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A worldwide shift in polio vaccines for routine immunisation

Friday, 11th of December 2015 Print

In the second half of April, all tOPV users will switch to bOPV.

A worldwide shift in polio vaccines for routine immunisation

Julie R Garon, Walter A Orenstein

Published Online: 17  2015

DOI: http://dx.doi.org/10.1016/S0140-6736(15)00243-3

 

The Volume 386, No. 10011, p2375–2377, 12 December 2015 Comment

 

Publication History

Published Online: 17 September 2015

© 2015 Elsevier Ltd. All rights reserved.

The world is now closer to global polio eradication than ever before. In 1988, when the World Health Assembly set its sights on complete eradication of polio, an estimated 350 000 paralytic cases occurred and 125 countries were considered endemic. In 2015, only 39 cases have been detected in two countries (as of Sept 8, 2015).1 At present, only wild poliovirus type 1 is known to be circulating. The last outbreak of naturally occurring type 2 wild poliovirus occurred in 1999, and type 3 wild poliovirus has not been detected since 2012. As naturally occurring poliovirus cases decrease, paralysis induced by vaccine-related viruses in oral poliovirus vaccine (OPV) such as vaccine-associated paralytic poliomyelitis (VAPP) and circulating vaccine-derived polioviruses (cVDPV)2 continue to occur, although in small numbers. Thus, for the world to be truly free from polio, all three wild poliovirus serotypes must be eradicated and use of OPV must stop.

The Polio Eradication and Endgame Strategic Plan 2013–20183 outlines the key steps involved in this effort. All countries are expected to introduce at least one dose of inactivated poliovirus vaccine (IPV) into routine immunisation schedules by the end of 2015.4, 5 In April, 2016, countries will change the type of oral vaccine used in routine immunisation through a synchronised worldwide switch from trivalent OPV (tOPV), containing all three serotypes, to bivalent OPV (bOPV), containing only serotypes 1 and 3. Eventually, all use of OPV will be stopped after types 1 and 3 are certified as eradicated worldwide. Although type 2 poliovirus is no longer a naturally occurring threat, the type 2 component of OPV has caused 683 cases of cVDPV since 2000 and 26–31% of the estimated 300–500 annual VAPP cases.6, 7

A comprehensive containment plan for type 2 polioviruses is underway to destroy any remaining viruses (from laboratories, research, or manufacturing facilities) or ensure that they are not released in the community. In 2002–03, escape of a laboratory strain of type 2 poliovirus caused an outbreak in northern India.8 Therefore, trivalent IPV will be administered at age 14 weeks to: reduce risks associated with cessation of the type 2 component of OPV in the tOPV-to-bOPV switch; enable interruption of transmission with use of monovalent OPV2 if outbreaks do occur; and further boost immunity to types 1 and 3, accelerating eradication efforts.4 The speed of IPV introduction and the global synchronisation of the tOPV-to-bOPV switch is an unprecedented effort in immunisation history.

Roland Sutter and colleagues9 randomised controlled trial published in The Lancet provides important data for seroconversion and priming in the recommended bOPV and IPV schedule. Addition of one dose of IPV to a bOPV schedule provides excellent immunogenicity to poliovirus types 1 and 3. Immunogenicity against type 3 is improved with bOPV and one dose of IPV compared with the standard four-dose tOPV schedule, starting at birth. Further, results of the study show that a single dose of IPV induces seroconversion against poliovirus type 2 in 69% of bOPV recipients, and almost all of those who do not seroconvert are primed, as measured by induction of antibody within 7 days of a second dose of IPV. Whether children who are primed are protected against developing polio is unclear, but if type 2 viruses were reintroduced, protective immunity could be reached more quickly in an outbreak response vaccination effort than if type 2 vaccines were used in a wholly naive population. Duration of immunity after one or two doses of IPV was not assessed, and remains an important question.

