The Legacy of the Polio Vaccine

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In an interview for Think Global Health, an immunization expert discussed the historic importance of the polio vaccine and the continued risk of future polio transmission. Robert F. Kennedy Jr., an anti-vaccine activist and the presumptive nominee for Secretary of Health and Human Services, has previously suggested that the polio vaccine causes cancer and does more harm than good. 

WALTER ORENSTEIN; worenst@emory.edu 

    Orenstein is a professor emeritus at the Emory School of Medicine and former head of the U.S. immunization program at the Centers for Disease Control and Prevention.

In his interview with Think Global Health, Orenstein noted that the World Health Organization began its campaign to eradicate polio in 1988, when the virus caused approximately 350,000 cases of paralytic polio and more than 100 countries were endemic or epidemic for the virus. Today, only two countries have endemic polio: Afghanistan and Pakistan. War and the destruction of infrastructure also increases the risk of transmission; traces of polio were detected in Gaza in July 2024, though it was eradicated from the region 25 years earlier. 

Orenstein told the Institute for Public Accuracy that “the U.S. government needs to invest in surveillance and vaccination efforts across the globe. In low- and middle-income countries in particular, efforts include mass immunization campaigns. If we stop doing those campaigns, we’ll likely build large, susceptible populations. 

“In 1955, before the Salk polio vaccine became available, there were 20,000 cases of paralytic polio every year in the U.S. Polio is a terrible illness. It is very infectious. It invades the nervous system and kills the nerves that tell the muscles what to do. It’s like cutting the wires to a lightbulb; the muscles go flaccid. I was seven years old when the polio vaccine came out. People wanted that vaccine. Polio scared the living daylights out of people. 

“Polio transmission is very difficult to predict, because less than one percent of infections lead to paralysis. But the miracle of the polio vaccine is that we have basically eliminated polio in much of the world. The problem is that as long as the polio virus circulates anywhere, it can infect anywhere. We found that out in Rockland County, New York, in 2022. If we stop vaccinating or reduce our vaccination levels, polio can again become endemic in the U.S. and around the world. Even if you have high overall levels of immunization, if there are clusters of people who are more susceptible and are unvaccinated, those clusters of people can be infected. When someone is vaccinated against polio, they protect themselves and help protect their community. Some people can’t get vaccinated because of compromised immune systems. But they are protected as long as they aren’t exposed.” 

RFK Jr. has also spread a rumor that the polio vaccine causes cancer. Orenstein noted that “early polio vaccines were contaminated with SV40, a carcinogenic ingredient. But the science has shown that there is no increase in cancer in people who received those vaccines [in the 1960s] versus those who did not. That ingredient has not been in vaccines in many years. 

“If we stopped vaccinating today [in the U.S.], we wouldn’t see anything immediately. But we could eventually have major outbreaks. We need to educate the American public––and RFK Jr.––as to how safe and effective the inactivated polio vaccine is.”