Post immunization sero-antibody level to circulating influenza viruses induced by seasonal influenza vaccine in China

Objective To understand the post immunization sero antibody level to circulating influenza viruses induced by seasonal influenza vaccine and the matching of vaccine strains with circulating strains. Methods Pre and post immunization serum samples were collected from people in different age groups. Hemagglutination inhibition(HI) assay with circulating strain and vaccine strain as antigen was conducted to detect the serum antibody level. Results The antibody geometrical mean titer(GMT) of trivalent influenza vaccine to influenza A(H1N1) pdm09 strain in China was lower than that to vaccine strain, the proportion of serum samples with antibody titer 40 was ranged from 57.0% to 63.3%. The GMT of antibody induced by influenza vaccine to circulating H3N2 influenza strains was similar to that to vaccine strain, the proportion of serum samples with antibody titer 40 ranged from 57.6% to 63.0%. The GMT of antibody induced by influenza vaccine to circulating influenza B strain was lower than that to vaccine strain, but was more than 50% of the GMT antibody of the vaccine virus. The adult group had relatively higher serum antibody level than the other age groups. Conclusion The composition of seasonal influenza vaccine of 2013-2014 matched with the circulating influenza A(H1N1) pdm09 and influenza B strains Yamagata lineage; the mismatching of influenza A(H3N2) vaccine strain with the circulating influenza A(H3N2) strain would reduce the effectiveness of the vaccine.