Some Florida counties to test wastewater for polio after it surfaces in other states

Pinellas is one of the five Florida counties with the lowest child vaccination rates for polio.
The polio vaccine became widely available starting in 1955.
The polio vaccine became widely available starting in 1955. [ DREAMSTIME | Dreamstime ]
Published Aug. 21, 2022

FORT LAUDERDALE — For the first time since the U.S. declared polio officially eradicated in 1979, Floridians are concerned about their odds of getting the disease.

Florida is beginning the groundwork to learn if polio is in the state after one person was diagnosed with paralytic polio in Rockland County, New York, and the disease was discovered in New York City’s wastewater.

With this new concern, counties throughout the state are gearing up to test their wastewater and encourage more vaccination. This comes as Florida’s childhood vaccination rate in 2021 dropped to its lowest level in seven years. Pediatricians say the pandemic led to children falling behind on their vaccinations and many still haven’t caught up.

According to state immunization records, nearly 14,000 children started kindergarten in 2021 without being fully immunized. In addition, 2-year-old routine vaccination rates at county-run facilities plummeted from 92.1% in 2019 to 79.3% in 2021.

Florida pediatricians say vaccinations have picked up this fall, but still lag behind where they should be.

An increasing number of families are falling victim to misinformation and choosing not to vaccinate their kids at all, said Dr. Kenneth Alexander, chief of infectious diseases at Nemours Children’s Health in Orlando.

“Increasing vaccine hesitancy is now a global phenomenon,” Alexander said.

The 2022 U.S. Poliovirus Response Team said in its newly issued report that anyone who is unvaccinated is at risk for paralytic disease. They are encouraging everyone — adults and children — to get up to date on their polio shots.

Related: Polio detected in NYC's sewage, suggesting virus circulating

“Even a single case of paralytic polio represents a public health emergency in the United States,” researchers wrote in an Aug. 16 Morbidity and Mortality Weekly Report

The polio vaccine is a four-shot sequence: Babies get three doses and a fourth is given to children between 4 and 6.

Who is at risk?

Anyone in the U.S. is vulnerable at this time if they are unvaccinated or only partially vaccinated.

With polio surfacing again, older Floridians, unsure when or whether they were vaccinated, are concerned that they could be at risk. The vaccine became widely available starting in 1955. Doctors say anyone who received a polio vaccine even decades ago likely still has immunity.

“Most people in this country who have gone to public schools have had to have gotten the polio vaccine,” said Dr. Aldo Calvo, medical director of the ambulatory division at Broward Health. Most states have laws that require children entering child care or public schools to be immunized for polio, diphtheria and tetanus. Florida is one of those states.

However, if you are unvaccinated as an adult, you can still get a three-dose series to gain protection. And, if you are at higher risk of exposure to poliovirus, you can get a lifetime booster dose.

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For those who are unsure of their vaccination status, Calvo recommends testing your titers — the presence of an antibody — through a blood sample to check for immunity to polio.

How polio resurfaced

There are two types of polio vaccine: oral, which is a weakened live virus given through drops, and inactivated, which is administered by injection and uses a killed poliovirus. The U.S. uses the inactivated/injected form. Other countries use the oral type, which is easier to administer and less costly. However, on rare occasions, the weakened virus reverts to a more dangerous form.

Vaccine-derived virus is what has been found in recent polio cases in New York, London and Jerusalem. In the United Kingdom and the United States, health officials believe the virus was imported from someone vaccinated with the live vaccine. The case of paralytic polio in Rockland County is an unvaccinated 20-year-old male who hadn’t traveled but had been at a large gathering with people who had.

It’s possible to get polio and not know it. About 70% of people experience no symptoms at all, and about 25% will experience mild symptoms like fever, headache, stomach pain, fatigue and nausea. Only a small portion get severe symptoms like paralysis.

Most at risk are people who associate primarily with other unvaccinated people, such as parents who home-school their kids together. People who live in pockets of Florida with low vaccination rates are also at risk, particularly those near urban centers.

“Parents have this idea that they’re going to hide away in the herd. That if everybody else vaccinates, they don’t have to,” said Alexander of Nemours. “[But] there really isn’t herd immunity because they’re not dispersed through the community.”

In Rockland County, where the New York case emerged, the polio vaccination rate for children 2 and under is about 60%.

The World Health Organization notes on its website that communities need a vaccination rate of 80% or more to stop polio spread.

Only 75% to 80% of 2-year-olds in Brevard, Osceola, Duval, Orange and Pinellas were completely immunized against vaccine-preventable diseases in 2020, according to the Florida Department of Health. They are the five Florida counties with the lowest child vaccination rates.

“It’s not just polio. Every vaccine-preventable disease has the potential to resurge if we don’t get our vaccination rates where they should be,” said Vincent Hsu, an AdventHealth Orlando epidemiologist and infection control officer.

Florida pediatricians say they are playing catch-up with some children who delayed vaccinations during the COVID-19 pandemic. “There are specific algorithms for how to catch up on vaccine with regards to spacing and combining,” said Calvo of Broward Health, which has held pediatric immunization clinics for children in the last few weeks. “We have a large international community and some children have not been able to receive certain vaccines.”

Calvo said just like international travel brought polio to New York, it could do the same in Florida. “The world is small and we travel readily. Sometimes people can transmit diseases unknowingly. That’s why vaccines are important. We don’t want anyone to suffer from a disease that could have been preventable.”

Dr. Mobeen Rathore, a pediatrician and co-chairperson of the Florida Chapter of the American Academy of Pediatrics’ Emerging Infections Task Force, said he would like to see more children in Florida catching up on shots.

“Many childhood diseases we used to see in the past are resurfacing,” said Rathore. “Polio is just one of those because it still exists in other parts of the world. The only way to be fully protected is to get children fully immunized.”

Is polio coming to Florida?

Some counties and cities are scrambling to test their wastewater.

Altamonte Springs City Manager Frank Martz said the molecular lab used by the city, GT Molecular, will finish developing a polio test within the next 30 days; the city currently tests wastewater in parts of Orange and Seminole counties for COVID-19 and monkeypox.

COVID-19 testing since 2020 gave early warning of both the delta and omicron surges.

Hsu, of AdventHealth, said it’s possible that polio could already be circulating in some parts of Florida. It could have gone undetected since the U.S. no longer routinely monitors for the virus.

Cities with a lot of international travelers are most at risk, he added.

“We don’t know what we don’t know,” Hsu said.

Related: Before the coronavirus, here’s how Tampa Bay fought polio with vaccines

Miami-Dade County also is considering testing its wastewater for polio as soon as the technology to do so becomes available.

In New York’s Rockland and Orange counties, about 8% of the sample taken of wastewater yielded positive poliovirus test results, representing only the second community transmission of poliovirus in the U.S. since 1979.

“I suspect it’s already in many, many places in the U.S.” virologist Vincent Racaniellow of the Columbia University School of Medicine told Time. “In fact, I think that if we look in every major city in the U.S., we will find vaccine-derived polio in the sewage for sure.”

The surveillance of wastewater gives public health officials the chance to detect the 99% of polio cases that don’t show any symptoms but still exist in a community.

“It is possible people in Florida have it and will shed it in their stools,” Rathore said. “Everyone who gets infected doesn’t get paralytic polio, however, if you are not protected, you are at risk.”