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. 2022 May;28(5):977-985.
doi: 10.3201/eid2805.211965.

Determining Existing Human Population Immunity as Part of Assessing Influenza Pandemic Risk

Jonathan Tin Lai Cheung, Tim K Tsang, Hui-Ling Yen, Ranawaka A P M Perera, Chris Ka Pun Mok, Yong Ping Lin, Benjamin J Cowling, Malik Peiris

Determining Existing Human Population Immunity as Part of Assessing Influenza Pandemic Risk

Jonathan Tin Lai Cheung et al. Emerg Infect Dis. 2022 May.

Abstract

Zoonotic influenza infections continue to threaten human health. Ongoing surveillance and risk assessment of animal viruses are needed for pandemic preparedness, and population immunity is an important component of risk assessment. We determined age-stratified hemagglutinin inhibition seroprevalence against 5 swine influenza viruses circulating in Hong Kong and Guangzhou in China. Using hemagglutinin inhibition seroprevalence and titers, we modeled the effect of population immunity on the basic reproduction number (R0) if each virus were to become transmissible among humans. Among 353 individual serum samples, we reported low seroprevalence for triple-reassortant H1N2 and Eurasian avian-like H1N1 influenza viruses, which would reduce R0 by only 18%-20%. The smallest R0 needed to cause a pandemic was 1.22-1.24, meaning existing population immunity would be insufficient to block the spread of these H1N1 or H1N2 variants. For human-origin H3N2, existing population immunity could suppress R0 by 47%, thus reducing pandemic risk.

Keywords: China; Hong Kong; hemagglutination inhibiting antibody; hemagglutinin; influenza; neuraminidase; pandemics; population immunity; reproduction numbers; risk assessment; seroprevalence; swine; swine flu; viruses; zoonoses.

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Figures

Figure 1
Figure 1
Seroprevalence of hemagglutination inhibition antibodies to different swine influenza viruses, by age group and location, in study to determine existing human population immunity as part of assessing influenza pandemic risk. A) A/swine/Hong Kong/NS4003/2016 (EA); B) A/swine/Guangdong/104/2013 (EA); C) A/swine/Hong Kong/NS301/2013 (TR); D) A/swine/Hong Kong/1436/2016 (pdm09); E) A/swine/Hong Kong/4348/2016 (BD-like H3). BD, Binh Duong; EA, Eurasian avian-like; pdm09, 2009 pandemic strain; TR, triple-reassortant.
Figure 2
Figure 2
Estimations of overall population-level immunity against H1 and H3 viruses and the potential effect of population immunity on reproduction number in study to determine existing human population immunity as part of assessing influenza pandemic risk. Error bars represent the 95% credible intervals of the estimates. Data are shown from A/Swine/Hong Kong/NS4003/2016 (EA, H1N1) (NS4003), A/Swine/Guangdong/104/2013 (EA, H1N1) (GD104), A/Swine/Hong Kong/NS301/2013 (TR, H1N2) (NS301), A/Swine/Hong Kong/1436/2016 (pdmH1N1) (TS1436), and A/Swine/Hong Kong/4348/2016 (BD-like H3N2) (TS4348).
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References

    1. Monto AS, Webster RG. Influenza pandemics: history and lessons learned. In: Webster RG, Monto AS, Braciale TJ, Lamb RA, editors. Textbook of influenza. Hoboken (NJ): John Wiley and Sons; 2013. p. 20–34.
    1. Mena I, Nelson MI, Quezada-Monroy F, Dutta J, Cortes-Fernández R, Lara-Puente JH, et al. Origins of the 2009 H1N1 influenza pandemic in swine in Mexico. eLife. 2016;5:e16777. 10.7554/eLife.16777 - DOI - PMC - PubMed
    1. Wu JT, Ma ES, Lee CK, Chu DK, Ho PL, Shen AL, et al. The infection attack rate and severity of 2009 pandemic H1N1 influenza in Hong Kong. Clin Infect Dis. 2010;51:1184–91. 10.1086/656740 - DOI - PMC - PubMed
    1. Jernigan DB, Cox NJ. Human influenza: one health, one world. In: Webster RG, Monto AS, Braciale TJ, Lamb RA, editors. Textbook of influenza. Hoboken (NJ): John Wiley and Sons; 2013. p. 1–19.
    1. Cox NJ, Trock SC, Burke SA. Pandemic preparedness and the influenza risk assessment tool (IRAT). Curr Top Microbiol Immunol. 2014;385:119–36. 10.1007/82_2014_419 - DOI - PubMed

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