After years with few or no reported measles cases, Connecticut has now confirmed two cases in 2026, including one in a vaccinated adult.
The cases come as the United States experiences its largest measles resurgence in years. But despite the trend, a Yale infectious disease specialist says Connecticut remains well-positioned to avoid the large outbreaks seen elsewhere.
"Anytime there's a measles case, I'm worried about it," said Dr. Scott Roberts, an infectious disease specialist at Yale School of Medicine and associate medical director of infection prevention at Yale New Haven Health. "What's most worrisome is the trend."
"We've gone a number of years without any cases of measles in Connecticut. We had one case last year, now this is the second case this year, “So all signs point to continued cases for the years to come."
Connecticut's vaccination rates provide protection
Roberts said Connecticut's high vaccination rate creates what public health experts call "herd immunity," making it much harder for the virus to spread.
"Over 95% of the population in the state of Connecticut is vaccinated against measles or has some form of immunity," Roberts said. "We have among the highest immunized kindergarten population in the entire country."
That level of immunity matters because measles is among the most contagious viruses known.
"If there is a case, which we've now seen two instances of it this year, my strong suspicion is it would not lead to additional spread," he said. "For the most part, most people, if there is measles in Connecticut, they'll be immune."
The Centers for Disease Control and Prevention says about 95% community immunity is needed to prevent sustained measles outbreaks because the virus spreads so easily through the air.
Why measles is returning
Roberts attributes the resurgence largely to vaccine hesitancy in some parts of the country.
"We're having declining vaccination rates across the country," he said. "The problem with measles is that it's one of the most contagious diseases we know about. It spreads through aerosols, so it's airborne."
"When I think about that, I think about exhaled smoke," Roberts said. "It just kind of lingers in the air, and even if that infected person leaves the room, somebody coming into that room next is theoretically at risk."
States including Texas, Utah and South Carolina have experienced much larger outbreaks after vaccination rates dropped below the threshold needed to prevent widespread transmission.
Why vaccinated people can still get measles
One of Connecticut's recent cases involved a vaccinated adult, but Roberts said that should not undermine confidence in the vaccine.
"Nothing's 100% effective," he said. "The measles vaccine, especially if you receive two doses, it's 97% effective."
Breakthrough infections typically occur after unusually prolonged exposure. In this recent case, he said the adult was likely caring for an infected member of the household and exposed around the clock.
"When you do see vaccine breakthrough cases like this, it's somebody who has a really close contact and a high degree of contact," Roberts said. "The good news is, first, if you do get infected, it's much more mild."
Symptoms can be difficult to recognize
Roberts said measles can be especially challenging to diagnose early because initial symptoms resemble many common viral illnesses.
"As a father of three kids, my kids present with early measles symptoms every week when they bring home something from daycare," he said. "Cough, runny nose, fever—you don't know what it is."
"It's not until they break out with this very characteristic rash that occurs later on in the illness" that measles becomes apparent, he said.
Because of that, Roberts said doctors rely not only on symptoms but also on whether someone has recently traveled to an area experiencing an outbreak or has had known exposure to someone with measles.
Should Connecticut residents be worried?
For vaccinated residents, Roberts said the answer is largely no.
"I do not perceive myself to be at risk of measles exposure right now," he said. "If I go to the grocery store, I'm not worried about being exposed to measles."
Asked whether a vaccinated Connecticut resident should worry about attending a sporting event or another large gathering, Roberts was equally reassuring.
"I would go to that stadium," Roberts said. "I wouldn't be too worried about it right now."
Still, he encouraged residents to verify their vaccination history.
"Now is a great time to double check your vaccine records and verify that you did receive at least one, preferably two doses of the measles vaccine," Roberts said.
"If you don't have that, there's ambiguity, you're not sure, then it's relatively simple and risk-free to just give another measles shot."
