Polio Vaccines: Present and Future

Abstract

The history of polio vaccines and their use illustrates the concept of evolution of vaccines driven by changing epidemiological and socioeconomic conditions. The development of two vaccines against poliomyelitis – inactivated Salk vaccine (IPV) and live oral Sabin vaccine (OPV) – is among the most consequential achievements of prophylactic medicine of the past century. Each with their own strengths and weaknesses, they were used over the past 50 years in different settings and different regimens and combinations. This resulted in virtual elimination of the disease in almost the entire world with the exception of a few countries. Continuation of the eradication campaign coordinated by WHO may soon result in complete cessation of wild poliovirus transmission, and poliovirus may join smallpox virus in the club of extinct pathogens. However, unlike smallpox vaccination that was stopped after the interruption of virus circulation, vaccination against poliomyelitis will have to continue into the foreseeable future, due to significant differences in the nature and epidemiology of the viruses. This review provides the reasons for the need to maintain high population immunity against polioviruses, makes the case for developing a new generation of polio vaccines, and discusses their desirable properties as well as new vaccine technologies that could be used to create polio vaccines for the post-eradication environment.