Planning for globally coordinated cessation of bivalent oral poliovirus vaccine: risks of non-synchronous cessation and unauthorized oral poliovirus vaccine use

Table 2 Annual bOPV SIA frequencies between the tOPV-bOPV switch and bOPV cessation assumed for the different population immunity maintenance scenarios, adopted from prior work [29] for the analysis of the vulnerability of populations in the event of non-synchronous bOPV cessation

Subpopulation characteristics		Annual number of bOPV SIAs for each population immunity maintenance scenario
Routine immunization coverage with 3 or more non-birth bOPV doses	Basic reproduction number (for serotype 1 wild poliovirus)	Base case (continued high population immunity maintenance)	Medium population immunity maintenance	Low population immunity maintenance^a
5% or 10%	Any	6	4	3
30%	Any	5	3	2
60%	10 or less	3	1	1
60%	More than 10	5	3	1
90%	Any	1	1	0
98%	10 or less	0	0	0
98%	More than 10	1	0	0

^a Previous research indicates that this scenario results in a circulating vaccine-derived poliovirus outbreak after bOPV cessation [29].
bOPV bivalent oral poliovirus vaccine, tOPV trivalent oral poliovirus vaccine, SIA supplemental immunization activity

ISSN: 1471-2334