Characterization of outbreak response strategies and potential vaccine stockpile needs for the polio endgame

BMC Infectious Diseases

Table 3 Impact of outbreak response choices on effective mOPV exportations, new iVDPV excretors, and OPV restarts

Outbreak response choice or assumption	Number of affected iterations	mOPV exportations (totals from 100 iterations)			PID patients infected with OPV used during oSIAs (totals from 100 iterations)				OPV restarts	Expected paralytic cases 2013–2052 (after OPV cessation)^a
Outbreak response choice or assumption	Number of affected iterations	Potential expor-tations	Effective reintro-ductions (to other blocks)	Out-breaks	Newly infected long-term excretors	Potential iVDPV reintro-ductions	Effective iVDPV reintro-ductions	Out-breaks	OPV restarts	No OPV restart	OPV restart	All
Base case	N/A	3,618	312 (14)	0	117	96	22	10	2	340	720,000	15,000
Duration of mOPV use after homotypic OPV cessation (years)
- 3	77	3,141	255 (11)	0	84	57	15	7	10^b	240	850,000	85,000
- through T_end	30	4,153	364 (18)	0	136	119	23	19	0	370	-	370
Minimum R₀ to trigger block-wide response
- 8	45	5,709	479 (23)	0	173	151	34	16	2^b	370	610,000	13,000
- 13	43	1,323	155 (12)	1	64	66	15	7	4	370	1,000,000	40,000
Response delay (days)^c
- Always 30	96	3,521	300 (15)	0	106	99	23	10	2	240	530,000	11,000
- Always 45	92	3,620	311 (14)	0	117	96	22	10	3	620	1,000,000	29,000
- Always 60	96	3,936	335 (18)	0	133	106	23	10	6	640	1,100,000	64,000
oSIA vaccine between OPV2 and OPV13 cessation for serotype 2 outbreaks
- tOPV	36	3,634	315 (5)	0	117	96	21	10	2	340	720,000	15,000
- IPV	36	3,586	317 (14)	1	121	96	22	11	3	360	740,000	22,000
Finite mOPV stockpile	27	3,962	347 (19)	0	166	102	24	10	7^b	1,300	770,000	55,000

Abbreviations: IPV inactivated poliovirus vaccine, iVDPV immunodeficiency-associated vaccine-derived poliovirus; mOPV, monovalent OPV, OPV oral poliovirus vaccine, OPV## cessation globally-coordinated cessation of OPV containing the serotype(s) indicated by ##, oSIA outbreak response supplemental immunization activity, PID primary immunodeficiency disease, R ₀ basic reproduction number, T _end end of the analytical time horizon (i.e., December 31, 2052), tOPV trivalent OPV
^aDoes not include a total of approximately 1,000 expected WPV, VAPP, and cVDPV cases that occur before OPV cessation of each serotype [2]
^bOne additional iteration had ongoing LPV transmission at T_end without having accumulated 50,000 cases since 2016
^cAll alternative choices assume non-adaptive surveillance quality (detection threshold) and response delay in the event of a subpopulation-specific response

ISSN: 1471-2334