Monovalent Oral Poliovirus Vaccine Type 1 Intestinal and Humoral Immunity Study

The risk for circulating vaccine‐derived poliovirus (cVDPV) will increase in the years immediately after the cessation of oral poliovirus vaccine (OPV) use in routine immunization programs. Judicious use of type‐specific monovalent OPV (mOPV) will be necessary for outbreak response to prevent further paralytic infections and transmission; however, data on the intestinal and humoral immunity induced by mOPV1 are very limited. Furthermore, the additional benefit of fractional dose inactivated poliovirus vaccine (fIPV) on type 1 immunity when given with mOPV1 is unclear. Data on intestinal and humoral immunity of mOPV type 1 (mOPV1) and combination use of mOPV1 and fractional dose of IPV (fIPV) are urgently needed and would be used to inform guidelines for type 1 outbreak response in a post‐OPV world. In the immediate future, a strategy of shifting from bivalent OPV (bOPV) to mOPV1 as part of supplemental immunization activities in endemic countries is under consideration but data on intestinal and humoral immunity to support this change does not exist. This trial is designed to address both areas in which data are lacking. Healthy infants 5 weeks of age will be enrolled at two study clinics in Dhaka, Bangladesh, and randomized to one of four study arms: mOPV1 + fIPV at 6 weeks, mOPV1 + fIPV at 14 weeks, mOPV1 only, and bOPV only. Infants will be followed‐up until 18 weeks of age by clinic and household visits. Blood and stool specimens will be collected to test for vaccine response (humoral immunity) and vaccine virus shedding (intestinal immunity).