Influence of Pre-vaccination Antibody Titer on Immunogenicity and Immune Persistence of Influenza A(H1N1) Vaccine

Objective To explore the impact of pre-vaccination antibody titer on immunogenicity and immune persistence of influenza A(H1N1) vaccine.Methods Multi-stage random sampling method was adopted to select 350 monitoring objects from people aged 3-5 years,6-10 years,11-15 years,16-20 years,21-40 years,41-60 years and over 60 years.The micro-hemagglutination inhibition(HI) experiment was used to determine their antibody levels before the vaccine inoculation,28 days and 6 months after the vaccination.The mean titer of antibody,seroconversion rate and seroprotection rate were calculated.The relationships between the pre-vaccination antibody titer and seroconversion rate,seroprotection rate were analyzed.Results Before the vaccination,the mean titer of HI antibody in the monitoring crowd was 1:6.65 and the seroprotection rate was 17.1%.28 days and 6 months after the vaccination,the mean titer of HI antibody,seroconversion rate and seroprotection rate exceeded the standards of the EMEA and the U.S.FDA.The pre-vaccination antibody titer was negatively correlated with the seroconversion rates of 28 days and 6 months after the vaccination,but had no correlation with the seroprotection rate.Conclusions In order to improve the seroprotection rate and protect the susceptible population during the influenza A(H1N1) pandemic,pre-vaccination antibody titer can be ignored when influenza A(H1N1) vaccine uses in the susceptible;meanwhile,good immunogenicity and immune persistence can be obtained.