had fully recovered at the time of reporting.

Since 2015, a total of 189 cases of human infection with avian influenza A(H9N2), including two deaths (both with underlying conditions), have been reported to WHO in the Western Pacific Region. Of these,186 were reported from China, two were from Cambodia, and one was from Viet Nam.

Most human infections with avian influenza A(H9N2) have been associated with exposure to infected poultry or contaminated poultry environments, and the majority of cases have been mild. Sporadic human infections continue to be expected in areas where H9N2 viruses circulate in poultry populations. Current evidence indicates that H9N2 viruses have not acquired the ability for sustained human-to-human transmission, and the risk of further community-level spread remains low.

Last August, in WHO Influenza at the human-animal interface (Aug 7th) - Uptick in H9N2 Cases in China, we looked at this recent increase in reported cases. Whether this is due to more frequent spillovers, or better surveillance, isn't known.

Despite being clearly zoonotic - LPAI H9N2 is considered a `non-reportable' disease in poultry or wild birds by WOAH (see Terrestrial Animal Code). Complicating matters, China's attempts to control LPAI H9N2 through vaccines have been less than successful.

Several recent Chinese studies have found signs that LPAI H9N2 is becoming better adapted to mammals, warning of its pandemic potential; including:

• In early August, in EM&I: Genetic evolution, phylodynamics, geographic spread of H9N2 avian influenza viruses in China from 2014 to 2025: an increasing potential zoonotic risk, we saw yet another Chinese study warning that H9N2 was accruing mammalian adaptations which increases its zoonotic risk.

• Five months ago, in Viruses: Epidemiological and Virological Characteristics of H9N2 Avian Influenza Virus in Jiangsu Province, China, 2024, researchers warned that that Jiangsu’s circulating H9N2 viruses have acquired human receptor preference and mammalian adaptation, posing silent infection and pandemic risks

• In October 2025, in China CDC Weekly: Epidemiological and Genetic Characterization of Three H9N2 Viruses Causing Human Infections, investigators reported a number of indicators of increased mammalian adaptation within the virus, including an enhanced ability to infect upper respiratory (α2,6-sialic acid) tract receptors, and a number of HA protein mutations, including; H191N, A198V, Q226L, and Q234L.

• The Asian Y280/G57 lineages have shown increasing signs of mammalian adaptation (see EM&I: Enhanced Replication of a Contemporary Avian Influenza A H9N2 Virus in Human Respiratory Organoids)), while the African and Middle Eastern Lineages (mostly European G1-like) are older and less evolved.

• In the summer of 2025, in Nature: Genetic diversity of H9N2 avian influenza viruses in poultry across China and implications for zoonotic transmission, researchers reported rising prevalence of key mutations associated with increased infectivity and pathogenicity in mammals.

While H9N2 doesn't garner the kind of headlines that H5N1 gets, our own CDC lists two lineages (A(H9N2) G1 and A(H9N2) Y280) as having at least some pandemic potential, and several candidate vaccines have been developed.

So we watch these developments with more than just academic interest. 

PNAS: Rare recovery of reassortants between contemporary clade 2.3.4.4b H5N1 viruses and human influenza A viruses in vitro

 

Coinfection leading to Antigenic `Shift' 

or Reassortment 

#19,408

Last week, in When Flu Viruses Collide, we looked at the concerns over rare - but documented - instances of seasonal flu reassorting with a novel flu virus, and producing a biologically `fit' hybrid.  

At least 2 pandemics in the last century (1957 and 1968) are believed the product of such an interaction. This is the reason why yearly flu vaccination has long been recommended for people who raise pigs or work with poultry and the CDC now urges vaccination in dairy workers.

In 2024, Chinese scientists looked at the reassortment potential of H5N1 and H3N2 (see Preprint: Intelligent Prediction & Biological Validation of the High Reassortment Potential of Avian H5N1 and Human H3N2 Influenza Viruses) and predicted the risks to be relatively high.

Another, older (2010) study (see PNAS: H3N2 And H5N1 Reassortment) found that Reassortment between avian H5N1 and human H3N2 influenza viruses creates hybrid viruses with substantial virulence.

While viewed as possible, it isn't clear how compatible contemporary seasonal viruses are for reassorting with currently circulating HPAI H5Nx viruses.

