Year: 2020
Type: editorial
Abstract: As the vaccine of choice for the Global Polio Eradication Initiative (GPEI), oral poliovirus vaccine (OPV) is inexpensive, easy to administer, and can provide good protection against poliomyelitis and poliovirus infection, through durable humoral immunity and induction of intestinal mucosal immunity.Even though trivalent OPV is a safe and effective vaccine and has a remarkable disease elimination record, all 3 strains are live attenuated RNA viruses capable of genetic mutation during replication.This means that polioviruses in OPV can undergo genetic changes in vaccine recipients to reverse attenuation.This inherent in-stability represents a key disadvantage of OPV that is manifest in some of the current polio eradication challenges.It has long been known that sporadic cases of vaccine-associated paralytic polio (VAPP) occur in recently vaccinated individuals (recipient VAPP) and in susceptible persons indirectly exposed to vaccine virus, such as close contacts of persons recently vaccinated or community contacts (contact VAPP).The global burden of VAPP was estimated in 2011 to be approximately 250-500 cases per year [1].In countries using OPV, of the 3 poliovirus vaccine serotypes, type 3 is the predominant serotype isolated from the stool of recipient and contact VAPP cases, followed by type 2 and then type 1 [1,2].The higher frequency of type 2 and type 3 VAPP may be related to the fewer nucleotide substitutions responsible for the attenuated phenotype in types 2 and 3 virus strains, making reversion easier [2].As global eradication progressed in the decade following the World Health Assembly declaration of the global eradication goal in 1988, many countries achieved the elimination of all 3 types of indigenous wild polioviruses, including many in the developing world.However, these newly polio-free countries were now completely dependent on vaccination to maintain immunity against polio in the population.The continued use of OPV with low coverage led to a widening immunity gap and revealed another manifestation of the genetic in-stability of the polioviruses in OPV.In this case, instead of OPV-related polio being restricted to vaccine recipients and contacts, the vaccine virus continues to transmit from
Authors: Stephen L Cochi, Mark A Pallansch
Language: English
Subfield: Infectious Diseases
Field: Medicine
Domain: Health Sciences
Open Access status: hybrid
Estimated APC paid: $4,763
Award: G7543494365
OpenAlex ID: W3039863063