There is no cure for polio, but it can be prevented with safe and effective vaccination. Inactivated polio vaccine (IPV) is the only polio vaccine that has been given in the United States (and most developed countries) since 2000. IPV protects against severe disease caused by poliovirus in almost everyone (99 out of 100) who has received all the recommended doses. Two doses of IPV provide at least 90% protection, and three doses provide at least 99% protection. IPV is given by shot in the arm or leg, depending on the person’s age.
Oral polio vaccine (OPV) is used in many developing countries. The CDC recommends that children get four doses of polio vaccine; usually given at each of the following ages: 2 months, 4 months, 6 through 18 months, and 4 through 6 years.
Most adults in the United States were vaccinated as children and are therefore likely to be protected from getting polio. Unless there are specific reasons to believe they were not vaccinated, most adults who were born and raised in the United States can assume they were vaccinated for polio. Polio vaccination has been part of the routine childhood immunization schedule in the United States for decades and is still part of the routine childhood immunization schedule. Adults who received any childhood vaccines in the United States almost certainly were vaccinated for polio.
Adults who know or suspect that they are unvaccinated or incompletely vaccinated against polio should complete their polio vaccination series with IPV. Adults who completed their polio vaccination but who are at increased risk of exposure to poliovirus, such as travel to areas where polio is epidemic or endemic, may receive one lifetime IPV booster (Centers for Disease Control and Prevention, 2024).
Paralytic polio can very rarely happen when certain persons are given OPV (about 1 person out of 750,000 individuals given OPV according to CDC in 1997), especially in persons who are immunocompromised or also in unvaccinated persons who come in contact with the stool of a recently vaccinated child (ex. from changing diapers). In countries where OPV is used that have many unvaccinated/undervaccinated people, AND poor sanitation systems and/or lack of access to clean water, the polioviruses that are normally excreted in the vaccinee’s stool for up to two months after receiving the first dose of OPV can, after circulating in the environment for a time, revert from an inactivated/attenuated virus to one that can again cause paralysis. This is called “variant poliovirus infection” or “circulating vaccine-derived poliovirus infection.” In 2020, there were 1,117 individuals confirmed to have paralytic polio due to circulating vaccine-derived polioviruses (cVDPV) type 1 and type 2. In 2022, an unvaccinated young man in New York State was paralyzed by cVDPVtype2. cVDPV2 was found in several sewage samples, but there were no reports of any other cases.
Because of the emergence of cases of cVDPV2 and the fact that no “wild” poliovirus type 2 had been detected anywhere in the world since 1999 (https://www.who.int), in 2016 type 2 poliovirus was removed from the trivalent OPV making it bivalent and only containing type 1 and type 3 poliovirus. To further address the problem of cVDPV2, a novel OPV2 vaccine was developed and licensed for emergency use. As of September 2023, worldwide approximately 700 million doses have been given in response to outbreaks of cVDPV2 paralysis cases (Bjork, 2023).
References
Bjork, A., Akbar, I. E., Chaudhury, S., Wadood, M. Z., Ather, F., Jorba, J., & Martinez, M. (2023). Progress Toward Poliomyelitis Eradication - Afghanistan, January 2022-June 2023. MMWR. Morbidity and mortality weekly report, 72(38), 1020–1026.
Centers for Disease Control and Prevention (2024, January 6). Polio vaccination. https://www.cdc.gov/vaccines/vpd/polio/index.html.