Complicating matters, since there is great diversity among all of these viruses - and they continually evolve - only partial answers are obtainable.

To that end, we have a brief report published yesterday in PNAS, which describes (partially successful) attempts to create reassortants using `weakened' (live attenuated NS1-truncated) clade 2.3.4.4b H5N1 HPAIVs of the B3.13 and D1.1 genotypes, and older (circa 2009 and 1968) human-adapted pdmH1N1 and H3N2 IAVs in MDCK II cells. 

Today's panoply of seasonal flu viruses have evolved considerably since those lineages emerged. But these are well characterized lab strains, with reverse genetic clones widely available, and their use likely makes comparisons with earlier studies easier. 

The authors acknowledge these (and other) limitations, but despite those constraints, they were able to generate 20 reassortants (0.74%). They report: 

Polymerase assays identified human IAV subunits, particularly H1N1 PA or H3N2 PB2, that increased H5N1 polymerase activity. Thus, contemporary clade 2.3.4.4b H5N1 viruses can reassort with human IAVs, but factors beyond polymerase compatibility may limit their recovery.

This study did not test these reassortants' fitness, transmissibility or disease severity, so it cannot predict real-world risk.  It does, however, suggest that contemporary clade 2.3.4.4b H5N1 viruses can reassort with human IAVs. 

Although it is not a particularly long report, I've only posted some excerpts. Follow the link to read it in its entirety. 

Rare recovery of reassortants between contemporary clade 2.3.4.4b H5N1 viruses and human influenza A viruses in vitro

Jakob Ankerhold, Susanne Kessler https://orcid.org/0000-0002-9720-8291, Philipp P. Petric, +4 , and Kevin Ciminski https://orcid.org/0000-0001-5397-7497 kevin.ciminski@uniklinik-freiburg.deAuthors Info & Affiliations

Edited by Peter M. Palese, Icahn School of Medicine at Mount Sinai, New York, NY; received September 8, 2026; accepted October 12, 2026 

November 9, 2026

123 (46) e2631654123

https://doi.org/10.1073/pnas.2631654123 

Abstract

Influenza A virus (IAV) pandemics can arise when animal-derived and human-adapted IAVs exchange genome segments; however, whether contemporary clade 2.3.4.4b H5N1 viruses can generate viable reassortants with human IAVs is unclear. Here, we tested the reassortment potential of two clade 2.3.4.4b H5N1 viruses with human-adapted H1N1 and H3N2 IAVs using a biosafe reassortment system. Across multiple coinfection conditions, we genotyped 2,698 plaque-purified viral clones and recovered 20 reassortants (0.74%). Polymerase assays identified human IAV subunits, particularly H1N1 PA or H3N2 PB2, that increased H5N1 polymerase activity. Thus, contemporary clade 2.3.4.4b H5N1 viruses can reassort with human IAVs, but factors beyond polymerase compatibility may limit their recovery.

 

Zoonotic influenza A viruses (IAVs) pose a constant pandemic threat, with previous pandemics often associated with reassortment between animal-derived and human-adapted IAVs (1). Reassortment requires coinfection of a cell and compatibility between viral genome segments from different host-adapted lineages (2). Highly pathogenic avian influenza viruses (HPAIVs) of the H5 clade 2.3.4.4b have created an unusually broad ecological interface for such events. Since 2020, these viruses have spread globally among wild birds and mammals and entered U.S. dairy cattle, resulting in human exposure and zoonotic infections (3–6). Although sustained human transmission has not been documented, cocirculation with seasonal human IAVs creates opportunities for coinfection and reassortment.

Previous studies showed that prepanzootic H5N1 HPAIVs can reassort with human IAVs (7–10). However, the reassortment potential of contemporary clade 2.3.4.4b H5N1 HPAIVs remains unknown. Here, we tested two clade 2.3.4.4b H5N1 HPAIVs, representing different viral genotypes associated with U.S. dairy cattle outbreaks (3, 5) in combination with human-adapted H1N1 and H3N2 IAVs. We show that contemporary clade 2.3.4.4b H5N1 viruses can form viable reassortants with human IAVs in vitro and identify distinct vRNP compatibility patterns.

