(NEW YORK) — About 152 people across 30 counties in West Virginia have been exposed to measles, state health officials said Friday.

Earlier this week, the first confirmed case of measles in the state since 2009 was identified, according to the West Virginia Department of Health (WVDH). The patient was someone who was undervaccinated and had a history of recent international travel, the department said.

State health leaders said that since then, they’ve learned of dozens of exposed individuals including 128 West Virginia residents and 24 out-of-state contacts from four neighboring states.

Of the people who were exposed, 62% don’t have documentation proving they are protected against measles and are considered at risk, according to WVDH.

“The Bureau for Public Health is strongly recommending those exposed individuals with no evidence of immunity against the virus quarantine until May 9 or 10, 2024, depending on their last date of exposure,” the department said in a release.

The WVDH did not immediately reply to ABC News’ request for comment.

The news about the possible exposure comes amid a rapid increase in the number of measles cases during the first quarter of 2024, in part due to several localized outbreaks, including at a children’s hospital and daycare center in Philadelphia, an elementary school in Florida and a migrant center in Chicago.

As of Friday, 128 cases have been reported in 19 states, according to the Centers for Disease Control and Prevention (CDC). More than half of those infected were under 5 years old and 81% are unvaccinated or have unknown vaccination status, the federal health agency said.

Measles is a highly transmissible virus. It’s so infectious that a measles patient could infect up to 90% of close contacts who are not immune, either through prior infection or vaccination, according to the CDC.

The CDC currently recommends that everyone receive two doses of the measles, mumps and rubella (MMR) vaccine, with the first dose between ages 12 and 15 months and the second dose between ages 4 and 6.

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One dose of the measles vaccine is 93% effective at preventing infection if exposed to the virus, and two doses are 97% effective, according to the CDC.

The WVDH said it is working closely with the Monongalia County Health Department, where the positive measles case was identified, to make sure health officials have adequate testing supplies and MMR vaccine availability.

“The Bureau for Public Health recommends the safe and effective MMR vaccination as part of a routine vaccination schedule for all children and adults,” the department said in the release. “With summer travel coming up and people going to and coming from countries that have seen sharp upticks in measles cases, the time is now to be sure you and your family members are up-to-date on their MMR vaccine.”

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