Macklin GR, Grassly NC, Sutter RW, et al. - Researchers performed determination of comparative estimates of humoral and intestinal mucosal immunity against poliovirus associated with different routine immunization schedules. A random-effect meta-analysis with single proportions and a network meta-analysis in a Bayesian framework were performed to integrate direct and indirect data. For assessment of humoral immunity and intestinal immunity, eligible works were 17 studies with a maximum of 8,279 evaluable infants and eight studies with 4,254 infants, respectively. For serotype 2, the risk ratio (RR) of seroconversion was 0·14 after three doses of bivalent oral poliovirus vaccines (OPVs) vs three doses of trivalent OPVs. The RR increased to 0·85 (0·75–1·0) and 1·1 (0·98–1·4) following the addition of one or two full doses of an inactivated poliovirus vaccine (IPV) after a bivalent OPV schedule, respectively. However, the addition of an IPV to bivalent OPV schedules led to no significant increase in intestinal immunity (0·33, 0·18–0·61), compared with trivalent OPVs alone. Given substantial inconsistency and between-trial heterogeneity for serotypes 1 and 3 between direct and indirect effects, researchers only presented pooled estimates on seroconversion, which were at least 80% for serotype 1 and at least 88% for serotype 3 for all vaccine schedules. These findings support prioritizing the addition of one IPV dose for all birth cohorts in WHO's polio eradication program in order to protect against paralysis caused by type 2 poliovirus; however, this inclusion may not lead to prevention of transmission or circulation in areas with the fecal-oral transmission.