1. Protective efficacy of seasonal influenza vaccination against seasonal and pandemic influenza virus infection during 2009 in Hong Kong.
- Author
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Cowling BJ, Ng S, Ma ES, Cheng CK, Wai W, Fang VJ, Chan KH, Ip DK, Chiu SS, Peiris JS, and Leung GM
- Subjects
- Adolescent, Antibodies, Neutralizing blood, Antibodies, Viral blood, Child, Female, Hemagglutination Inhibition Tests, Hong Kong epidemiology, Humans, Influenza Vaccines administration & dosage, Influenza, Human virology, Male, Neutralization Tests, Nose virology, Pharynx virology, Placebos administration & dosage, RNA, Viral genetics, RNA, Viral isolation & purification, Reverse Transcriptase Polymerase Chain Reaction, Vaccines, Inactivated administration & dosage, Vaccines, Inactivated immunology, Cross Protection, Influenza Vaccines immunology, Influenza, Human epidemiology, Influenza, Human prevention & control, Orthomyxoviridae isolation & purification, Pandemics, Vaccination methods
- Abstract
Background: The relationship between seasonal influenza vaccine and susceptibility to 2009 pandemic A/H1N1 virus infection is not fully understood., Methods: One child 6-15 years of age from each of 119 households was randomized to receive 1 dose of inactivated trivalent seasonal influenza vaccine (TIV) or saline placebo in November 2008. Serum samples were collected from study subjects and their household contacts before and 1 month after vaccination (December 2008), after winter (April 2009) and summer influenza (September-October 2009) seasons. Seasonal and pandemic influenza were confirmed by serum hemagglutinination inhibition, viral neutralization titers, and reverse-transcription polymerase chain reaction performed on nasal and throat swab samples collected during illness episodes., Results: TIV recipients had lower rates of serologically confirmed seasonal A/H1N1 infection (TIV group, 8%; placebo group, 21%; P=.10) and A/H3N2 infection (7% vs 12%; P=A9), but higher rates of pandemic A/H1N1 infection (32% vs 17%; [Formula: see text]). In multivariable analysis, those infected with seasonal influenza A during the study had a lower risk of laboratory-confirmed pandemic A/H1N1 infection (adjusted odds ratio [OR], 0.35; 95% confidence interval [CI], 0.14-0.87), and receipt of seasonal TIV was unassociated with risk of pandemic A/H1N1 infection (adjusted OR, 1.11; 95% CI, 0.54-2.26)., Conclusions: TIV protected against strain-matched infection in children. Seasonal influenza infection appeared to confer cross-protection against pandemic influenza. Whether prior seasonal influenza vaccination affects the risk of infection with the pandemic strain requires additional study., Clinical Trials Registration: ClinicalTrials.gov number NCT00792051 .
- Published
- 2010
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