Polio is back — how worried should Americans be?


New York’s governor has declared a state of emergency after health officials detected poliovirus in wastewater from five counties, evidence that the disease is circulating. The statement also follows a report by the US Centers for Disease Control and Prevention this summer that an unvaccinated person in Rockland County, New York, was diagnosed with paralytic polio, the first case identified in the US in nearly a decade.

Obviously, these events have raised many questions: Why is a case of polio worrying officials? What does finding poliovirus in wastewater mean? Who should worry about getting the disease? If someone had the vaccine years ago, are they protected now?

To learn more about this disease that most people living today have never experienced, I spoke with CNN medical analyst Dr. Leana Wen, an emergency physician and professor of health policy and management at the George Washington University Milken Institute School of Public Health. He is also the author of “Lifelines: A Doctor’s Journey in the Fight for Public Health.”

CNN: So far, there has only been one documented case of polio-related paralysis in New York. Why does one case concern health officials?

Dr. AS Leana Wen: An August CDC report said that “even a single case of paralytic polio represents a public health emergency in the United States.” This is for two main reasons.

First of all, poliomyelitis is a disease that can have very serious consequences. At its peak in the 1940s and 1950s, polio paralyzed tens of thousands of children each year. Thousands died from the virus.

This changed with the introduction of highly effective vaccines, more than 99% effective in protecting against paralytic poliomyelitis. Thanks to mass vaccination campaigns, the last incidence of wild polio occurred in 1979, and it was thought to have been eradicated in the United States. The reappearance of this disease, which can have serious consequences, is a great threat.

Second, a single case of paralytic polio may be the tip of a large iceberg. Most cases of polio infection are asymptomatic and do not cause paralysis. Symptoms – which can include fatigue, fever and diarrhea – are usually mild and can resemble other viruses. Public health officials are concerned that there are many other people who may be infected with polio and may unknowingly transmit it.

This is particularly worrisome because Rockland County, where the last paralytic case of the virus was diagnosed, has a polio vaccination rate of just 60%. In some parts of the region, the vaccination rate is 37%. These numbers are well below the threshold required for herd immunity, which means that there are many people in the field who are vulnerable to polio infection and potentially serious outcomes.

CNN: What does the detection of poliovirus in wastewater from five counties, including New York City, mean?

Wen: Finding poliovirus in sewage means one of two things: there are people who are actively infected with polio who are shedding the virus, or the sign of the virus may be from people who have recently received the oral polio vaccine (OPV). OPV-2000 is no longer issued in the US. Since 2010, the version used in the US is the inactivated polio vaccine (IPV), which is injected – but other countries are still using OPV, and travelers from those places may be thrown away. vaccine virus

Wastewater samples are taken from a Queens College lab on August 25 in New York City.

In rare circumstances, the weakened virus from people who have recently received OPV can cause paralytic poliomyelitis in unvaccinated people, which is the main reason that OPV is no longer used in the US.

An additional concern is that a wastewater sample from Nassau County on Long Island has been genetically linked to a case of paralytic polio identified in Rockland County. (The two counties are not adjacent, but roughly 40 miles apart.) This is further evidence of the community’s expansion, which has gone largely unnoticed.

CNN: How can people contract polio?

Wen: Polio is an infectious disease that can be transmitted in many ways. A major route is fecal-oral, meaning someone can get polio if they come into contact with the feces of an infected person. This could happen, especially in children, by putting objects such as toys contaminated with faeces into their mouths.

Poliovirus can also be transmitted through the respiratory tract; for example, if someone who is infected coughs or sneezes and those droplets land around your mouth. It’s worth noting that vaccinated people can also get polio and pass it on to others, even if they’re perfectly protected against serious disease.

CNN: Should New Yorkers be worried about contracting polio?

Wen: Again, people with the polio vaccine are very well protected from polio and should not worry at this time. It should be noted, however, that while IPV is very good at preventing the worst potential effects of the disease, people who received the vaccine can be carriers of polio and can transmit it to others. Those at risk for serious outcomes are unvaccinated and incompletely vaccinated individuals, including children under 6 years of age who have not yet completed their polio vaccine series.

CNN: How many polio vaccines should someone get?

Wen: The CDC recommends that children receive four doses of IPV. The first is given at 2 months, the second at 4 months, the third between 6 and 18 months and the fourth between 4 and 6 years.

Adults who have never received the polio vaccine should receive three doses of IPV. The first should be given as soon as possible, the second two months later and the third six to 12 months after the second.

CNN: If someone had the vaccine years ago, are they still protected? Who should get a polio booster now?

Wen: Protection against serious disease remains strong for many years after immunization; it is thought to probably last a lifetime. Most vaccine recipients do not need to receive additional doses.

However, if someone has not completed their original vaccine series, they should receive the remaining doses. Some fully vaccinated people may also receive an additional lifetime boost of IPV in specific circumstances, such as if they are in direct contact with someone suspected of having polio or are health care workers at increased risk of exposure to people with the disease.

CNN: What if you’re not sure if you were vaccinated? Say you don’t remember getting the vaccine, and it’s been years. Is there a blood test you can do to confirm this in any way?

Wen: You can check with your primary care doctor’s office or state health department to see if they have records of your immunizations. If they don’t, and you have no other way to verify (for example, by asking your parents or other relatives or caregivers), you should talk to your health care provider about getting the full polio vaccine series. There is no blood test that can reliably detect whether you are fully vaccinated against polio.

CNN: What if you or your family members have not yet received the polio vaccine?

Wen: People who have not yet received a dose or are not fully vaccinated should ensure that they receive the full series of polio vaccines immediately. This is especially important if they live in or around Rockland County, New York, but really everyone should be caught up on their regular immunizations.

It was a tragedy decades ago that so many children became permanently paralyzed and even died from polio. This should not happen again, as we have effective vaccines that can prevent the serious consequences of the disease.