U.S. measles cases till March surpasses all of 2024

Measles outbreak in the U.S. with 378 cases, 2 deaths, and concerns over vaccine effectiveness and spread.

Since the first measles case was reported on January 23, 2025 in Texas, the number of cases has risen sharply and the virus has spread to New York City and 17 other States in the U.S. As of March 20, the total number of cases reported across the U.S. stands at 378, with Texas and New Mexico alone reporting 327 and 43 cases, respectively. There have been two deaths so far and both were in unvaccinated individuals. With 301 cases reported as of March 14, the total number of cases reported in less than two months since the first case was reported this year surpassed 285 cases reported for all of 2024.

The first outbreak of measles in the U.S. this year has been in the Mennonite community in Gaines County, West Texas. So far about 226 cases have been reported from Gaines County, and many have been tied to a Mennonite community with low vaccine uptake. The Mennonite community is largely unvaccinated due to cultural and historical reasons. The Mennonite community in Gaines County has reported nearly 14% vaccine exemption rates for school-aged children.

Of the 378 confirmed measles cases reported as of March 20, CDC noted that 124 (33%)  cases have been in children aged under five years and 159 (42%) cases have been in individuals aged 5-19 years; in Texas, 63 adults have been infected. As expected, 95% of individuals infected with measles are either unvaccinated or with unknown vaccination status. While 3% of individuals infected with measles have taken only one dose of the MMR vaccine, 2% have taken both doses of the MMR vaccine.

That 2% individuals got infected with measles despite being fully vaccinated is not unexpected — even two doses of the MMR vaccine does not provide 100% protection. According to the CDC, one dose of the MMR vaccine is 93% effective against measles, while the effectiveness increases to 97% with two doses. “Some [fully] vaccinated people may still get measles, mumps, or rubella if they are exposed to the viruses. It could be that their immune system didn’t respond as well as they should have to the vaccine; their immune system’s ability to fight the infection decreased over time; or they have prolonged, close contact with someone who has a virus,” the CDC says. However, fully vaccinated people generally have milder disease symptoms and are also less likely to spread the virus to others. But almost everyone who has not been vaccinated will get infected if they are exposed to the virus and get sick.

Though the MMR vaccine is primarily meant to prevent measles infection, individuals exposed to measles virus can still take the vaccine. The MMR vaccine can offer some degree of protection against the disease or reduce the severity of illness if vaccinated within 72 hours of exposure to the measles virus.

On March 13, the WHO said that 1,27,350 measles cases were reported in 2024 in the European region (53 countries in Europe and central Asia), double the number of cases reported in 2023 and the highest number since 1997. There were 38 deaths as of March 6, 2025, the WHO said. The European region accounted for a third of all measles cases globally in 2024.