Health officials have confirmed the second case of measles in suburban Cook County this year — in a 4-year-old, unvaccinated child.

It’s believed that the child caught measles while traveling internationally, according to the Cook County Department of Public Health.

Members of the public may have been exposed if they were in Terminal 5 of O’Hare International Airport between about 7:30 a.m. and 11 a.m. on Sept. 11. Health officials are working to identify and notify people who may have been exposed.

People who were possibly exposed should notify their health care providers if they are unsure about their vaccination status. If they develop symptoms they should talk to their health care providers or a health care facility before going to a medical office or emergency department, so the facility can take steps to prevent other patients and health care providers from being exposed.

A spokesperson for the county health department said the department could not share information about the child’s condition.

Measles is highly contagious and can spread through the air when an infected person breathes, coughs or sneezes. Symptoms can include a rash, high fever, cough, runny nose and red, watery eyes and can appear up to 21 days after a person is exposed.

“Measles is one of the most contagious viruses we know, and it’s entirely preventable,” said Dr. Simbo Ige, commissioner of the Chicago Department of Public Health, in a news release. “This case is a serious reminder that vaccination is not just about individual protection, it’s a critical community responsibility.”

Two doses of the measles, mumps and rubella vaccine are considered 97% protective against the measles, and one dose is considered 93% protective. Children typically receive the first dose of the vaccine, or the similar measles, mumps, rubella and varicella (chickenpox) vaccine at age 12 to 15 months, and the second dose from ages 4 to 6.

The first case in suburban Cook County this year was confirmed in an adult in late April.

It also comes amid continuing debate over the use of vaccines driven by U.S. Department of Health and Human Services Secretary Robert F. Kennedy Jr., who’s overhauled a federal immunization advisory committee that makes recommendations about the use of vaccines. Kennedy was a noted vaccine skeptic before leading HHS.

That advisory committee is scheduled to meet Thursday and Friday and consider recommendations regarding the measles, mumps, rubella and varicella vaccine, among others.

Earlier this year, there were measles outbreaks across the country, with the largest in Texas. The Texas Department of State Health Services announced the end of that outbreak last month.

This year there have been 1,454 confirmed measles cases across the country and three deaths, according to the Centers for Disease Control and Prevention. That’s the most cases since the disease was declared eliminated in the U.S. in 2000, according to a U.S. Measles Tracker hosted by the International Vaccine Access Center at the Johns Hopkins Bloomberg School of Public Health.

People can receive measles vaccines at Cook County Health community health centers by calling 833-308-1988. The Chicago Department of Public Health also offers free measles vaccines at its immunization clinics. Walk-ins are welcome, but people are encouraged to register for appointments at Getvaxchi.chicago.gov.

Health officials recommend people vaccinated before 1968 check with their health care providers about revaccination. People who’ve had only one dose of the vaccine, have a weakened immune system, or who have been exposed in an outbreak should consult a provider about immunization, according to the county health department.

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