Several milestones in the polio eradication effort have now been reached: four of six WHO regions are certified free from wild poliovirus, and more than 1 year has passed since a wild poliovirus case was last detected in Africa (suggesting that the fifth WHO region might be on its way to certification).10, 11 Certification requires absence of detected wild polioviruses for 3 years of surveillance that meets WHO standards. With the world detecting the fewest poliovirus cases in history, timing has never been better for a shift in strategy and a change in the vaccines used in routine immunisation schedules worldwide.

The biggest risk factor for cVDPV emergence is low population immunity and accumulation of susceptible people, especially those susceptible to type 2 poliovirus.12 Although risk is minimal, circumstances encountered during the tOPV-to-bOPV switch might lead to increased risk of cVDPV outbreaks and circulation if some areas continue to use tOPV while others do not. Thus, stopping use of all tOPV worldwide within a 2 week period is crucial. The present landscape of continually decreasing cases, strong global stewardship, and country-level political will provides a unique opportunity for the world to eradicate polio (both wild and vaccine-associated viruses) forever. The combination of IPV and OPV is the key to ensuring a polio-free world for future generations.

We declare no competing interests.

References

  1. Global Polio Eradication Initiative. Wild poliovirus list. http://www.polioeradication.org/Dataandmonitoring/Poliothisweek/Wildpolioviruslist.aspx. ((accessed Sept 10, 2015).)
  2. WHO. Vaccine-associated paralytic polio (VAPP) and vaccine-derived poliovirus (VDPV). http://www.who.int/immunization/diseases/poliomyelitis/endgame_objective2/oral_polio_vaccine/VAPPandcVDPVFactSheet-Feb2015.pdf?ua=1; February, 2015. ((accessed Aug 24, 2015).)
  3. Global Polio Eradication Initiative. Polio Eradication and Endgame Strategic Plan 2013–2018. http://www.polioeradication.org/Portals/0/Document/Resources/StrategyWork/PEESP_EN_US.pdf; 2013. ((accessed Aug 24, 2015).)
  4. WHO. Polio vaccines: WHO position paper. Wkly Epidemiol Rec. 2014; 89: 73–92
  5. WHO. Status on country planning for IPV introduction. IPV introduction, OPV withdrawal and routine immunization strengthening. http://www.who.int/immunization/diseases/poliomyelitis/endgame_objective2/en/. ((accessed Aug 25, 2015).)
  6. Platt, LR, Estívariz, CF, and Sutter, RW. Vaccine-associated paralytic poliomyelitis: a review of the epidemiology and estimation of the global burden. J Infect Dis. 2014; 210: S380–S389
  7. Patel, M, Zipursky, S, Orenstein, W, Garon, J, and Zaffran, M. Polio endgame: the global introduction of inactivated polio vaccine. Expert Rev Vaccines. 2015; 14: 749–762
  8. Deshpande, JM, Nadkarni, SS, and Siddiqui, ZA. Detection of MEF-1 laboratory reference strain of poliovirus type 2 in children with poliomyelitis in India in 2002 & 2003. Indian J Med Res. 2003; 118: 217–223
  9. Sutter, RS, Bahl, S, Deshpande, JM et al. Immunogenicity of a new routine vaccination schedule for global poliomyelitis prevention: an open-label, randomised controlled trial. Lancet. 2015; (published online Sept 18.)http://dx.doi.org/10.1016/S0140-6736(15)00237-8.
  10. SEARO. WHO South-East Asia Region certified polio-free. http://www.searo.who.int/mediacentre/releases/2014/pr1569/en/; March 27, 2014. ((accessed Aug 25, 2015).)
  11. Global Polio Eradication Initiative. Is Africa polio-free?. http://www.polioeradication.org/mediaroom/newsstories/Is-Africa-polio-free-/tabid/526/news/1264/Default.aspx; Aug 11, 2015. ((accessed Aug 25, 2015).)
  12. WHO. Cessation of routine oral polio vaccine (OPV) use after global polio eradication. Framework for national policy makers in OPV-using countries (WHO/POLIO/05.02). World Health Organization, Geneva; 2005
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