Monitoring of Polio Antibody Levels in Different Regions of Chongqing under Existing Immunization Programs

Objective To evaluate the neutralizing antibody levels of poliomyelitis for newborns after primary polio immunization with different immunization schedules in Chongqing, and to provide basis for the prevention and control strategy of poliomyelitis.Method Four regions in Chongqing were randomly divided into two different vaccination schedules: 3IPV and 2IPV+bOPV, and tested for serum polio neutralizing antibodies 1~6 months after primary vaccination.Result For different sequential immunization schedules: The positive rates of poliovirus type I in the 2IPV+bOPV group and 3IPV group were 99.46%、100%, respectively(P＞0.05),and the median of antibody titer of 2IPV+bOPV group and 3IPV group were 2048 and 128, respectively (P<0.05); The positive rates of poliovirus type Ⅱ in the 2IPV+bOPV group and 3IPV group were 99.83%、100%, respectively(P＜0.05),and the median of antibody titer of 2IPV+bOPV group and 3IPV group were 96 and 192, respectively (P<0.05); The positive rates of poliovirus type Ⅲ in the 2IPV+bOPV group and 3IPV group were 99.46%、99.55%, respectively(P＞0.05),and the median of antibody titer of 2IPV+bOPV group and 3IPV group were 2048 and 256, respectively (P<0.05).Conclusion Different immunization schedules are one of the most important influencing factors. The poliovirus type Ⅱ antibody levels of 3IPV group are higher than those of the 2IPV-bOPV group. To reduce and prevent VAPP and cVDPV2 for poliovirus type Ⅱ, 3IPV is a better choice.