A Meta-analysis of the incidence of influenza reported during year 2005 to 2012 in China

Abstract

Objective To investigate the epidemic patterns and the characteristics of influenza in China through a Meta-analysis based on the studies published in domestic literatures. Methods Related articles published during 2005 to 2012 were screened out from domestic databases and analyzed through a Meta-analysis with Review Manager 5.0 software. Results Twenty-two articles covering 957 901 patients with influenza-like-illness (ILI) and 148 233 pathogen samples were screened out according to the inclusion criteria. No significant difference with the ILI diagnosis rate was found between subjects at age 0-4 years and those at age 15-59 years. Higher ILI diagnosis rates were observed in those two groups as compared with subjects elder than 60 years old. Most of the pathogen samples were carried by subjects aged 25-59 years. More influenza virus strains were isolated in 2009 as compared with those of the seven other years (OR=2.25, 95%CI=1.27-3.70). There was statistical difference between the numbers of influenza A H1N1 and seasonal influenza A strains (OR=2.25, 95%CI=1.30-3.91). Significant difference was also observed between the numbers of influenza A and influenza B strains (OR=4.05, 95%CI=2.53-6.47). Conclusion There was significant difference with the diagnosis rate between subjects aged 0-4 years and those aged ≥60 years. More attention should be paid to people at high risk of infection (0-4 years old and ≥60 years old) and those at 25-29 years with high mobility and social intercourse for the timely prevention and control of pandemic influenza. The detection rate of influenza virus strains was increased during the outbreak of novel influenza A H1N1 infection in 2009. After that outbreak, the detection rate of novel influenza A H1N1 strains was 2.25 times the rate of seasonal influenza strains. The detection rate of influenza A was 4.05 times the rate of influenza B virus strains. Therefore, it is necessary to strengthen the surveillance for influenza A virus and other epidemic influenza virus strains. Key words: Influenza virus; Influenza-like-illness; Meta-analysis