(SNIP)

Discussion

In this study, we show that contemporary clade 2.3.4.4b H5N1 HPAIVs can reassort with human-adapted H1N1 and H3N2 IAVs, but reassortants represented only 0 to 2.3% of plaque-purified clones under the in vitro conditions tested. This finding is consistent with the absence of documented reassortment events involving human IAV segments in clade 2.3.4.4b H5N1 HPAIVs to date.

However, the low observed recovery frequency of reassortants does not indicate complete genetic incompatibility, as recovered reassortants carried human IAV polymerase segments and selected human IAV subunits increased H5N1 polymerase activity in human cells. Thus, our data separate reassortant recovery under the tested conditions from the functional properties of the resulting polymerase constellations.

As clade 2.3.4.4b H5 HPAIVs undergo frequent and complex reassortment with avian IAVs (4, 6), the factors potentially limiting reassortment with human-adapted IAVs remain unclear (2). Several limitations should be considered: MDCK II cells do not recapitulate natural infection dynamics or selective pressures, and the observed H5N1 replication advantage and viral progeny composition may differ in relevant hosts. Additionally, using NS1-truncated viruses and early pandemic representatives rather than contemporary seasonal isolates limits generalizability, while the absence of reassortant characterization limits conclusions about replication fitness, transmissibility, and pathogenicity.

Because no standardized benchmark for IAV reassortment exists, observed recovery frequencies cannot be directly compared across IAV combinations. Despite these limitations, our study provides a functional framework for interpreting reassortment risk during the ongoing clade 2.3.4.4b H5 panzootic.

       (Continue . . . )

 

Nature Sci Reports: The effect of the time of day of influenza vaccination on antibody and T-cell responses in older adults

Photo Credit - CDC PHIL

#19,407

Ten years and just over 8,000 blogs ago, in Vaccine: Taking Your Best Shot, we looked at a study published in the Journal Vaccine which suggested the time of day one is vaccinated may make a difference in the body's immune response.

The cluster-randomized trial followed 276 adults (over 65) across 24 GP practices in the West Midlands, UK who - between 2011 and 2013 - were assigned to receive their flu shots either in the morning or afternoon.

Follow up blood work showed higher antibodies against H1N1 and Influenza B (but not H3N2) in the morning vaccination cohort. (note: a follow-up Corrigendum - published several months later - weakened the evidence, finding that the influenza B result was no longer statistically significant).

Last week, a new study published in Nature Scientific Reports, revisits the idea and reports: 

Individuals vaccinated in the early morning (09:00) showed an approximately 32% stronger antibody response compared to individuals vaccinated in the afternoon (14:00)

That said, their results were mixed. Their main analysis found no statistically significant differences between vaccination periods, but a secondary analysis favored morning vaccination over early afternoon.

But curiously, not over late afternoon. 

Whether this effect actually results in improved vaccine protection hasn't been established, and the reasons behind the purported `afternoon trough' - assuming it is more than just a statistical variation - remains unclear. 

It is possible our internal body clocks may play a role. Some people (like myself) are early risers, so the same appointment time may fall at different points in our `biological day'.  

The researchers explored that possibility using patient's sleep schedules, but those results were inconclusive as well.  

Make of it what you will.  

I've posted the abstract and a snippet from the discussion. Follow the link to read the study in its entirety.

The effect of the time of day of influenza vaccination on antibody and T-cell responses in older adults 
 
Published: 05 November 2026
  
Download PDF 

Tamara M. J. Brouwers, Koen Vink, Martijn Vos, Harry van Dijken, Marijn E. Snik, Jan van de Kassteele, Lisa Beckers, Debbie Smit, Deborah Oomen, Teun Guichelaar, Tobias N. Bonten, Laura Kervezee, Jacco Wallinga & Debbie van Baarle

Abstract

Increasing evidence suggests that time of day of vaccine administration affects immune responses. We aimed to determine the optimal time of day for influenza vaccination by characterising temporal patterns in vaccine-induced immune responses. Additionally, we assessed the effect of vaccination time relative to an individual’s circadian phase on immune responses.

 A randomised controlled trial was conducted with 278 participants aged 60–85 years, who received influenza vaccination at a randomised time between 09:00 and 17:00. 

