Ontario County is the latest county to report measles cases, adding two related infections involving unvaccinated residents as public health officials across the region respond to a growing number of confirmed and suspected cases.
At least 13 confirmed cases have now been reported across Ontario, Steuben and Seneca counties based on the latest local updates: two in Ontario County, six in Steuben County and five in Seneca County. Seneca County officials have also reported dozens of other likely illnesses, while the available information doesn’t establish whether the investigations in the three counties are connected.
Ontario County Public Health learned of its two positive results Aug. 31. Officials said both residents isolated safely at home during the period when they could have exposed others, and the county hasn’t released additional information about them to protect their privacy.
The new Ontario County cases come after a steady increase in Steuben County and an outbreak designation in Seneca County, broadening what had initially appeared to be more localized measles activity into a regional public health concern.
Health officials across all three counties continue to stress that measles is extremely contagious, but the risk remains substantially lower for people who are fully vaccinated. The infections reported in the region have been concentrated among unvaccinated residents, and officials are encouraging anyone unsure of their immunity to contact a health care provider.
The cases are also emerging just as new Cornell University research raises questions about how communities measure measles vulnerability. Researchers found that apparently strong countywide vaccination rates can obscure individual schools or other smaller communities where significantly more people remain susceptible to infection.
Ontario County becomes latest to report cases
Ontario County’s announcement Monday marked the newest confirmed development in the region.
The two related cases involve unvaccinated residents, though the county said the overall risk to the public remains low, particularly for people who are fully vaccinated.
“Most people in Ontario County are vaccinated and are not at risk of getting measles,” Public Health Director Kate Ott said. “If unsure of your vaccine status, contact your healthcare provider.”
Ontario County officials specifically warned that unvaccinated people, infants younger than 12 months, pregnant people and people who are immunocompromised can face greater risk.
People who develop a fever, cough, runny nose, red and watery eyes or a rash are being advised to isolate and wear a mask. Anyone planning to seek care at a doctor’s office, urgent care center or emergency department should call ahead so staff can prepare for a possible measles patient.
Steuben County reaches six confirmed cases
Steuben County Public Health learned of the newest positive results Aug. 29 and 30. One resident began experiencing symptoms Aug. 23 and was subsequently considered no longer contagious. The second developed symptoms Aug. 28 and remained isolated at home when the latest update was released. Both of the newest patients were unvaccinated.
County officials haven’t disclosed how those two residents became infected or whether their cases are linked to the four infections that had already been confirmed.
Potential public exposure locations were identified, but health officials said they weren’t releasing the locations because doing so could compromise patient privacy. Instead, the county has been working with the state Department of Health and local health care providers to identify and directly contact people known to have been exposed.
The six cases represent a rapid increase from the four previously reported in Steuben County and have prompted expanded contact tracing and repeated warnings for residents to verify whether they’re immune.
Seneca County meets outbreak definition
Seneca County’s situation has gone beyond a handful of isolated confirmed infections.
Public Health Director Scott King said five confirmed cases and dozens of other likely illnesses meet New York’s definition of a measles outbreak. Two of the five confirmed patients had been hospitalized when the county’s latest reported figures were released.
King said transmission was occurring primarily among unvaccinated residents.
Seneca County health workers have increased home visits to administer the measles, mumps and rubella vaccine, but King said the contagious nature of measles has made it difficult for officials to get ahead of transmission.
Despite the outbreak designation and suspected additional illnesses, county officials have continued to characterize the overall risk to the broader public as low, particularly for people who are fully vaccinated or were born before 1957 and are presumed to have immunity from previous infection.
Vaccination averages may not show where risk is concentrated
Cornell researchers recently assembled vaccination records covering roughly 50,000 schools, 13,000 school districts and 3,000 counties across 45 states and Washington, D.C., to examine how measles risk is distributed.
Their conclusion was that county averages can be misleading.
A county vaccination rate near the roughly 95% level generally associated with broad community protection can still include individual schools where considerably larger concentrations of students are unvaccinated or have received only one of the two recommended MMR doses. Those smaller pockets can provide enough susceptible people for measles to continue spreading after a case is introduced.
The researchers found that the national share of students considered unprotected roughly doubled after the COVID-19 pandemic, increasing from about 5% to nearly 10%. They attributed the decline to multiple factors, including vaccine hesitancy, misinformation and differences in state exemption policies.
That doesn’t mean every school with lower vaccination coverage will experience an outbreak. Rather, the research suggests officials may need to look below countywide averages when identifying communities where one imported or newly introduced case could lead to wider transmission.
The distinction is particularly relevant in the Finger Lakes now that multiple counties are managing cases at the same time.
What residents should watch for
Early measles symptoms generally appear seven to 14 days after exposure and can include a high fever, cough, runny nose and red or watery eyes. A red, blotchy rash usually follows several days later, commonly beginning around the face and hairline before spreading downward.
Health officials are asking anyone who knows or believes they’ve been exposed to monitor for symptoms for 21 days.
People who develop possible measles symptoms shouldn’t walk unannounced into a doctor’s office, urgent care center or hospital emergency department. Officials recommend calling first and explaining the possible measles exposure so staff can prepare to isolate the patient and reduce the chance of exposing people in waiting rooms or other areas.
That precaution matters because measles spreads through the air and is considered extremely contagious.
The disease can also lead to serious complications. Ontario County Public Health warned that measles can cause pneumonia, encephalitis — inflammation of the brain — and lasting neurological damage. The county said an estimated one to three people die for every 1,000 measles cases.
Vaccination and treatment after exposure
Health officials generally consider someone immune if they have documentation of two MMR vaccine doses, were born before 1957 or have had immunity confirmed through blood testing.
Two doses of the MMR vaccine are about 97% effective at preventing measles, according to Seneca County health officials.
For people who aren’t vaccinated and have recently been exposed, timing can matter.
Steuben County officials said an MMR vaccination administered within 72 hours of exposure may provide protection, while immune globulin may be an option within six days for some people. Unvaccinated residents, pregnant people and people who are immunocompromised are being urged to contact a medical provider or their county health department promptly after a known or suspected exposure.
The regional investigations remain active, meaning the current tally may not represent the final extent of transmission. Ontario County is now investigating its first two reported infections, Steuben County is continuing contact tracing around six confirmed cases and Seneca County has already described its cases as an outbreak.
For residents, the guidance across all three counties is largely the same: Know your vaccination status, watch for symptoms after possible exposure, stay home if symptoms develop and call ahead before seeking in-person medical care.
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