Apr 04, 2020 Volume 39 5Number 10230 p1089-1166, e62-e63
The case for replacing live oral polio vaccine with inactivated vaccine in the Americas
Jorge A Alfaro-Murillo, et al
Before the development of the inactivated poliovirus vaccine (IPV) and live oral poliovirus vaccine (OPV), sporadic outbreaks of poliomyelitis were reported to cause as many as 18 000 cases of paralysis and over 3000 deaths in the USA alone.1 The straightforward oral administration, high effectiveness, and relatively low cost of OPV was fundamental to the substantial reduction in polio achieved by mass vaccination campaigns. Wild polioviruses were certified by WHO to be eliminated throughout the Americas in 1994 . However, an adverse effect of OPV is vaccine-associated paralytic polio. Among the countries exclusively using OPV in 2012, an estimated 400 cases of vaccine-associated paralytic polio occurred that year.2 This burden is more than double the incidence of wild polio in 2019. 3 Vaccine-derived polioviruses (VDPV) can also spread from person to person, a process that led to more than 250 additional cases of paralysis during 2019. 4 The risk of paralytic polio associated with OPV spurred many countries to switch to the safer IPV. While IPV elicits a much weaker mucosal immune response than OPV, 5 and is thus less effective at averting transmission, it is very protective against disease. In the Americas, Canada transitioned to exclusive IPV use in 1995, the USA in 2000, Costa Rica in 2010, and Uruguay in 2012. However, the remaining 31 countries in the Americas ( appendix) continue to administer at least one dose of OPV.