Antigen-specific antibody titers and T-cell responses to three vaccine strains (A/H1N1, A/H3N2 and B/Victoria) were measured pre- and one month post-vaccination. A permutation-based test was used to determine differences in strain-specific immune responses between the three randomisation time blocks (09:00–11:40, 11:40–14:20, 14:20–17:00). 

As a secondary analysis, strain-specific immune responses were jointly analysed in a single generalised additive mixed-effects model (GAMM) to assess the overall impact of influenza vaccination timing. The permutation-based test found no significant differences in immune responses between the three vaccination time blocks. A GAMM revealed that morning vaccination resulted in significantly higher antibody responses across strains than early afternoon vaccination(p = 0.045), but not late afternoon vaccination (p = 0.498). 

Antibody responses displayed a non-significant non-linear pattern from 09:00 to 17:00, with the model suggesting highest responses in participants vaccinated at 09:00. A similar trend was observed for T-cell responses.

Irrespective of chronotype, vaccinations administered at the start of an individual’s day tended to elicit the strongest vaccine-induced immune responses. Although statistical evidence for a time-of-day effect was limited, numerically higher antibody and T-cell responses were consistently observed in the morning group.

        (SNIP)

Discussion 

This study showed a consistent trend toward stronger strain-specific antibody and T-cell responses among older adults vaccinated in the morning compared to those vaccinated in the afternoon. However, the differences between vaccination time groups did not reach statistical significance in our primary analysis. After adjustment for variation in baseline antibody titers using GAMM analyses, overall antibody responses differed significantly between the morning and early afternoon vaccination groups, but not between the morning and late afternoon vaccination groups. An important strength of the study is its assessment of temporal patterns in vaccine-induced immune responses across a continuous vaccination window from 09:00 to 17:00. A trend was observed toward stronger vaccine-induced immune responses following vaccination in the early morning (at 09:00).

       (SNIP)

In conclusion, we consistently showed that morning influenza vaccination tended to result in stronger vaccine induced immune responses than (early) afternoon vaccination in adults aged 60–85 years. Our results contribute to the growing evidence on the effect of vaccination timing on vaccine-induced immune responses and suggest potential clinical relevance in older adults. Optimising the timing of vaccine administration may therefore offer a safe and cost-effective strategy to enhance immunogenicity of current influenza vaccines, although further investigation into clinical outcomes is warranted. 

       (Continue . . . )  

IJID Review Article: The H5N1 avian influenza threat: a European Perspective on Research Gaps and State of Preparedness

 

#19,406

While the next pandemic could arise from a wide variety of sources (see WHO 2024 Pathogens Prioritization Report), the most obvious contender today is HPAI H5Nx, which continues to expand its host range as it spreads around the globe. 

Despite the near-inevitability of another pandemic crisis, the world remains slow to embrace that stark reality, and prepare seriously. 

Three years after the start of the last pandemic, in 2023's Lancet Preprint: National Surveillance for Novel Diseases - A Systematic Analysis of 195 Countries, the authors found that the self-reported 66% readiness score for detecting and dealing with novel viruses was not supported by the available evidence.  They wrote:

`A minority of countries have public evidence of novel disease consideration, and significant geographical heterogeneity exists in where this is located.'

Today, most surveillance is passive, and much of what is detected, isn't readily shared. There are often long delays in submitting viral sequences (see Nature: Lengthy Delays in H5N1 Genome Submissions to GISAID) - averaging 7 months - but sometimes taking 1 to 2 years. 

We've also seen repeated warnings from public health agencies that our surveillance systems are not designed to detect novel viruses. 

In 2024 the ECDC issued guidance for member nations on Enhanced Influenza Surveillance to Detect Avian Influenza Virus Infections in the EU/EEA During the Inter-Seasonal Period., which cautioned:

Sentinel surveillance systems are important for the monitoring of respiratory viruses in the EU/EEA, but these systems are not designed and are not sufficiently sensitive to identify a newly emerging virus such as avian influenza in the general population early enough for the purpose of implementing control measures in a timely way.

Similarly, in 2023's analysis from the UKHSA (see TTD (Time to Detect): Revisited), they estimated there could be dozens or even hundreds of undetected human H5N1 infections before public health surveillance would likely detect them, potentially over a period of weeks or months. 

