Since the United States' first case of polio in almost a decade was reported in New York in July, health officials have worked to encourage polio vaccination in areas with low coverage since "[e]ven a single case of paralytic polio represents a public health emergency."

How vaccination campaigns for kids worked in the past–and why they’re so hard to make effective today.

Polio has likely been circulating in the US longer than previously believed

In July, New York health officials announced that a case of polio had been detected in the state after a young adult from Rockland County became paralyzed from the disease. This was the first reported case of polio in the United States since 2013.

Since then, wastewater surveillance has detected several other samples of poliovirus in Rockland and Orange Counties, as well as New York City. A recent CDC analysis of New York wastewater data found changes in the virus's genome that suggest it may have been circulating around the world for up to a year, with the earliest detected sample from New York being from April.

According to several health experts, polio has likely been circulating in the United States for much longer and more widely than previously believed.

"I think you're gonna see over the next weeks more and more reports of poliovirus in wastewater elsewhere," said Vincent Racaniello, a virologist at Columbia University.

Davida Smyth, from Texas A&M University-San Antonio, agreed, saying she is "absolutely convinced" that poliovirus will be detected in wastewater from other U.S. communities in the coming weeks.

"Here's the thing: polio is here in the U.S. It's not gone," Racaniello said. "It's in the wastewater. It could contaminate you, so if you're not vaccinated, that could be a problem."

How health officials can improve polio vaccination rates

In a recent report, CDC wrote that "[e]ven a single case of paralytic polio represents a public health emergency in the United States." To curtail the potential spread of poliovirus, both federal and local health officials have encouraged people who are unvaccinated to get their polio shots as soon as possible.

Currently, many of the polio samples detected in New York have been from counties with relatively low polio vaccination rates. In both Rockland and Orange Counties where poliovirus was detected, the polio vaccination rate is around 60%, and CDC found that coverage was "as low as 37.3%" in some zip-code specific areas of Rockland County.

Without an effective vaccination campaign, health officials are concerned that poliovirus could spread from New York to other nearby communities, particularly as more people travel.

"Rockland County is basically New York City," said Perry Halkitis, dean of the School of Public Health at Rutgers University. "New York City is basically New Jersey. Rockland County is basically Connecticut."

"Are there probably dozens, if not hundreds, if not more cases of undetected polio in our population? Probably," he added. "Are we catching them? Probably not."

To address vaccine hesitancy in areas with low polio vaccination rates, Mona Montal, chief of staff of the town of Rampo in Rockland County, and Shoshana Bernstein, an independent health communicator, have worked with trusted community leaders to spread the word about polio vaccination. In addition, they created a carefully worded infographic in four different languages, including English, Spanish, Haitian Creole, and Yiddish, to reach more communities.

"People have had PTSD with the word vaccination," Montal said. "So we're immunizing, we're not vaccinating. And that's the messaging."

Separately, Sallie Permar, pediatrician-in-chief at NewYork-Presbyterian Komansky Children's Hospital and chair of the department of pediatrics at Weill Cornell Medicine, and Jay Varma, the director of Weill Cornell's Center for Pandemic Prevention Response, explained in STAT how the United States could improve its vaccine delivery through pediatricians, including by:

• Funding partnerships between local health departments and pediatricians' offices to identify children who are not up to date on their vaccinations
• Making high vaccination rates a part of pediatricians' quality improvement processes, similar to models used for flu vaccines during their seasonal rollouts
• Offering substantial incentive payments through state Medicaid programs to pediatricians who reach high vaccination rates

According to William Schaffner from the Vanderbilt University Medical Center, the reports of polio in the United States are a reminder to health care providers and their patients that the virus continues to be a real health concern.

"[It's] the reverse of the old saying, 'it's gone, but not forgotten,'" Schnaffer said. "Polio is forgotten, but it's not gone." (DePeau-Wilson, MedPage Today, 8/25; Daniel, "Shots," NPR, 8/24; Permar/Varma, STAT, 8/26)