Analysis of polio antibody levels in healthy population in Beijing in 2007

OBJECTIVE To investigate the poliomyelitis antibody level in healthy people in Beijing. METHODS 10 age groups (0, 1 to 4, 5 to 9, 10 to 14, 15 to 19, 20 to 24, 25 to 29, 30 to 34, 35 to 39, and > or = 40) were sampled by the Multi-stage stratified sampling method in 7 districts in Beijing, and 1552 sera from healthy population were collected. The poliomyelitis antibody was determined with microcell neutralization method. RESULTS The neutralized antibody-positive rate for polio I, II, III were 97.04%, 97.29% and 91.04% respectively, the geometric mean titers (GMT) were 1:70.05, 1:54.60, and 1:31.83 respectively. A trend of decreasing was observed in the GMTs with increasing age and years after immunization. There were no significant differences in antibody levels between different gender, residents or regions. The results of multiple-factors analysis showed that the GMTs were significantly associated with age and the years after immunization. CONCLUSION A stable immunization barrier has been established in healthy population in Beijing.