While we've seen a steady chorus of voices from the scientific community calling for more aggressive surveillance and testing (see here, here, here, here, and here) - the world seems content to don blinders and hope for the best.

Today we've a review article in the International Journal of Infectious Diseases (IJID) that examines the current H5N1 threat, and Europe's readiness to deal with it. 

While they cite progress, they urge that Europe strengthen preparedness now, because an emerging human outbreak would likely far outpace our ability to manufacture and deploy vaccines. 

I've only posted some brief excerpts, so follow the link to read the review in its entirety.  I'll have a brief excerpt after the break.

The H5N1 avian influenza threat: a European Perspective on Research Gaps and State of Preparedness

Lone Simonsen 1, Tyra Grove Krause 2 3, Anders Gorm Pedersen 4, Lars E Larsen 5, Marlies Jilles Francine Goedknegt 1, Ramona Trebbien 2, Olav Hungnes 6, Preben Aavitsland 6, Otto Helve 7, Richard J. Webby 8, Marc-Alain Widdowson 9, Bolette Søborg 2, Marion Koopmans 10 11 12, Eskild Petersen 1

10.1016/j.ijid.2026.109220 

Highlights

•  Surveillance must strengthen One Health with closer collaboration between human and veterinary public health.

• Functional assays measuring H5N1 binding to α2,3- or α2,6 sialic acid will help.

• Detect early receptor switching.

• Novel vaccine platforms like the mRNA and Adenovirus must be developed to seasonal influenza to be available for rapid manufacture in a pandemic situation.

Abstract

H5N1 influenza clade 2.3.4.4b has spread from South East Asia through migratory birds since 2020. The expansion seeded frequent spillovers into wild and domestic mammals including cattle in the United States. While the risk for humans not in direct contact with infected animals is low, the widespread presence and opportunities for evolution constitutes a pandemic threat.

If sustained human-to-human transmission (H2H) would emerge, there is limited time to mount a public health response. Initially, non-pharmaceutical interventions (NPIs) are needed until vaccines are available. Experience with H5N1 viruses since 1997 suggests that infections are seen mostly in people born after 1968, indicating that people under sixty may be at particular risk.

Closely monitoring viral diversity and evolution in wild life, and at the human animal interface, using integrated One Health surveillance and genome-based selection of viruses for further characterization for instance receptor affinity of H5N1 to human receptors is mandatory.

        (SNIP)

An influenza A pandemic in our lifetime is highly likely, given there were four in the last 100 years. However, the severity of a future influenza pandemic remains uncertain - it could be as devastating as 1918 or as mild as 2009.[73]

A robust European strategy must be developed during “peace time”, with sustained investment in diagnostics, surveillance, and flexible vaccine manufacturing. Additionally, it is crucial to anticipate, address and counter anti-science and anti-vaccine sentiments, which posed significant challenges during COVID-19. Effective mitigation and vaccination efforts depend on public trust in health authorities.

Although this review focused on the H5N1 threat, the next pandemic could be caused by another influenza A subtype, a coronavirus, or an entirely different pathogen. Given this uncertainty, preparedness efforts should prioritize surveillance anticipating a broad range of pathogens.

       (Continue . . . ) 


While it remains to be seen how the world responds to growing calls for pandemic preparedness (see UN High-Level Meeting on Pandemic Prevention, Preparedness and Response (PPPR)), there are things you can do as an individual to reduce your risk from a pandemic.

As we discussed in  #Natlprep 2025: Personal Pandemic Preparedness, buried in the CDC's archives are a number of useful documents for individuals, schools, and employers on dealing with a pandemic.:

• Get Your Household Ready For Pandemic Flu {PDF - 16 pages]
• Get Ready for Pandemic Flu: Educational Settings [PDF – 16 pages]
• Get Ready for Pandemic Flu: Workplace Settings [PDF – 16 pages]  

I also recommend getting (and being) a Flu Buddy, availing yourself of the vaccines that are available now (Flu/COVID/RSV, Pneumonia, etc.), stockpiling OTC meds and PPE, and being prepared to shelter in place. 

Even if a pandemic doesn't come in the near future, these are all things that would benefit you and your family during any prolonged emergency. 

