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Incidence of influenza virus infections in children in Hong Kong in a 3-year randomized placebo-controlled vaccine study, 2009-2012.
Clin Infect Dis 2014; 59(4):517-24CI

Abstract

BACKGROUND

School-aged children suffer high rates of influenza virus infections and associated illnesses each year, and are a major source of transmission in the community. However, information on the cumulative incidence of infection in specific epidemics is scarce, and there are limited studies with sufficient follow-up to identify the strength and duration of protection against reinfection.

METHODS

We randomly allocated children 5-17 years of age to receive trivalent inactivated influenza vaccine (TIV) or placebo from September 2009 through January 2010, and then conducted follow-up for 3 years including regular collection of sera, symptom diaries, and collection of nose and throat swabs during illness episodes in participants or their household members.

RESULTS

Of 796 children initially randomized, 484 continued to participate for all 3 years. In unvaccinated children, cumulative incidence of infection was estimated to be 59% in the first wave of H1N1pdm09 in 2009-2010, and 7%, 14%, 20%, and 31% in subsequent epidemics of H3N2 (2010), H1N1pdm09 (2011), B (2012), and H3N2 (2012), respectively. Infection with H1N1pdm09 in 2009-2010 and H3N2 in 2010 was associated with protection against infection with subsequent epidemics of the same subtype in 2011 and 2012, respectively, but we found no evidence of heterotypic or heterosubtypic protection against infection.

CONCLUSIONS

We identified substantial incidence of influenza virus infections in children in Hong Kong in 5 major epidemics over a 3-year period, and evidence of homosubtypic but not heterosubtypic protection following infection.

CLINICAL TRIALS REGISTRATION

NCT00792051.

Authors+Show Affiliations

Division of Epidemiology and Biostatistics, School of Public Health.Division of Public Health Laboratory Sciences, School of Public Health Centre for Influenza Research.Division of Epidemiology and Biostatistics, School of Public Health.Department of Microbiology.Division of Epidemiology and Biostatistics, School of Public Health.Division of Epidemiology and Biostatistics, School of Public Health.Division of Public Health Laboratory Sciences, School of Public Health Centre for Influenza Research.Division of Epidemiology and Biostatistics, School of Public Health.Division of Epidemiology and Biostatistics, School of Public Health.Department of Ecology and Evolutionary Biology, Princeton University, New Jersey.Division of Community Medicine and Public Health Practice, School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong Special Administrative Region, China.Division of Public Health Laboratory Sciences, School of Public Health Centre for Influenza Research.Division of Community Medicine and Public Health Practice, School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong Special Administrative Region, China.

Pub Type(s)

Clinical Trial
Journal Article
Randomized Controlled Trial
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

24825868

Citation

Cowling, Benjamin J., et al. "Incidence of Influenza Virus Infections in Children in Hong Kong in a 3-year Randomized Placebo-controlled Vaccine Study, 2009-2012." Clinical Infectious Diseases : an Official Publication of the Infectious Diseases Society of America, vol. 59, no. 4, 2014, pp. 517-24.
Cowling BJ, Perera RA, Fang VJ, et al. Incidence of influenza virus infections in children in Hong Kong in a 3-year randomized placebo-controlled vaccine study, 2009-2012. Clin Infect Dis. 2014;59(4):517-24.
Cowling, B. J., Perera, R. A., Fang, V. J., Chan, K. H., Wai, W., So, H. C., ... Leung, G. M. (2014). Incidence of influenza virus infections in children in Hong Kong in a 3-year randomized placebo-controlled vaccine study, 2009-2012. Clinical Infectious Diseases : an Official Publication of the Infectious Diseases Society of America, 59(4), pp. 517-24. doi:10.1093/cid/ciu356.
Cowling BJ, et al. Incidence of Influenza Virus Infections in Children in Hong Kong in a 3-year Randomized Placebo-controlled Vaccine Study, 2009-2012. Clin Infect Dis. 2014 Aug 15;59(4):517-24. PubMed PMID: 24825868.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Incidence of influenza virus infections in children in Hong Kong in a 3-year randomized placebo-controlled vaccine study, 2009-2012. AU - Cowling,Benjamin J, AU - Perera,Ranawaka A P M, AU - Fang,Vicky J, AU - Chan,Kwok-Hung, AU - Wai,Winnie, AU - So,Hau Chi, AU - Chu,Daniel K W, AU - Wong,Jessica Y, AU - Shiu,Eunice Y, AU - Ng,Sophia, AU - Ip,Dennis K M, AU - Peiris,J S Malik, AU - Leung,Gabriel M, Y1 - 2014/05/13/ PY - 2014/5/15/entrez PY - 2014/5/16/pubmed PY - 2015/3/31/medline KW - immunity KW - incidence rates KW - influenza virus KW - vaccination SP - 517 EP - 24 JF - Clinical infectious diseases : an official publication of the Infectious Diseases Society of America JO - Clin. Infect. Dis. VL - 59 IS - 4 N2 - BACKGROUND: School-aged children suffer high rates of influenza virus infections and associated illnesses each year, and are a major source of transmission in the community. However, information on the cumulative incidence of infection in specific epidemics is scarce, and there are limited studies with sufficient follow-up to identify the strength and duration of protection against reinfection. METHODS: We randomly allocated children 5-17 years of age to receive trivalent inactivated influenza vaccine (TIV) or placebo from September 2009 through January 2010, and then conducted follow-up for 3 years including regular collection of sera, symptom diaries, and collection of nose and throat swabs during illness episodes in participants or their household members. RESULTS: Of 796 children initially randomized, 484 continued to participate for all 3 years. In unvaccinated children, cumulative incidence of infection was estimated to be 59% in the first wave of H1N1pdm09 in 2009-2010, and 7%, 14%, 20%, and 31% in subsequent epidemics of H3N2 (2010), H1N1pdm09 (2011), B (2012), and H3N2 (2012), respectively. Infection with H1N1pdm09 in 2009-2010 and H3N2 in 2010 was associated with protection against infection with subsequent epidemics of the same subtype in 2011 and 2012, respectively, but we found no evidence of heterotypic or heterosubtypic protection against infection. CONCLUSIONS: We identified substantial incidence of influenza virus infections in children in Hong Kong in 5 major epidemics over a 3-year period, and evidence of homosubtypic but not heterosubtypic protection following infection. CLINICAL TRIALS REGISTRATION: NCT00792051. SN - 1537-6591 UR - https://www.unboundmedicine.com/medline/citation/24825868/Incidence_of_influenza_virus_infections_in_children_in_Hong_Kong_in_a_3_year_randomized_placebo_controlled_vaccine_study_2009_2012_ L2 - https://academic.oup.com/cid/article-lookup/doi/10.1093/cid/ciu356 DB - PRIME DP - Unbound Medicine ER -