Public Health Agency of Canada Expert Panel on Avian Influenza A(H5Nx) in Canada: Meetings

Opening Remarks

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The Chief Public Health Officer (CPHO) of PHAC, Dr. Theresa Tam, provided opening remarks for the meeting. Dr. Tam acknowledged the value of bringing together intra- and extra-mural One Health expertise on this priority public health topic and noted the importance of input from panelists in informing decision-making for the current A(H5N1) outbreak across the Health Portfolio.

This meeting will focus on virological and phylogenetic evolution and how these fields can best inform risk assessments for Influenza A(H5N1).

Agenda overview and administrative updates

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Panelists were provided with a draft Summary of Discussion (SoD) from Meeting 3 (May 3, 2024) and invited to provide feedback via written follow up. Following panel members' review, the SoD will be considered approved and will be posted on Canada.ca.

Participants were invited to raise additional declarations of affiliations and interest with respect to the meeting’s agenda items. None were raised.

Situational Update on A(H5N1)

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The Deputy Chief Veterinary Officer of the Canadian Food Inspection Agency (CFIA), and Director General of the PHAC Centre for Foodborne, Environmental and Zoonotic Infectious Diseases, provided an overview of the current situation for avian influenza from animal and human health perspectives, respectively.

Canada continues to monitor the outbreak of avian influenza in US dairy cattle which is now associated with two human cases. To date there have been no human or bovine cases of influenza A (H5N1) reported in Canada, and recent CFIA testing has not detected any viral fragments in sampled retail milk products.

PHAC continues to take a proactive approach to preparedness - planning for enhanced human surveillance activities, extending integrated surveillance efforts beyond the seasonal influenza season, updating guidance and public communications, and engaging with the Canadian Centre for Occupational Health and Safety regarding the development of guidance and risk communications for workplaces with animal and animal product exposures.

Key Issue: H5N1 High pathogenicity avian influenza: The journey from birds to mammals

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A US expert in highly pathogenic avian influenza, Dr. David Swayne, delivered a presentation on the viral evolution and recent emergence of avian influenza clade 2.3.4.4b in the Americas followed by detection of transmission among US dairy herds. Discussions highlighted the value of genomic tools for characterizing the virus and understanding the evolving routes of transmission, as well as the need for vigilance and active monitoring of animal populations to ensure early identification of potential infection and inform response efforts.

Key Issue: Spillover and emergence of H5N1 in US dairy cattle

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Virologist and researcher from the Vaccine and Infectious Disease Organization (VIDO) at the University of Saskatchewan, Dr. Angela Rasmussen, delivered a presentation on the spillover and emergence of influenza A (H5N1) in US dairy cattle, highlighting recent phylogenetic studies and genomic computational epidemiology. Findings suggest that the transmission of influenza A(H5N1) in US cattle is the result of a single spillover event with subsequent transmission, but studies have been unable to determine as of yet the functional impacts of virological mutations on mammalian adaptation. The presenter noted that important gaps remain in the available sequence data, and that there is a need for increased availability and accessibility of sequences together with accurate metadata from influenza A(H5N1) testing to better understand the scale and scope of the current animal outbreak.

Collaborative Science Spotlight: Risk assessment virological studies with influenza A(H5N1) viruses detected in various species in Canada

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A researcher with the PHAC National Microbiology Laboratory presented on recent research conducted in collaboration with the CFIA National Centre for Foreign Animal Diseases that aimed to explore the transmission routes and adaptation of avian influenza to mammals. In vivo studies assessed avian influenza viruses circulating in Canada for virulence and transmission in mice and ferret models. Findings were previously released in a 2023 preprint, and highlighted the varied ability of these viruses to productively replicate in mammalian cells and to cause disease in mammalian animal species. Additional research is required to better understand the impacts of evolving viruses in diverse animal populations, and in hopes of identifying genetic mutations that increase the risk of transmissibility and severity. Resulting discussion flagged that more information is needed to understand the respective roles of innate and adaptive immune responses. Expert panel members suggested there is a need for the development of anti-N1 assays so as not to overlook the potential effects of neuraminidase given high homology between the humanized N1 antigens and those of the currently circulating H5N1 strains.

Roundtable discussion:

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Panel members and participants engaged in discussions on the implications of virological evolution, and the ability of the circulating strain to spillover to unique animal populations, via various routes of transmission, and resulting in diverse presentations of symptoms/disease. Surveillance and genomic analyses provide valuable and necessary tools to help monitor the spread, inform risk scenarios and preparedness activities, and mitigate the impacts of disease on wildlife, agricultural animals, and humans.

Conclusions and next steps

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PHAC’s CSO and CPHO provided concluding remarks, acknowledging the evolution of enhanced surveillance and purposeful interplay of animal/human surveillance activities, the outstanding knowledge gaps, and the need for strategic coordination and focusing of available resources where they will be most impactful.

Opening Remarks

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The Chief Public Health Officer (CPHO) of PHAC, Dr. Theresa Tam, provided opening remarks and reflections on the evolving context of avian influenza A(H5Nx) in Canada and globally. Dr. Tam acknowledged the interdisciplinary scientific expertise within the panel, which included representation across animal and human health, specifically noting the importance of the panel in helping to identify research priorities and build improved pandemic preparedness approaches using a One Health approach. Research priorities informed through previous engagement are to be published on Canada.ca  in Spring 2024.

Agenda overview and administrative updates

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Participants were reminded that panel discussions operate under Chatham house rules. The summary of discussion from meeting #2 was distributed secretarially following the previous meeting.

Panelists were invited to raise additional declarations of affiliations and interest with respect to the meetings' agenda items. No additional declarations were raised.

Situational Update on A(H5N1)

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Spillover and transmission of avian influenza A(H5N1) clade 2.2.4.4b in lactating dairy cattle in the United States of America was reported in March 2024. PHAC Vice President of the Infectious Disease and Vaccination Programs Branch, and the Canadian Food Inspection Agency (CFIA) Chief Veterinary Officer provided an overview of the current situation for avian influenza A(H5Nx) from a human public health and animal health perspective, respectively.

PHAC is taking a proactive approach to preparedness through updated risk assessment, monitoring and surveillance, updating guidance and leveraging existing vaccine and therapeutic plans and measures.

CFIA has implemented additional importation measures, expanded animal testing for H5N1, and promotion of enhanced biosecurity on farms.

Key Issue: Surveillance in poultry for avian influenza

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Key Issue: UKHSA Avian influenza enhanced surveillance study

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The lead principal investigator for the United Kingdom Health Security Agency’s (UKHSA) Asymptomatic Avian Influenza Surveillance Study (AAISS) pilot attended as a guest speaker providing an overview and reflections of the study design, implementation, and study results.

Considerations for conducting a similar study in Canada were discussed, including for protocol design to encompass multi-animal zoonotic influenza, considerations for the socially complex contexts, and community engagement in the study design and implementation.

Opportunities for enhanced surveillance in Canada

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Following the presentations, panel members engaged in discussions identifying opportunities and considerations for active, or enhanced surveillance study approaches for avian influenza in Canada integrating surveillance at animal-human interface.

Discussions noted the importance of taking a One Health approach; complementing routine and enhanced surveillance with integrated reporting and interpretation across animal and health dimensions; exploring use of multiple methods for avian influenza A(H5Nx) surveillance and research (e.g., genomics, PCR testing, modelling, wastewater, serology); and the need for a framework for preparedness scenarios and triggers for action which bring together animal and human health dimensions with a focus on prevention interventions over response activities. Equity considerations and community engagement were also raised as critical dimensions to consider.

Conclusions and next steps

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