And those, sadly, appear to be increasingly common.  For more on that, you may wish to revisit:

The UK's `Be Ready' Preparedness Campaign

September Is National Preparedness Month (#NPM26)

#Natlprep 2026: Pandemic Planning At Both Ends of the Spectrum

UK National Risk Register 2026 - Urges Citizen Preparedness

Washington State Adds 3 More H5N1 Infected Herds - HPAI North American Roundup

 

#19,405

Since last Monday, Washington State has reported 3 more infected dairy herds (2 in Yakima County, 1 in Benton), bringing to 43 the number of herds reported since the first week of October.

The number of human infections remains at 3 (1 fatal), with the CDC posting the following brief description in yesterday's FluView. 

Novel Influenza A Virus Infections

Two confirmed human infections with avian influenza A(H5) virus were reported to CDC this week, including one death. To date, human-to-human transmission of avian influenza A(H5) virus has not been identified in the United States.

Both cases were reported by the Washington State Department of Health and occurred in adults aged ≥18 years who worked at commercial dairy cattle farms where highly pathogenic avian influenza (HPAI) A(H5N1) virus has been detected in cows.

One individual developed respiratory symptoms during the week ending October 24, 2026 (Week 42). The patient presented to an emergency department the following week, was hospitalized, and has died. A respiratory specimen collected at the healthcare facility tested positive for influenza A and was presumptive positive for influenza A(H5) at the University of Washington. The specimen was sent to the Washington State Public Health Laboratory where influenza A(H5) was confirmed using the CDC influenza A(H5) assay. Additional testing conducted by the University of Washington determined this was an avian influenza A(H5N1) virus.

The second individual developed conjunctivitis and sought healthcare. Specimens were collected from the individual and tested at the state public health laboratory using the CDC influenza A(H5) assay during the week ending October 31, 2026 (Week 43). Influenza A(H5) virus was confirmed by the state public health laboratory. The specimen has been shipped to CDC for additional testing.

There has been a total of three influenza A(H5) cases in dairy workers in Washington.

The USDA continues to report a sharp uptick in backyard and commercial poultry outbreaks of HPAI H5 across the nation, with 18 states reporting spillovers. California is currently hardest hit, with > 1,300,000 birds affected.

Canada has reported 27 outbreaks since bird flu activity resumed in mid-September, with 6 reports filed over the past week.

And lastly, Mexico's Senasica is reporting a large outbreak of H5N1 in Yucatán. While Mexico has reported H5N1 in wild birds recently, this appears to be the first poultry outbreak since 2024.

        (Translation)

Agriculture promptly addresses avian influenza case in Yucatán

Senasica is conducting a diagnostic assessment to determine if there are more affected farms and will analyze the appropriateness of authorizing emergency vaccination.

National Service for Agrifood Health, Safety and Quality | November 5, 2026 | Press Release

The Ministry of Agriculture emphasizes that the consumption of eggs and chicken is completely safe and that there is no risk to the national poultry industry.

In a timely response of less than 24 hours, the Ministry of Agriculture and Rural Development (Agriculture) confirmed and activated international health protocols for the control of a case of highly pathogenic avian influenza (HPAI) AH5N1, detected in a commercial Poultry Production Unit (UPA) for table eggs in Umán, Yucatán.

The affected farm had a population of 225,860 laying hens, a figure that represents only 0.09 percent of the national inventory, so the event does not impact the supply in the market.

The Ministry of Agriculture reiterates to the public that this case does not pose a risk to the national poultry industry. The supply of poultry products nationwide is fully guaranteed, and the consumption of poultry meat and eggs is completely safe.

Upon receiving notification of the unusual mortality of 862 birds from the farm's veterinarian, official personnel from the National Service for Agrifood Health, Safety and Quality (Senasica) immediately went to the site. Following strict biosecurity protocols, samples were taken and tested positive for HPAI subtype H5 at the Official Biosafety Level 2 Laboratory in Mérida.

Subsequently, the samples were transferred to the Biosafety Level 3 Laboratory of the Mexico-United States Commission for the Prevention of Foot-and-Mouth Disease and Other Exotic Animal Diseases (CPA) in Palo Alto, Mexico City, for further virus isolation and sequencing tests.

