Sero-conversion Study for a Two-dose Schedule of Sabin IPV in China

In April 2017, WHO/SAGE recommended that a two-dose, IPV-only schedule can be used after polio eradication, with a schedule seroconversion target of at least 90%. The recommendation was based in part on a study conducted in Cuba using Salk-IPV at 4 months and 8 months of age. However, for domestic Sabin IPVs, there are no such data to support a 2-dose schedule among Chinese infants.Two Sabin IPV products that are available to China's National Immunization Program - produced by Kunming Bio institute and China National Biotec Group (CNBG).The monitoring study on sIPV produced by Kunming Bio institute has already applied for approval.This study aims to obtain the direct domestic IPV vaccine monitoring data for the CNBG products, and provide scientific evidence for the National Immunization Program and long-term polio vaccine immunization policy.

The overall objective of this research is to determine the seroconversion rates of two reduced Sabin IPV schedules in Chinese children - a 2-dose schedule and a 3-dose schedule.

The specific objectives of the study are to:

• Determine whether the seroconversion rate is above 90% with a 2-dose Sabin IPV schedule, with the first dose given at 4 months and the second dose given ≥4 months after the first dose.
• Measure neutralizing antibody titers against poliovirus type I, II and III among two-dose Sabin IPV alone schedule, compared with three-dose Sabin IPV alone schedule.

Inclusion criteria

• Parent or legal guardian agree to participate in our study.
• The family is living locally with legal residency status.

Exclusion criteria

• Parent or legal guardian does not agree to participate in our study.
• The potential subject has received IPV or OPV before 4 months of age in the two-dose schedule group.
• The potential subject has one or more contraindications to IPV (although we will note the contraindications).