Measles cases rising in U.S. Here’s what to know if you live in Connecticut

CT Insider – Wednesday, March 12, 2025
By Jordan Nathaniel Fenster

There has been a national spotlight on the measles in recent weeks, as it spreads, perhaps farther and faster than it has at any point in decades in the United States.

There have been no known cases in Connecticut in 2025 and, largely, the disease has not stretched beyond one, or so, cases in the state in most years. But there is at least reason to pay attention as doctors and health experts track an outbreak in western rural Texas and New Mexico where there have been a combined few hundred cases.

“I would argue it’s the most contagious disease in existence,” Scott Roberts, an infectious disease specialist at Yale-New Haven Hospital, said.

The basic reproduction number, called an R-naught, is about 18, which means that for every one person infected, 18 can expect to get the disease. Roberts said, “that’s the highest R-naught I know of.”

“It’s very contagious,” said Ulysses Wu, head of infection prevention at Hartford HealthCare. “The problem with the contagiousness is that you’re contagious five days before and five days after the rash.”

Before the advent of the measles vaccine in 1963, measles caused 2.6 million deaths each year, according to the World Health Organization. In 2023, an estimated 107,500 people, mostly children 5 years old and younger, died from the disease globally, because the vaccine was not available to them.

Yet measles was all but conquered in this country. There have been small, isolated outbreaks, but they were localized, contained by widespread vaccination, with a particularly large outbreak in the late 1980s and early 1990s. That’s changed.

There have been 222 confirmed cases so far this year in the United States, according to the U.S. Centers for Disease Control and Prevention as of March 6. Those cases were as close to Connecticut as New York City and Rhode Island, about as many as there were in the entirety of 2024.

Of those 222 cases, 17 percent ended up in the hospital and two people have died – the first two deaths in about a decade in this country.

“I call it the zombie disease because it’s back from the dead,” Wu said.

But, “In Connecticut, we have a 97.7 percent vaccination rate, though that’s probably decreasing,” Wu said. Nationally, it’s somewhat lower, 92.7 percent, based on CDC data.

The measles vaccination rate is 87 percent in Minnesota, and not much higher in Ohio, Missouri, Oklahoma and other states.

The vaccine is 97 percent effective at preventing infection, according to the CDC.

“It’s safe,” Wu said of the vaccine, though, “there are certain patient populations you have to be very careful giving it to, such as the immunocompromised.”

“Let’s state for the record: it doesn’t cause autism,” he said.

Despite Connecticut’s high vaccination rate, some people might consider getting a measles booster, Roberts said. For the most part, the vaccine confers life-long protection, though if a person is not sure of their vaccination status, Roberts suggests getting a booster.

“Another scenario is outbreak settings,” he said. “If there was an measles outbreak in Stamford, they would issue guidance that some people may want an additional booster dose at that time.”

In addition, there was a period of time between 1957 and 1968, during which a different sort of vaccine, a non-live vaccine, was used to prevent measles.

“That didn’t work,” Roberts said. “If people received that outdated vaccine, they should also get boosted.”

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