Therefore, he stated that specialists from CPA-Senasica delimited a risk area of ​​10 kilometers in radius and immediately implemented international counter-epidemic measures:

• A definitive quarantine was applied to the UPA and the total depopulation of the farm was carried out, sanitary disposal of the birds, destruction of waste and contaminated materials, as well as the cleaning and disinfection of the facilities.
• After the sanitary break period is completed, sentinel birds will be introduced to verify the absence of the virus before authorizing restocking.
• CPA technicians deploy sampling in all fattening, commercial egg-laying and breeding UPAs located within the risk perimeter. 

The diagnosis will determine if there are more affected farms and, according to the results, the General Directorate of Animal Health of Senasica will analyze the appropriateness of authorizing emergency vaccination of the birds that are in the farms surrounding the detected case.

As part of the origin analysis, authorities also inspect nearby bodies of water, where migratory wild birds from the north of the continent usually arrive during the winter season.

In addition, he reported that an expert group in wildlife epidemiological surveillance will soon arrive to intentionally and systematically search for cases of the disease in free-living birds and thereby confirm whether the source of infection is associated with infected migratory species.

During the winter season, the Ministry of Agriculture intensifies epidemiological surveillance throughout the country and invites producers to reinforce biosecurity measures on their farms and to report any suspicion immediately through the Senasica service channels: telephone line 800 751 2100, WhatsApp 55 3996 4462 and email gestioncpa.dgsa@senasica.gob.mx .

South Korea: MAFRA Reports 2 Outbreaks of HPAI H5N9 in Poultry & Ducks

 

#19,404

Over the 2024-2026 flu season, South Korea's MAFRA Reported Increased Infectivity & Pathogenicity of last Year's Avian Flu Strains, which - for the first time - included 3 HPAI subtypes (H5N1, H5N6, and H5N9).

Notably, their Animal and Plant Quarantine Agency also reported H5N1's infectivity was more than 10 times higher than in previous years. 

 

Last year MAFRA reported 62 outbreaks in poultry, and 63 detections in wild birds. While details were scant at the time, last September a highly technical report published in Virus Research added considerable detail. Briefly it reported:

• Last year South Korea was visited by a diverse panoply of H5Nx genotypes (n=16), with at least two - H5N9 N9-G2 and H5N1 25G2 - displaying unusually high infectivity in chickens.

• H5N1 25G2 was also deadly to ducks, whereas H5N9 N9-G2 spread efficiently in ducks, albeit without producing serious illness.

• H5N1 25G2 was the source of nearly half (n=30) of last year's 62 South Korean poultry outbreaks, but it was only detected in environmental samples once, making its prevalence in wild birds unknown.

This year's avian flu season has already started in South Korea, with a report of H5N1 In wild leopard cat in Seosan, South Chungcheong Province less than a week ago, and - over the past 4 days - 2 seperate outbreaks of H5N9. 

The first, reported on Nov 4th, is from the north of the country near the DMZ, while the second is in the far south of the country.  

        (translated)

Nationwide disease control measures strengthened following the first outbreak of highly pathogenic avian influenza (AI) at a laying hen farm in Yeoncheon, Gyeonggi Province.

2026.11.04 18:00:00 Quarantine Policy Bureau Avian Influenza Prevention Division

The Central Disaster Management Headquarters for Highly Pathogenic Avian Influenza ( headed by Minister of Agriculture, Food and Rural Affairs Song Mi-ryeong , hereinafter the Headquarters ) announced on Wednesday , November 4 , that highly pathogenic avian influenza (H5N9 type ) was confirmed at a laying hen farm ( approximately 91,000 birds ) located in Yeoncheon-gun, Gyeonggi-do .

Accordingly, it was announced that on November 4 ( Wed ), a meeting of the Central Disaster and Safety Countermeasure Headquarters, presided over by Director General of Food Policy Park Jeong-hun and attended by relevant agencies and local governments, would be held to review the outbreak situation of highly pathogenic avian influenza and quarantine measures, and to strengthen quarantine management .

