Study	Reason for exclusion
Li 2016b	Ineligible intervention: any sequential IPV‐OPV among the four trials summarised in this study
McCollough 1969	Ineligible study design: uncontrolled before and after study
Moǐseieva 2002	Ineligible study design: not a randomised controlled trial
Swartz 1998	Ineligible study design: cohort study
Wattigney 2001	Ineligible study design: less than three points after intervention to be considered as a short interrupted time series
Ye 2018	Ineligible intervention: sequential schedules of IPV made from sabin strain (sIPV) and not from WPVs

IPV‐OPV: sequential inactivated poliovirus vaccine‐oral poliovirus vaccine; sIPV: Sabin IPV; WPV: wild poliovirus.