The Reasons Behind the Poliovirus Vaccine’s Success Poliomyelitis is a highly contagious virus that has paralyzed millions of people throughout the years. Although some cases of polio virus infections still occur (mostly in third-world countries), the mainstream spread of the virus was eradicated in 1988, when 99.9% of annual diagnosed cases were reduced. Now, 80% of the world’s population live in polio-free zones (Our Progress Against Polio, 2014). This vaccine is now considered to be one of the most successful vaccines ever discovered. Currently, there are four different types of polio vaccines: Oral Polio Vaccine (OPV), Monovalent Oral Polio Vaccines (mOPV1 and mOPV3), Bivalent Oral Polio Vaccine (bOPV) and Inactivated Polio Vaccine (IPV) (Inactivated Polio Vaccine, 2014). The OPV vaccine was created to have a unique ability to produce unmatched gastrointestinal immunity, thereby preventing infection with wild-type virus (Jesus, 2007). The OPV is composed of att strains of all three PV serotypes, grown in vitro. When creating the vaccine, scientists were looking for strains that would be able to replicate efficiently in the GI tract and central nervous system, as well as have the genetic stability to survive replication within the human host (Jesus, 2007). However, the temperature sensitive phenotype of the strains is thought to be the most efficient and important part of the vaccine, that lead to this medical phenomena (Jesus, 2007). Thus, the OPV became the preferred polio vaccine in most countries.
The fact that the vaccine was able to produce antibodies that replicated inside the GI and the CNS was revolutionary. By creating this vaccine, the transmission of the wild-type virus was stopped, and therefore, the polio-virus was ultimately beat in most of the world’s population.
