Affiliations: *Children’s Hospital, Department of Medical Services
**Virus Research Institute, Department of Medical Sciences,
Ministry of Public Health
Source: Thai Journal of Pediatrics 1996; 35(2): 125-133
A prospective study of polio antibody response after routine immunization with trivalent oral polio vaccine (OPV) was done at the Children’s Hospital, Bangkok between June and November 1994, The subjects consisted of 105 healthy children who came regularly and had OPV immunization according to the Expanded Program of Immunization (EPI) schedule (at 2, 4, 6, 18 and 48 months of age) at the Well Baby Clinic.The seroconversion rates to all 3 types of polioviruses after primary series of OPV (3 doses) at 3, 6 and 12 months were 86.67, 88.57 and 94.29% respectively. More Than 90% of children who seroconverted had high antibody titer of > 1:32. All childern had protective antibody level to type 2 while 88-97% and 91-97% had to type 1 and type 3 respectively. After first OPV booster, 97 and 94% of children had seroconversion to all 3 types of polioviruses at 1 and 30 months later respectively. All children had seroconversion to all 3 types of polioviruses after second OPV booster and most of them had high antibody titer of > 1:32. In conclusion from this study, the currently OPV and EPI schedule used are appropriate for Thai children provided that the vaccines handling and storage should be optimal until the time of administration.