Abstract Title
Age-related variation in avian influenza A(H5N1), A(H5N6), A(H7N9), and A(H9N2) risk in humans: A potential role for neuraminidase
Abstract
Background: Gostic et al (2016) explained the younger age of avian influenza A(H5N1) (group 1[Gp1]) vs. A(H7N9) (group 2[Gp2]) human-zoonotic cases on the basis of group-specific hemagglutinin-stalk (HA2) imprinting and cross-protection, induced by human-adapted influenza A viruses circulating before (Gp1: H1N1 from 1918; H2N2 from 1957) vs. after (predominantly Gp2: H3N2) the 1968 pandemic. Here we explore further, interpreting within a framework of potential group-specific anti-HA2, but also homosubtypic anti-neuraminidase (NA), cross-protection.
Methods: We assembled line-lists of laboratory-confirmed Gp1-H5N1 (2003-2024: n=932), Gp1-H5N6 (2014-2024: n=94), Gp1-H9N2 (2003-2024: n=126), and Gp2-H7N9 (2013-2019: n=1568) human-zoonotic cases globally, comparing age and birth-year distributions.
Results: Relative to WHO tallies, our line-lists are complete for age (years) for >95% cases, youngest (median; IQR) for H9N2 (4; 2-8) and H5N1 (18; 5-31), substantially older for H5N6 (50; 33.5-55.75) and H7N9 (57; 45-67). Fewer Gp1-H5N1 than Gp2-H7N9 cases were born pre-1968 (~10% vs. ~70%), consistent with group-specific anti-HA2 cross-protection, as per Gostic et al. Despite shared H5, fewer H5N1 than H5N6 cases were born pre-1957 (~5% vs. ~15%), suggesting potential added role of homosubtypic anti-N1 cross-protection in older adults. Like Gp1-H5N1, ~90% of Gp1-H9N2 cases were born post-1968; however, fewer H9N2 than H5N1 cases were born 1968-2008 (~15% vs. ~80%) than since 2009 H1N1 resurgence (~80% vs. ~15%), suggesting potential role for anti-N2 cross-protection. Patterns were similar restricting to cases since 2014.
Conclusions: Surveillance data suggest group-specific anti-HA2 and homosubtypic anti-NA immunity may modulate the age-related risk of zoonotic influenza, critical to pandemic preparedness and warranting further investigation.
Methods: We assembled line-lists of laboratory-confirmed Gp1-H5N1 (2003-2024: n=932), Gp1-H5N6 (2014-2024: n=94), Gp1-H9N2 (2003-2024: n=126), and Gp2-H7N9 (2013-2019: n=1568) human-zoonotic cases globally, comparing age and birth-year distributions.
Results: Relative to WHO tallies, our line-lists are complete for age (years) for >95% cases, youngest (median; IQR) for H9N2 (4; 2-8) and H5N1 (18; 5-31), substantially older for H5N6 (50; 33.5-55.75) and H7N9 (57; 45-67). Fewer Gp1-H5N1 than Gp2-H7N9 cases were born pre-1968 (~10% vs. ~70%), consistent with group-specific anti-HA2 cross-protection, as per Gostic et al. Despite shared H5, fewer H5N1 than H5N6 cases were born pre-1957 (~5% vs. ~15%), suggesting potential added role of homosubtypic anti-N1 cross-protection in older adults. Like Gp1-H5N1, ~90% of Gp1-H9N2 cases were born post-1968; however, fewer H9N2 than H5N1 cases were born 1968-2008 (~15% vs. ~80%) than since 2009 H1N1 resurgence (~80% vs. ~15%), suggesting potential role for anti-N2 cross-protection. Patterns were similar restricting to cases since 2014.
Conclusions: Surveillance data suggest group-specific anti-HA2 and homosubtypic anti-NA immunity may modulate the age-related risk of zoonotic influenza, critical to pandemic preparedness and warranting further investigation.
Co-Author(s)
Lea Separovic, Immunization Programs and Vaccine Preventable Diseases Service, BC Centre for Disease Control, Vancouver BC;
Samantha Kaweski, Immunization Programs and Vaccine Preventable Diseases Service, BC Centre for Disease Control, Vancouver BC;
Gabriel Canizares, Immunization Programs and Vaccine Preventable Diseases Service, BC Centre for Disease Control, Vancouver BC;
Yuping Zhan, Immunization Programs and Vaccine Preventable Diseases Service, BC Centre for Disease Control, Vancouver BC;
Suzana Sabaiduc, Public Health Laboratory, BC Centre for Disease Control, Vancouver BC;
Gaston De Serres, Université Laval, Quebec City QC;
Danuta M Skowronski, Immunization Programs and Vaccine Preventable Diseases Service, BC Centre for Disease Control, Vancouver BC, and School of Population and Public Health, University of British Columbia, Vancouver BC
Abstract Category
Avian influenza in mammals, pandemic preparedness, and one health