New York's Recent Polio Case is a Rare Occurrence
When the State of New York recently confirmed an unvaccinated resident was diagnosed with polio, it was the first case of polio in the U.S. since 2013.
Announced on July 21, 2022, the Rockland County, NY, patient reportedly contracted a form of polio that can be traced back to the live, but weakened, poliovirus used in the oral polio vaccine (OPV).
NY health officials said the version of poliovirus affecting the male patient, who has muscle weakness and paralysis, likely originated somewhere overseas, where oral vaccines are still administered.
Following the NY detection, the Global Polio Laboratory Network confirmed on July 29, 2022, that the VDPV2 isolated was genetically linked to two Sabin-like type 2 isolates, related to environmental samples collected in New York, Israel, and London, UK, during June 2022.
This polio vaccine version has not been used in the U.S. since 2000.
With more than 10 billion doses of the OPV administered since 2000, there have been about 800 cases of vaccine-derived polio reported.
The eradication of polio in the Americas has been accomplished solely through the use of the live oral vaccine.
The U.S. CDC has endorsed the inactivated polio vaccine (IPV), which offers nearly complete protection from paralytic polio.
Most children receive the IPV at 2, 4, and 6 months of age.
William Petri, the chair of the WHO's Polio Research Committee, explained to The Conversation on July 22, 2022, what vaccine-derived poliovirus is and why the IPV vaccine can't cause it.
The weakened form of the live virus in the oral vaccine cannot cause disease.
However, because the vaccine is given orally, the weakened virus is excreted in the feces and can spread from someone vaccinated.
If the weakened virus circulates person to person for long enough, it can mutate and regain its ability to cause paralysis.
The mutated virus can then infect people in communities with poor sanitation and low vaccination rates, causing disease and even paralysis.
This is an exceedingly rare occurrence.
However, as a precaution, Israel vaccinated about five million children in April 2022.
The good news is a safer oral polio vaccine engineered not to mutate is now replacing the earlier live-virus vaccine in targeted countries.
Approximately 370 million doses of nOPV2 have been administered across 21 countries under its WHO Emergency Use Listing to date.
To alert international travelers of their polio risks, the CDC stated on July 27, 2022, 'before any international travel to Africa, Asia, or Eastern Europe, anyone unvaccinated, incompletely vaccinated, or with an unknown polio vaccination status should complete the routine polio vaccine series.'
Other polio vaccination news is posted at Vax-Before-Travel.com/Polio.
Note: This article is republished from The Conversation under a Creative Commons license. And was manually curated for mobile readership.