[Immunogenicity analysis of sequential inoculation of different strains of poliomyelitis vaccines in Shanghai]

Objective: To evaluate the immunogenicity of different strains of inactivated poliomyelitis vaccines (IPV) by sequential program. Methods: This parallel-group controlled trial was conducted in immunization clinics in Shanghai from March 2016 to September 2017. Sabin strains inactivated poliomyelitis vaccines (sIPV), WPV strains inactivated poliomyelitis vaccines (wIPV) and live poliomyelitis Type Ⅰ Type Ⅲ vaccine (bOPV) as the investigational vaccine were used at 2, 3, 4 months old in 325 infants in Shanghai. Infants vaccinated by four sequential program were divided into 4 groups: sIPV+sIPV+bOPV, sIPV+wIPV+bOPV, wIPV+sIPV+bOPV and wIPV+wIPV+bOPV. A total of 230 investigators’ blood samples were collected before primary immunization and 163 investigators’ blood samples were collected after primary immunization. A total of 151 investigators (36, 44, 30 and 41 in each group) finished primary immunization and blood sampling before and after the primary immunization. The geometric mean titer (GMT) of poliovirus typesⅠ and Ⅲ neutralizing antibody was tested and calculated, and the positive results of antibody before and after primary immunization were analyzed. Results: Among the 151 investigators, the age were (2.27±0.61) months and birth weight were (3.27±0.43) kg, and 70 were male. The positive rates of typeⅠwas 98.68% (149 cases), and type Ⅲ was 97.35% (147 cases); the number of investigators tested in each group was 36, 44, 30 and 41, respectively; the positive rates of typeⅠwas 97.22% (35 cases), 100.00% (44 cases), 96.67% (29 cases) and 100.00% (41 cases) ( P= 0.345); the positive rates of type Ⅲ were 97.22% (35 cases), 95.45% (42 cases), 96.67% (29 cases) and 100.00% (41 cases) ( P= 0.614). Conclusion: Using sIPV and wIPV simultaneously or alternately for sequential immunization of poliomyelitis vaccines showed good immunogenicity for infants at appropriate age.