Outbreaks of polio caused regular panic decades ago, until a vaccine was developed and the disease was largely eradicated. Then on Friday, New York City health officials announced they had found the virus in sewage samples, suggesting that polio was likely circulating in the city again.
Parents of young children wondered, perhaps for the first time in their lives and, collectively, for the first time in generations, how much they should worry about polio.
Anabela Borges, a designer who lives in Brooklyn’s Crown Heights neighborhood, said she had friends whose children were probably not vaccinated. After Friday’s announcement, he said he planned to “make his friends aware.”
Ms. Borges said she hoped her 7-month-old daughter, Ava, who is old enough to have received three of the four shots recommended for children, was far enough along in the regimen to be protected. “Polio is really dangerous for babies like her,” Mrs. Borges said as she and her daughter’s nanny took Ava for a walk in her stroller.
In New York City, the overall polio vaccination rate among children 5 years and younger is 86%, and most adults in the United States were vaccinated against polio as children. Still, in some city zip codes, fewer than two-thirds of children 5 and younger have received at least three doses, a number that worries health officials.
The state Department of Health said in a statement that the discovery of the virus underscored “the urgency for all adults and children in New York to be immunized, especially those in the New York metropolitan area.”
The announcement came three weeks after a man in Rockland County, N.Y., north of the city, was diagnosed with a case of polio that left him paralyzed. Officials now say polio has been circulating in the county’s wastewater since May.
“The risk to New Yorkers is real, but the defense is so simple: get vaccinated against polio,” said Dr. Ashwin Vasan, New York City’s health commissioner, in a statement. “With polio circulating in our communities, there is simply nothing more essential than vaccinating our children to protect them from this virus, and if you are an unvaccinated or incompletely vaccinated adult, choose now to get vaccinated.” .
The spread of the virus poses a risk to unvaccinated people, but three doses of the current vaccine provide at least 99 percent protection against serious disease. Children too young to be fully vaccinated are also vulnerable, as are children whose parents have refused or delayed vaccination.
Health officials fear that the detection of polio in New York City sewage may precede other cases of paralytic polio.
The fight against polio
The highly contagious virus was one of the most feared diseases until the 1950s, when the first vaccine was developed.
“In the absence of a relatively massive vaccination campaign, I think it’s very likely that it will be one or more cases” in the city, said Dr. Jay Varma, an epidemiologist and former deputy city health commissioner.
The citywide vaccination rate declined amid the pandemic as visits to pediatricians were postponed and the spread of vaccine misinformation accelerated. Even before the arrival of Covid, vaccination rates for a number of preventable viruses in some neighborhoods were low enough to worry health officials.
Although effective in preventing paralysis, the vaccine used in the United States in recent decades is less effective in limiting transmission. People who have been vaccinated can still carry and excrete the virus, even if they do not experience infection or symptoms.
That, epidemiologists say, may mean the virus will be difficult to eradicate quickly, further underscoring why vaccination is so critical for protection, a state Health Department spokeswoman said.
Many people who become infected with polio do not have symptoms, but some people will have a fever or nausea. Dr. Bernard Camins, an infectious disease specialist and medical director of infection prevention at the Mount Sinai Health System, urged doctors to be on the lookout for these symptoms and to consider ordering polio tests for patients who do not they are fully vaccinated.
About 4 percent of those who contract the virus develop viral meningitis, and about 1 in 200 will become paralyzed, according to health officials.
“The problem,” Dr. Camins said, “is that if you have one case of paralysis, there may be hundreds of others that are not symptomatic or have symptoms that probably won’t be identified as polio.”
The polio virus had previously been found in sewage samples in Rockland and Orange counties, but Friday’s announcement was the first sign of its presence in New York City.
Neither the city nor state health departments provided details on where in the five boroughs the virus had been detected in the sewage. State officials said six “positive samples of concern” had been identified in the city’s wastewater, two collected in June and four in July.
The last case of polio found in the United States before the one in Rockland County was in 2013.
Before polio vaccines were first introduced in the 1950s, the virus was a source of fear, especially during the summer months when outbreaks were most common. Cities closed swimming pools as a prevention tactic, and some parents kept their children indoors.
In 1916, polio killed 6,000 people in the United States and left at least 21,000 more, mostly children, with permanent disabilities. More than a third of the deaths occurred in New York City, where the outbreak delayed the opening of public schools.
An outbreak in 1952 paralyzed more than 20,000 people and left many children with iron lungs. The first effective vaccine emerged soon after, and the virus began to recede.
Today, there are only two countries, Pakistan and Afghanistan, where polio is endemic. It has been kept at bay in the rest of the world thanks to the widespread use of vaccines.
Cases appear beyond these two countries with some regularity, the result of the oral vaccine that is used in much of the world. The oral vaccine uses a weakened but live virus. It’s safe, but a person who gets it can spread the weakened virus to other people. In the United States, only the inactivated polio vaccine has been used since 2000.
The CDC recommends that children receive four doses, with the final injection given between ages 4 and 6.
“What we’re seeing is a wake-up call for people who thought poliovirus was just a problem elsewhere,” said Capt. Derek Ehrhardt, the Centers’ epidemiologist and polio eradication incident manager. for Disease Control and Prevention.
The virus lives primarily in a person’s throat and intestines and is most commonly transmitted through contact with feces.
If the weakened virus used in the oral vaccine circulates widely enough in communities with low vaccination rates or replicates in someone with a compromised immune system, it can mutate into a virulent form that can cause paralysis, according to the CDC.
Outbreaks of this “circulating vaccine-derived poliovirus” have occurred in numerous countries in recent years. Open sewers and contaminated drinking water can help speed the spread.
Health officials believe the polio virus was introduced to New York by someone who received the live virus vaccine in another country, or by an unvaccinated person who contracted vaccine-derived polio abroad .
Officials say the virus detected in the two counties north of New York City is genetically related to the vaccine-derived virus sampled this year in Jerusalem, as well as to sewage samples in London that have resulted in to a renewed polio vaccination campaign there.
On Friday, the CDC had confirmed the presence of poliovirus in 20 sewage samples in Rockland and Orange counties, all of which were genetically linked to the Rockland County resident’s case of paralytic polio. The counties are next to each other.
Of the 20 samples, two were collected in May, three in June, and eight in July from Rockland County; two were collected in June and five in July in Orange County.
Dr. Irina Gelman, Orange County’s health commissioner, said officials assumed each positive sample collected in her county indicated a separate person locally infected with the virus, but added that she was awaiting further genetic analysis from the CDC to be sure
Health officials believe hundreds of people in the area could be infected, he said. The estimate is based on how many people would normally have to have the virus for there to be a single case of paralytic polio, combined with the increase in vaccine-derived polio cases worldwide and very low vaccine coverage in sections from New York.
“Part of me still hopes it won’t be,” he said.
“We’re really working with a kind of perfect storm scenario,” he added. “We have low vaccination rates in Orange County for vaccine-preventable diseases, especially among our pediatric populations.”
The only case of polio that has been confirmed so far was in a 20-year-old ultra-Orthodox Jewish man living in Rockland County, according to several local officials. Orange and Rockland counties are home to large numbers of ultra-Orthodox Jews, and anti-vaccine sentiment has spread among some in that community.
A measles outbreak was also concentrated among people in the ultra-Orthodox community in 2019, although vaccine misinformation and low vaccination rates are also more widespread, Dr. Gelman said.
Vaccination rates in Rockland and Orange counties are far below what is needed to prevent the spread of the virus, according to the state Department of Health. Among 2-year-olds, about 60 percent of children in both counties had all three recommended polio vaccines, state data show, compared with 79 percent statewide.
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