PHILADELPHIA—After 42 days with no new cases identified, the Philadelphia Department of Public Health has declared the December 2023/January 2024 measles outbreak to be over. A total of eight Philadelphians, and one person outside of Philadelphia, tested positive for measles during this outbreak. Six of the Philadelphia cases were hospitalized, but all were ultimately discharged home. Six of the cases were children and two were adults.

Measles is a highly infectious virus that can cause serious consequences for people who fall ill with it. However, due to the 93% of Philadelphians who are up-to-date on their MMR vaccine, the outbreak did not spread further.

“In the past, Philadelphia has suffered from extensive measles outbreaks,” said the Health Department’s Director of Disease Control, Dr. Landrus Burress. “Thanks to quick work by our staff and collaboration with healthcare and childcare systems throughout the region, we were able to keep this outbreak small and quickly resolved. I am grateful to the hundreds of thousands of Philadelphians who have safely gotten their routine MMR vaccination, you helped keep us safe.”

In response to the outbreak, the Health Department held a series of free vaccine clinics to allow Philadelphia residents, including children, to catch up on their MMR vaccine schedule. MMR vaccine — which protects against measles, mumps, and rubella — is extremely safe and effective at preventing measles. MMR vaccine has been safely used for decades and protects millions of Americans. Two doses of vaccine are 97% effective at preventing measles. People who have received two doses of vaccine and are not severely immune-compromised are very unlikely to get measles. It is strongly recommended that everyone in Philadelphia talk with their healthcare provider to find out if they need to catch up on their MMR vaccine schedule. MMR vaccine is available at many healthcare provider offices and pharmacies.

As part of the City’s response to the measles outbreak, the Health Department maintained a blog post with the latest information on measles.