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ARS Home » Midwest Area » Ames, Iowa » National Animal Disease Center » Virus and Prion Research » Research » Publications at this Location » Publication #430566
Research Project: Intervention Strategies to Control Endemic and New and Emerging Influenza A Virus Infections in Swine

Location: Virus and Prion Research

Title: Occupationally exposed and general population antibody profiles to influenza A viruses circulating in swine as an indication of zoonotic risk

Author
item SNYDER, CELESTE - Oak Ridge Institute For Science And Education (ORISE)
item JANZEN, GARRETT - Oak Ridge Institute For Science And Education (ORISE)
item CIACCI ZANELLA, GIOVANNA - Oak Ridge Institute For Science And Education (ORISE)
item MORAES, DANIAL - Iowa State University
item SILVA, GUSTAVO - Iowa State University
item SANTOS, JEFFERSON - University Of Pennsylvania
item DRAPEAU, ELIZABETH - University Of Pennsylvania
item HENSLEY, SCOTT - University Of Pennsylvania
item Anderson, Tavis
item GAUGER, PHILLIP - Iowa State University
item Baker, Amy

Submitted to: Emerging Infectious Diseases
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/5/2026
Publication Date: 7/15/2026
Citation: Snyder, C.A., Janzen, G.M., Ciacci Zanella, G., Moraes, D.C., Silva, G.S., Santos, J., Drapeau, E.M., Hensley, S.E., Anderson, T.K., Gauger, P.C., Baker, A.L. 2026. Occupationally exposed and general population antibody profiles to influenza A viruses circulating in swine as an indication of zoonotic risk. Emerging Infectious Diseases. https://doi.org/10.3201/eid3208.251995.
DOI: https://doi.org/10.3201/eid3208.251995

Interpretive Summary: Influenza viruses that circulate in pigs can sometimes infect people and caused the 2009 H1N1 pandemic, creating a potential public health threat for currently circulating swine strains. To better understand this risk, we measured how well people’s existing immunity shaped by past infections or seasonal influenza vaccination can recognize influenza viruses currently found in U.S. pigs. We found that many people, including those who work closely with pigs, had little to no antibodies against several swine influenza strains. This means the human population could be vulnerable if one of these viruses began spreading in humans. However, people who received the human seasonal influenza vaccine generally showed stronger protection to many, but not all, swine strains, suggesting that receiving the human seasonal vaccine may help lower the chance of spread from pigs to people. These results prioritize swine strains for human pandemic preparedness through vaccine updates and control programs in swine and highlight the importance of human seasonal vaccine for people exposed to swine.

Technical Abstract: Individuals with occupational exposure to swine may have disproportionate risk for zoonosis with swine influenza A virus (IAV). To evaluate human antibody responses, sera or plasma from swine veterinarians, swine farm employees, and the general population were tested by hemagglutination inhibition (HI) assays against representative swine and human seasonal influenza vaccine strains. HI data were analyzed by antigenic cartography to assess strain relationships, and reproduction number modeling to evaluate pandemic potential using age-stratified immunity profiles. Occupationally exposed groups had lower human seasonal vaccine uptake (45.5% vs 70%) and significantly lower odds of seropositivity to several H1 and H3 from swine compared to general population cohorts. One swine strain exhibited significant antigenic drift (3.62 AU) from its nearest vaccine strain. Multiple strains required lower R0 thresholds for pandemic spread (1.09-1.35) than recorded pandemic strains (1.46-1.80). This demonstrates that population immunity gaps heighten zoonotic risk to circulating swine H1 and H3 strains.