Table 4 RECAMP-OPV - potential effect modifiers
Effect modifiers | Rationale |
|---|---|
Sex | Previous studies have demonstrated that the effect of OPV is stronger in boys than girls [4, 15, 47]. |
One vs two doses (2nd dose 1 month after enrolment) | Observational studies indicate that additional doses of OPV offer additional benefits [15]. |
Age at first dose of OPV | A prior study has indicated that the effect of subsequent vaccines may vary with the age at which the gut was primed [16]. |
Season of enrolment | Some interventions (eg MV and Vitamin A) have stronger effects when given in the dry season [29, 48]. We will investigate whether the effect of OPV varies for children enrolled in the dry season (December–May) versus children enrolled in the rainy season (June–November) |
Vitamin A supplements | Vitamin A supplementation may amplify the NSEs of vaccines [49, 50]. We will examine whether the effect of OPV vary before and after being eligible for vitamin A supplementation after enrolment |
Prior OPV campaign | Repeated doses of OPV offer additional benefits [15]. If OPV campaigns take place during the study, we will assess whether the effect is similar in children having been exposed/not exposed to prior OPV campaigns. |