Population Serologic Immunity to Human and Avian H2N2 Viruses in the United States and Hong Kong for Pandemic Risk Assessment. (12th May 2018)

• Record Type: Journal Article
• Authors: Babu, Tara M; Perera, Ranawaka A P M; Wu, Joseph T; Fitzgerald, Theresa; Nolan, Carolyn; Cowling, Benjamin J; Krauss, Scott; Treanor, John J; Peiris, Malik
• Is Part Of: Journal of infectious diseases. Volume 218:Number 7(2018)
• Page Start: 1054
• Page End: 1060
• Publication Date: 2018-05-12
• Subjects: H2 -- influenza -- serology -- effective reproduction number -- pandemic risk assessment; Communicable diseases -- Periodicals; Diseases -- Causes and theories of causation -- Periodicals; Medicine -- Periodicals; Communicable Diseases -- Periodicals; Electronic journals; 616.9
• DOI: 10.1093/infdis/jiy291
• Languages: English
• ISSNs: 0022-1899

Abstract

Abstract: Background: Influenza A pandemics cause significant mortality and morbidity. H2N2 viruses have caused a prior pandemic, and are circulating in avian reservoirs. The age-related frequency of current population immunity to H2 viruses was evaluated. Methods: Hemagglutinin inhibition (HAI) assays against historical human and recent avian influenza A(H2N2) viruses were performed across age groups in Rochester, New York, and Hong Kong, China. The impact of existing cross-reactive HAI immunity on the effective reproduction number was modeled. Results: One hundred fifty individual sera from Rochester and 295 from Hong Kong were included. Eighty-five percent of patients born in Rochester and Hong Kong before 1968 had HAI titers ≥1:40 against A/Singapore/1/57, and >50% had titers ≥1:40 against A/Berkeley/1/68. The frequency of titers ≥1:40 to avian H2N2 A/mallard/England/727/06 and A/mallard/Netherlands/14/07 in subjects born before 1957 was 62% and 24%, respectively. There were no H2 HAI titers >1:40 in individuals born after 1968. These levels of seroprevalence reduce the initial reproduction number of A/Singapore/1/1957 or A/Berkeley/1/68 by 15%–20%. A basic reproduction number (R0 ) of the emerging transmissible virus <1.2 predicts a preventable pandemic. Conclusions: Population immunity to H2 viruses is insufficient to block epidemic spread of H2 virus. An H2N2 pandemic would have lower impact in those born before 1968. Abstract : Mathematical modeling was performed, using population immunity against candidate pandemic H2 influenza strains, to predict risk for pandemic infection. Population immunity is insufficient to block epidemic spread of H2 virus, but would have lower impact in those born before 1968.