Impact of inactivated poliovirus vaccine on mucosal immunity: implications for the polio eradication endgame

Figures & data

Figure 1. Map of global inactivated poliovirus vaccine use and planned dates for its introduction. Data source: WHO/IVB Database, as of 1 May 2015. Map production: Immunization Vaccines and Biologicals (IVB), WHO.

Table 1. Effects of different vaccination strategies on humoral and mucosal immunity to poliovirus types 1, 2 and 3, and the risk of vaccine-associated paralytic poliomyelitis and type 2 circulating vaccine-derived poliovirus emergence.

	Humoral immunity			Mucosal immunity			VAPP risk	Risk of type 2 cVDPV emergence^†
	PV1	PV2	PV3	PV1	PV2	PV3
Routine immunization
IPV–IPV–IPV	+++	+++	+++	–	–	–	–	–
tOPV–tOPV–tOPV	+++	+++	+++	+++	+++	+++	+	+
bOPV–bOPV–bOPV	+++	?^‡	+++	+++	?^‡	+++	+	–
tOPV–tOPV–tOPV+IPV	+++	+++	+++	+++	+++	+++	+	+
IPV–tOPV–tOPV	+++	+++	+++	+++	+++	+++	–	+
bOPV–bOPV–bOPV+IPV	+++	?^‡	+++	+++	?^‡	+++	+	–
IPV–bOPV–bOPV	+++	?^‡	+++	+++	?^‡	+++	–	–
Supplementary immunization activities
tOPV	+++	+++	+++	+++	+++	+++	+	+
bOPV	+++	?^‡	+++	+++	?^‡	+++	+	–
IPV (low tOPV routine immunization coverage)	+++	+++	+++	+	+	+	–	–
IPV (high tOPV routine immunization coverage)	+++	+++	+++	+++	+++	+++	–	–

–: Absent or negligible; +: Low; ++: Moderate; +++: Strong; bOPV: Bivalent oral poliovirus vaccine; cVDPV: Circulating vaccine-derived poliovirus; IPV: Inactivated poliovirus vaccine; PV1: Type 1 poliovirus; PV2: Type 2 poliovirus; PV3: Type 3 poliovirus; tOPV: Trivalent oral poliovirus vaccine; VAPP: Vaccine-associated paralytic poliomyelitis.

^†Refers to the likelihood of a Sabin type 2 virus regaining neurovirulence and transmissibility. Any vaccination strategy involving the administration of type 2 Sabin strains (such as those including tOPV) will carry a risk of type 2 cVDPV emergence.

^‡There may be some heterotypic immunity among the poliovirus strains. The extent of this immunity remains equivocal, but is likely to be short-lived and of limited significance [55–57].

Figure 2. Schematic representation of serum and secretory antibody responses following administration of IPV to OPV- or IPV-primed individuals. Primary immunization with OPV induces both a humoral response (serum IgG) and a mucosal response (intestinal and nasopharyngeal IgA), whereas IPV induces only a humoral response and potentially a limited mucosal response in the nasopharynx. However, following the waning of OPV-induced mucosal immunity, administration of IPV is capable of boosting both humoral and mucosal immunity in OPV-primed individuals. The same boosting of humoral immunity does not occur among individuals without prior OPV exposure.

Status update on country planning for IPV introduction. WHO. Available from: www.who.int/entity/immunization/diseases/poliomyelitis/endgame_objective2/IPVmap_2015_May.pptx?ua=1 [Last accessed 14 May 2015]

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