The vaccine-derived polio virus that gave an unvaccinated US resident the first case of paralytic polio in nearly a decade has been genetically linked to spread in two other countries: the United Kingdom and Israel. Now that it has been discovered in the US, health officials fear it has spread to hundreds or even thousands of people in a poorly vaccinated New York county.
On Monday, New York officials urged unvaccinated residents to get vaccinated “as soon as possible” to prevent further spread of the virus.
“Polio is very contagious and a person can transmit the virus even if they are not sick,” the New York State Department of Health said in a news release today. The virus spreads easily through a fecal-oral route due to poor hygiene and sanitation. The virus is transmitted through direct contact with an infected person or contaminated food or water. “Symptoms, which can be mild and flu-like, can take up to 30 days to appear, during which time an infected person can transmit the virus to others,” the health department added.
About one in 200 people infected with poliovirus develop paralysis, according to the U.S. Centers for Disease Control and Prevention. That means that for the one case of paralytic polio that occurred in New York — which was not linked to any international travel — hundreds of others were likely already infected.
Lowering risk
Most Americans have been vaccinated against the polio virus, which protects them against the dangerous virus. The three-dose inactivated polio vaccine (IPV), given in the first 24 months with a fourth dose booster between ages 4 and 6, is part of the CDC’s standard immunization schedule. According to CDC data from 2015, nearly 93 percent of U.S. children received their three doses of IPV by age 2.
But the New York case of paralyzed polio was found in Rockland County, a northern New York City suburb, where vaccination rates are low. In 2019, the province even struggled with an explosive measles outbreak due to the same problem.
According to the state health department, Rockland County currently has a polio vaccination rate of only 60.5 percent among 2-year-olds, compared to the national average of 79 percent.
The paralytic case in Rockland, which occurred in an unvaccinated young adult, was first reported by authorities on July 21, but the person’s symptoms began in June. Since then, transmission has likely continued, with epidemiologists now say thousands could get infected.
Multinational distribution
And that’s only in the US. On Friday, the Global Polio Eradication Initiative (GPEI) announced that the strain of vaccine-derived poliovirus behind the Rockland case — a type 2 VDPV — is genetically linked to viruses detected in wastewater samples in London and Jerusalem, suggesting an ongoing, multinational spread of the dangerous virus.
To be clear, vaccine-derived poliovirus strains originate from oral polio vaccines (OPV), which are no longer used in the US or UK. (Isreal uses both IPV and OPV.) The oral polio vaccines use attenuated viruses that, if allowed to spread from person to person amid poor sanitation and low vaccination rates, can mutate to regain disease-causing abilities. It is unclear where and how this VDPV2 originated and spread.
“It is vital that all countries, especially those with extensive travel and contact with polio-affected countries and areas, strengthen surveillance to quickly detect new virus entry and enable a rapid response,” GPEI said. “Countries, territories and territories must also maintain uniformly high routine vaccination rates at the district and lowest administrative levels to protect children from polio and minimize the effects of a new virus being introduced.”
New York officials are heeding that call, opening vaccination clinics and urging residents to line up for injections, especially children.
“Polio is a dangerous disease with potentially devastating consequences,” New York state health commissioner Mary Bassett said in a statement. “In the United States, we are fortunate to have the critical protection provided by polio vaccination, which has protected our country and New Yorkers for over 60 years. Given how quickly polio can spread, now is the time for every adult, parent, and guardian to get themselves and their children vaccinated as soon as possible.”
