Polio isn't endemic in the US. Polio is only still endemic in Pakistan and Afghanistan. Not sure if it was a case from travel or not.
Sequencing indicated it was vaccine-derived poliovirus type 2 (cVDPV2), which would indicate it came from a transmission chain of someone vaccinated with the oral polio vaccine, which isn't used in the US. So it may have come from abroad.
No need for alarm. Most adults are fully vaccinated against polio and it is generally expected to have lifetime immunity. For partially vaccinated children severity is greatly reduced, but parents should ensure their kids are up to date.
Most cases of polio are asymptomatic or mild. A rare subset of cases are paralytic. Vaccination is extremely effective at preventing poliomyelitis. Since most cases aren't paralytic, this may not be the only case in that area, so contact tracing and sequencing will be essential to understand the transmission chain.
Rockland county will be doing a vaccination campaign to get unvaccinated individuals vaccinated. This county was also a site of a large measles outbreak in 2018 in a Hasidic community.
This is just another reminder of the importance of vaccination. Herd immunity is what keeps these viruses at bay. Our vaccination rates have declined in recent years with the rise of vaccine hesitancy and anti-vaxxers. Polio vaccination ideally should be at least 85-90% for herd immunity, but some communities in the US are below that.
We've seen increased global circulation of polio recently. Ukraine had a polio outbreak last year, the country's first since 2015. The Russian invasion disrupted their vaccination campaign. Africa has also had some cases. London recently detected polio virus in its sewage, indicating some silent transmission.
Vaccine-derived is exactly as it sounds. The oral polio vaccine is a live attenuated virus vaccine. However it can rarely mutate and gain back its virulence especially in low vaccination areas with poor sanitation.
The inactivated polio vaccine doesn't have this issue and is generally the preferred vaccine. The US no longer uses the OPV. However, the OPV is much easier to administer since it is oral versus a shot, and is much more effective at preventing transmission than the IPV. So often it is used in developing countries with circulating polio virus to vaccinate.
Sometimes a hybrid vaccination strategy is used where the OPV is used to control transmission, but IPV is used to complete the series and reduce severity.
During large outbreaks, sometimes all young children will be vaccinated to stop the outbreak. Especially if previous vaccination status is unclear in low resource areas.
Some adults at high risk for polio exposure may get a booster such as researchers that handle the virus in the lab, but generally it isn't necessary for fully vaccinated adults.
