H5N1 Exposure and Immunity in Canadian Hutterites: A Key Sentinel Population

Highly pathogenic avian influenza (HPAI) H5N1 viruses were first detected in 1996 and have caused sporadic outbreaks since that time, including hundreds of human infections. Unlike seasonal influenza whose death rate is well under 1 % for healthy adults, HPAI H5N1 infections have had a reported cumulative death rate of over 50 %. Beginning in 2018, a new family of H5 HPAI viruses began circulating globally and in 2022, this outbreak of H5N1 had reached North America resulting in an unprecedented number of deaths of wild birds and mammals, and millions of culled poultry. In early March of 2024, reports of H5N1 infections in US dairy cattle raised the concern that this virus might cause more widespread infections in humans, potentially leading to a pandemic. Hutterite communities in the Canadian Prairies subsist primarily on farming and as a result, are at high risk of exposure to HPAI H5N1. We have been conducing studies with Canadian Hutterite communities for over 15 years and have been conducting an ongoing study since 2020. Using samples collected during this study, we will determine whether these communities may have already been exposed to HPAI H5N1 - which provides critical information needed to inform risk assessments of farming communities nationally. We will also test the underlying immune responses that may provide cross-protection against HPAI H5N1 infection in individuals from across the age spectrum in order to understand which age groups are at highest risk of infection. Together, this will address several urgent and important knowledge gaps needed to inform public health policy to prevent spillover of HPAI H5N1 into humans.