I learned about polio in medical school as a disease of history. When it was at its peak in the 1940s and early 1950s, parents were terrified that their children would be among the tens of thousands every year who became permanently disabled. Thousands of children died when the paralysis immobilized their breathing muscles.
Thanks to highly effective vaccines, cases of polio paralysis fell to below 100 in the 1960s. The last case of wild-type polio that originated in the United States was in 1979. My generation of physicians thought we’d never encounter this disease.
That’s no longer true. Because of low vaccination rates, polio is back and appears to be spreading in at least one part of the country. Other vaccine-preventable diseases will also reemerge unless we take urgent steps to reverse this tragic trend.
In July, an unvaccinated 20-year-old man residing in Rockland County, N.Y., was diagnosed with polio, which resulted in paralysis in his legs. He hadn’t traveled abroad during the presumed exposure period, which means he contracted the virus locally.
Mary T. Bassett, commissioner of the New York State Health Department, said that her agency is “treating the single case of polio as just the tip of the iceberg of much greater potential spread.” This is because most polio infections are mild or asymptomatic. Symptoms, if present, mimic many other viral illnesses. They include fever, fatigue, diarrhea and sore throat. And because polio was believed to be eradicated, clinicians are not looking for it. The one diagnosed case severe enough to cause paralysis raises the concern that there could be dozens — even hundreds — of other infected people who could be unknowingly transmitting the virus to others.
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In addition, poliovirus has been found in wastewater in Rockland County and nearby Orange County, including in a sample taken in April. This suggests spread could have been underway for months. Last week, the virus was also detected in New York City’s sewage.
The good news is that the polio vaccines are at least 99 percent effective at preventing paralytic polio. These vaccines are protective for many years — probably a lifetime. This is what made polio eradication possible; it’s estimated that we reached herd immunity when 80 percent of the population developed immunity. Nationwide, the numbers are good: 92 percent of children have received at least three doses of the polio vaccine by age 2 (the first three doses are given at 2 months, 4 months and between 6 and 18 months; a fourth dose is administered between 4 and 6 years old).
The bad news is that some communities are falling far below the 80 percent threshold. In Rockland County, only 60 percent of 2-year-olds have received their first three vaccine doses as of this month, a decline from 67 percent in July 2020. In some Zip codes, coverage is as low as 37 percent.
There is almost certainly an outbreak of polio in New York that’s spreading among the unvaccinated. This is a public health emergency and should be an urgent call to action across the country for those who are unvaccinated to begin their inoculations now. It’s critical for children to complete their entire four-dose vaccine series. And adults who were never vaccinated should do so to prevent permanent paralysis to themselves as well as to help stop spread to others, including to children who are too young to be fully vaccinated.
The reemergence of polio should also be a much-needed catalyst to reverse the worrisome trends in routine childhood immunizations. According to a report by the Centers for Disease Control and Prevention, national vaccination coverage dropped by an entire percentage point in the 2020-2021 school year compared with the previous year, with an additional 35,000 children entering kindergarten without documentation of completed vaccination against diseases such as measles, chickenpox and diphtheria. Globally, millions of children have missed their immunizations over the past two years, a drop that the United Nations has called the “largest backslide in childhood vaccination in a generation.”
Much of this can be attributed to pandemic-related disruption in health-care services. I also worry about the insidious effect of vaccine disinformation and that backlash to covid restrictions has worsened trust in public health. Moreover, most parents of young children never experienced the terror of polio firsthand and might not appreciate the importance of preventing the disease.
As the United States exits the emergency phase of the pandemic, we must divert resources previously directed to the coronavirus to other neglected areas, especially childhood immunizations. Older people who came of age before polio was eradicated should remind younger generations of how much parents feared, year after year, that their children would be the next ones struck by incurable paralysis or death.
It doesn’t have to be this way. We’ve stopped polio before. We can do it again.