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Partial protection against 2009 pandemic influenza A (H1N1) of seasonal influenza vaccination and related regional factors: Updated systematic review and meta-analyses.

ABSTRACT: This updated systematic review and meta-analyses aims to systematically evaluate the cross-protection of seasonal influenza vaccines against the 2009 pandemic A (H1N1) influenza infection, and investigate the potential effect of the influenza strains circulating previous to the pandemic on the association between vaccine receipt and pandemic infection. In addition, subgroup analysis was performed based on the study locations and previous circulating influenza viruses. Relevant articles in English and Chinese from 2009 to October 2013 were systematically searched, and 21 eligible studies were included. For case-control studies, an insignificant 20% reduced risk for pandemic influenza infection based on combined national data (OR = 0.80; 95%CI: 0.60, 1.05) was calculated for people receiving seasonal influenza vaccination. However, for RCTs, an insignificant increase in the risk of seasonal influenza vaccines was observed (RR = 1.27; 95% CI: 0.46, 3.53). For the subgroup analysis, a significant 35% cross-protection was observed in the subgroup where influenza A outbreaks were detected before the 2009 pandemic. Moreover, the results indicated that seasonal influenza vaccination may reduce the risk of influenza-like illnesses (ILIs) (RR = 0.91; 95% CI: 0.84, 0.99). Our findings partially support the hypothesis that seasonal vaccines may offer moderate cross-protection for adults against laboratory-confirmed pandemic influenza A (H1N1) infection and ILIs. Further immunological studies are needed to understand the mechanism underlying these findings.

SUBMITTER: Li ZY

PROVIDER: S-EPMC4514212 | biostudies-literature | 2015

REPOSITORIES: biostudies-literature

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Partial protection against 2009 pandemic influenza A (H1N1) of seasonal influenza vaccination and related regional factors: Updated systematic review and meta-analyses.

Li Zhi-yuan ZY Chen Jin-yan JY Zhang Yan-ling YL Fu Wei-ming WM

Human vaccines & immunotherapeutics 20150101 6

This updated systematic review and meta-analyses aims to systematically evaluate the cross-protection of seasonal influenza vaccines against the 2009 pandemic A (H1N1) influenza infection, and investigate the potential effect of the influenza strains circulating previous to the pandemic on the association between vaccine receipt and pandemic infection. In addition, subgroup analysis was performed based on the study locations and previous circulating influenza viruses. Relevant articles in Englis ...[more]

PMID: 25692308

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Project description:BackgroundThe immunogenicity of 2009 pandemic influenza A(H1N1) (pH1N1) vaccines and the effect of previous influenza vaccination is a matter of current interest and debate. We measured the immune response to pH1N1 vaccine in HIV-infected patients and in healthy controls. In addition we tested whether recent vaccination with seasonal trivalent inactivated vaccine (TIV) induced cross-reactive antibodies to pH1N1. (clinicaltrials.gov Identifier:NCT01066169).Methods and findingsIn this single-center prospective cohort study MF59-adjuvanted pH1N1 vaccine (Focetria®, Novartis) was administered twice to 58 adult HIV-infected patients and 44 healthy controls in November 2009 (day 0 and day 21). Antibody responses were measured at baseline, day 21 and day 56 with hemagglutination-inhibition (HI) assay. The seroprotection rate (defined as HI titers ≥ 1 : 40) for HIV-infected patients was 88% after the first and 91% after the second vaccination. These rates were comparable to those in healthy controls. Post-vaccination GMT, a sensitive marker of the immune competence of a group, was lower in HIV-infected patients. We found a high seroprotection rate at baseline (31%). Seroprotective titers at baseline were much more common in those who had received 2009-2010 seasonal TIV three weeks prior to the first dose of pH1N1 vaccine. Using stored serum samples of 51 HIV-infected participants we measured the pH1N1 specific response to 2009-2010 seasonal TIV. The seroprotection rate to pH1N1 increased from 22% to 49% after vaccination with 2009-2010 seasonal TIV. Seasonal TIV induced higher levels of antibodies to pH1N1 in older than in younger subjects.ConclusionIn HIV-infected patients on combination antiretroviral therapy, with a median CD4+ T-lymphocyte count above 500 cells/mm(3), one dose of MF59-adjuvanted pH1N1 vaccine induced a high seroprotection rate comparable to that in healthy controls. A second dose had a modest additional effect. Furthermore, seasonal TIV induced cross-reactive antibodies to pH1N1 and this effect was more pronounced in older subjects.

Dataset Information

Partial protection against 2009 pandemic influenza A (H1N1) of seasonal influenza vaccination and related regional factors: Updated systematic review and meta-analyses.

Publications

Partial protection against 2009 pandemic influenza A (H1N1) of seasonal influenza vaccination and related regional factors: Updated systematic review and meta-analyses.

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