Recently, public health officials announced a case of paralytic polio in a young adult northwest of New York City—the first reported instance of polio in the US since 2013. Poliovirus recently has been detected in wastewater samples in New York. The patient was unvaccinated and had not traveled to a country where polio is a risk. DNA testing suggested that the virus had been circulating locally under the radar for up to a year.
Infection with the polio virus primarily infects the intestinal tract, is often asymptomatic, and only about 25% of the time causes a flu-like illness. Depending on the virus type, 1% to 5% of people with infections will develop meningitis. About 0.5% to 0.05% of those who are infected—1 in 200 to 1 in 2000 individuals—will develop paralysis after the virus infects the spinal cord, and according to the CDC, a small proportion of them will die as a result of breathing problems,.
Based on these numbers, a paralytic case is a red flag that tells you there could be 100 people or more in the community who are not showing symptoms. Indeed, a similar polio virus has now been detected in several wastewater samples in the state and in city sewage, providing additional evidence of community circulation.
“The detection of the polio virus in wastewater samples in New York City is alarming, but not surprising,” New York State Health Commissioner said in a recent statement. “Already, the State Health Department—working with local and federal partners—is responding urgently, continuing case investigation and aggressively assessing spread.”
It’s also not surprising that the paralytic case occurred in an unvaccinated individual who lives in an area with a low polio vaccination rate, meaning that it could potentially spread like wildfire in a small, consolidated group that has a significant percentage of unvaccinated people.
As of this August, 2022, only about 60% of 2-year-olds in Rockland County had had the recommended 3 doses of the inactivated poliovirus vaccine, with the rate as low as about 37% in one area. That compares with a New York statewide average of about 79% and a national average of almost 93% for infants born in 2017 and 2018.
Because state and national vaccination rates are high, a general outbreak is unlikely. Although one patient does not mean a pandemic, we do have to be concerned about it, so there isn’t a second, third, and hundredth patient.. Local outbreaks could happen anywhere, especially among pockets of unvaccinated people. Generally, only unvaccinated or incompletely vaccinated individuals are at risk of symptomatic polio. And because there are no antiviral or other treatments for polio, vaccination is the key to preventing the disease. You just don’t see cases in people who have been vaccinated. If polio infection is suspected. The CDC has a worksheet for submitting suspected samples for confirmation.
Although 2 types of polio vaccines are in use around the world, since 2000, the US has exclusively administered IPV, which is greater than 99% effective after the recommended 3 doses. IPV uses killed wild-type poliovirus to induce what’s believed to be lifelong immunity in the bloodstream. Because it is inactivated, IPV cannot cause poliovirus infection.
Oral polio vaccine (OPV), which previously was used in the US and is still administered in many other countries, is about 95% effective after 3 doses. It uses a weakened poliovirus strain to induce immunity in the digestive tract and is also thought to provide lifelong protection. In rare instances, the weakened virus in OPV regains its ability to infect the nervous system. This results in symptomatic polio in about 1 in 3 million vaccine recipients. The reverted virus also is excreted and passed on from person to person, which possibly was the source of the New York paralytic polio case.
Although poliovirus infections in the US currently are rare and have not been identified outside New York State, risk factors vary regionally, so it’s prudent to be aware of any local risk or signs of the disease. State and local health departments generally issue warnings to health care professionals, as New York State did recently. In partnership with the CDC, health departments operate a nationwide disease surveillance network. Physicians are required to report suspected paralytic polio cases to health departments within 4 hours and suspected nonparalytic polio cases within 1 day.
State and local health agencies also work with the CDC to conduct wastewater surveillance for certain viruses such as SARS-CoV-2. Wastewater sampling for polio virus was initiated in New York after the paralytic case was reported.
Although wastewater surveillance is helpful, it may be incomplete and given the ease of travel, any area may be at risk. It is very sad to see at this point, after highly successful pandemic control, that a vaccine-preventable disease reappears because of lack of vaccination. Everyone should be aware of his/her own vaccination history—not just those living where the virus has been detected. Most people who are at risk of exposure and are not up to date with polio vaccines should be immunized, which includes infants and older children; adults of all ages; and pregnant people.
In addition to reviewing vaccine histories during visits. State immunization information systems and school records are sources of vaccination records. These systems consolidate vaccination data regardless of where they were administered. Even so, they may not be complete. But it’s a safe bet that anyone who went to public schools in the US in the past 70 years has been vaccinated. But if there is any question of this, offering the polio vaccine—either as a booster or a full 3-dose course—is a low-risk way to make sure one is protected. Thus when in doubt, vaccinate. For those who are not vaccinated or are incompletely vaccinated, a first dose should be given immediately, if possible.. Follow-up doses should then be scheduled accordingly.
The CDC guidance includes specific schedules for children, adults, and people vaccinated in other countries with a bivalent OPV, which does not protect against type 2 poliovirus. Accelerated schedules are included for those planning travel to areas where polio is endemic, as are catch-up dose recommendations for incompletely immunized individuals.
The CDC recommends 1 lifetime booster shot for adults who have had 3 doses of IPV and are at high risk of polio exposure. This includes people who are traveling to areas where the virus is epidemic or endemic, laboratory technicians who handle polio virus specimens, and health care workers and others caring for infected people..
With vaccine hesitancy on the rise, addressing it is essential to protect against polio and other vaccine-preventable diseases. Individuals’ reasons for hesitancy and the strength of their resistance varies and must be addressed Some people believe vaccines are no longer necessary while others lack trust in the health care system. Some merely have concerns about vaccines and can be persuaded, while others are adamantly opposed to them. Everyone should be made aware of the toll infectious diseases took before current vaccines were available. One eye-opening statistic: in the early 1950s about 15 000 paralytic polio cases occurred annually in the US. Convincing hesitant parents to have their children vaccinated is of paramount importance. A great teaching opportunity is to say to the parents of unvaccinated children, “Do you want your child to risk polio with paralysis when it can easily and safely be prevented with a series of vaccinations?”
Although few of us need to fear a possible recurrence of this dreadful disease, knowledge, as imparted above, is a powerful means of preventing a recurrent pandemic!