These three things can help stop measles from spreading in hospitals

Key takeaways:

• Measles cases are climbing in the United States, with more than 900 cases reported so far in 2025.
• Early identification, isolation and information sharing can help prevent transmission in health care facilities.

After a child was admitted to Children’s Hospital Los Angeles with measles last summer, three things helped prevent secondary transmission: early identification, isolation and information sharing.

Karyn Wong, MPH, CIC, an infection preventionist at the hospital, described the three “Is” of measles prevention to Healio in a bit more detail:

• early identification of cases and exposures;
• isolating affected individuals; and
• sharing information with hospital staff and local health departments.

 

Derived from Braunfeld J, et al. Contact tracing and prevention of secondary measles transmission in a pediatric acute care hospital — Los Angeles County, July 2024. Presented at: SHEA Spring 2025; April 27-30, 2025; Orlando.

More than 900 confirmed measles cases have been reported in 30 states so far in 2025, including three deaths. Measles is one of the world’s most infectious diseases, and experts say it is imperative to stop transmission as soon as possible.

We talked to Wong at the SHEA Spring conference about how the hospital used the three “Is” method in response to a measles case and what her advice is for health care workers who encounter measles at their hospitals.

According to Wong and colleagues, a vaccinated 12-year-old child presented with a fever, rash, mouth sores and cough in July 2024 after traveling abroad. Once staff suspected the child had measles, they isolated the patient and began identifying people who may have been exposed. The child subsequently tested positive for measles.

“It caused this whole meeting between infection prevention and our hospital leadership in order to see what we would do should this patient turn positive,” Wong said. “There was a lot of background work that was happening as we were waiting for that result to come back — whether it be positive or negative.”

“When that result came back positive, we already had laid some groundwork,” she said.

Infection prevention staff identified 350 people who were exposed, including 187 staff members, 73 patients and 90 visitors. Overall, 257 had been immunized or were presumed to be immune to measles.

Wong said two other hospital staff members — Michael A. Smit, MD, MSPH, hospital epidemiologist and medical director of infection prevention and control, and Susan Wu, MD, chief quality officer — reviewed immunization and medical records for the remaining 93 people who had no known vaccination status. She said anyone who did not know if they were vaccinated were presumed to be unvaccinated and were eligible for post-exposure prophylaxis (PEP).

Wong and colleagues reported that 49 people received PEP at the hospital, and an additional 11 visitors and 11 patients received PEP elsewhere. Most people (n = 39) who received PEP at the hospital got the MMR vaccine; two people received intramuscular immunoglobulin, and eight people received intravenous immunoglobulin, they noted.

Sixteen visitors and patients did not receive PEP, but they monitored their symptoms daily after exposure. Six staff members who did not have immunity isolated themselves at home for 21 days after exposure.

Wong and colleagues reported that no one exposed to the case developed measles.

It was not just hospital staff who were involved in this effort, Wong said. She said staff worked closely with the local health department to identify exposures and offer PEP to people who were eligible.

“They were meeting with us daily in order to assess who was exposed and also determine the next steps,” she said.

Wong said health departments are great resources in infection prevention and that health care workers should reach out to departments if they encounter measles in the workplace. Additionally, she said clinicians can reach out to infection prevention staff in other facilities for assistance.

“We are very supportive, and we are very willing to help,” she said.

“It is prompt identification, early isolation and information sharing that is critical to prevent the spread of measles, and then also to vaccinate,” Wong said. “At the end of the day, vaccinate. Vaccines work, and we know it is proven that this vaccine works.”

References:

• Braunfeld J, et al. Contact tracing and prevention of secondary measles transmission in a pediatric acute care hospital — Los Angeles County, July 2024. Presented at: SHEA Spring 2025; April 27-30, 2025; Orlando.
• CDC. Measles cases and outbreaks. https://www.cdc.gov/measles/data-research/index.html. Updated April 25, 2025. Accessed May 1, 2025.

For more information:

For questions about infection prevention, Karyn Wong, MPH, CIC, can be reached at karwong@chla.usc.edu.

For clinical questions, contact Michael A. Smit, MD, MSPH, at msmit@chla.usc.edu.