1. Situation of Occurrence

The owner of a laying hen farm in Yeoncheon, Gyeonggi Province, reported an increase in chicken deaths to the Northern Gyeonggi Animal Health Laboratory, and as a result of a detailed examination , it was confirmed on November 4 ( Wed ) as highly pathogenic avian influenza (H5N9 type ) . This outbreak is the first case at a domestic poultry farm in the '26/'27 season .

Considering the recent continued detection of highly pathogenic avian influenza in wild birds and the high incidence of outbreaks in laying hen farms last season, thorough disease control management, such as adherence to biosecurity protocols and strengthened disinfection, is required at poultry farms nationwide .

Of the 62 cases that occurred in the '25/'26 season, 31 were at laying hen farms ( 17 were at large laying hen farms with over 100,000 birds ).

In particular , it is a serious situation requiring intensive management, such as disinfection , surveillance , and inspection, centered on large-scale laying hen farms and densely populated areas that suffer significant damage in the event of a highly pathogenic AI outbreak .

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Quarantine management strengthened following the confirmation of highly pathogenic avian influenza at a broiler duck farm in Jangheung, Gwangju, Jeonnam.

2026.11.06 18:50:00 Quarantine Policy Bureau Avian Influenza Prevention Division

The Central Disaster Management Headquarters for Highly Pathogenic Avian Influenza ( headed by Minister of Agriculture , Food and Rural Affairs Song Mi-ryeong , hereinafter the Headquarters ) announced on November 6 (Fri) that highly pathogenic avian influenza (H5N9 type) was confirmed at a broiler duck farm ( approximately 22,000 ducks) located in Jangheung , Gwangju , South Jeolla Province .

Accordingly, it was announced that on November 6 ( Fri ), a meeting of the Central Disaster and Safety Countermeasure Headquarters was held under the chairmanship of Director of the Disease Control Policy Bureau Lee Dong-sik, with the participation of relevant agencies and local governments , to review the situation regarding the outbreak of highly pathogenic avian influenza and disease control measures, and to strengthen disease control management .

1. Situation of Occurrence

At a broiler duck farm in Jangheung, Gwangju, Jeollanam-do, the farm owner reported an increase in mortality to Jangheung-gun , and as a result of a detailed inspection , it was confirmed on November 6 ( Fri ) as highly pathogenic avian influenza (H5N9 type ) . Including this outbreak, two cases of highly pathogenic avian influenza have occurred at domestic poultry farms during the winter of '26/'27 .

* Status of outbreaks at poultry farms this winter ('26.11.3.~): 1 case ( Laying hens in Yeoncheon, Gyeonggi-do )

With additional outbreaks occurring just two days after the first outbreak at a poultry farm on November 3 , and the risk of further outbreaks being very high in farms with inadequate quarantine measures , all poultry farms nationwide need to strengthen biosecurity and report any suspected symptoms to the quarantine authorities without delay .

In particular , as the first outbreak of the season has been confirmed at a duck farm, thorough disease control management is required for duck farms under the jurisdiction of affiliates .

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While two outbreaks does not a flu season make, for South Korea to kick off their avian flu season with back-to-back H5N9 outbreaks (hundreds of miles apart) is worthy of mention.

Last year, H5N9 made up just 5 of 62 (8%) of South Korea's poultry outbreaks and 10% of wild bird (environmental) samples.  It will be of great interest to see if H5N9 continues to spread.

Also worth mentioning, last year H5N9 was described as highly lethal in chickens, but without producing serious illness in ducks. Friday's announcement cites `an increase in mortality' on the affected duck farm.

Of course, the H5N9 subtype returning this fall could be a different genotype than was seen last year.   

As we discussed as recently as yesterday (see EM&I: Emergence of a Distinct Evolutionary Cluster of Clade 2.3.4.4b H5 Viruses in China during 2024-2025 with Rapid Evolution and Antigenic Divergence), HPAI is constantly reinventing itself.

In addition to H5N9 in South Korea, H5N5 is making moves (see HPAI H5N5: A Variation On A Theme) in high latitude regions of the Northern Hemisphere, and H5N6 continues to simmer in China. 

Although it seems unlikely that today's H5N1 juggernaut could be toppled by any of these competing subtypes, it wasn't all that long ago (2020) that H5N8 was the dominant subtype.

A reminder that HPAI is highly unpredictable, and its threat can change over time.