The Centers for Disease Control and Prevention (CDC) recorded 2,065 measles cases across 44 states in 2025, the highest count since the early 1990s. There were 53 new infections reported in the last week of December; most occurred in South Carolina, Arizona and Utah, where there are ongoing outbreaks.
Declining vaccination rates across the U.S. and around the world are likely driving the measles resurgence. As vaccine rates fall and measles outbreaks continue , the U.S. risks losing its measles-free status, as Canada did last year.
What is measles and how serious is it?
Measles is a viral disease that causes fever, cough and a distinct rash. Although it is not a seasonal virus like the flu, officials typically document a surge of cases during periods of high travel such as during the summer and winter holidays.
For most people, measles causes mild illness. Historically, measles infections killed between one and three people per 1,000 infections, in line with current mortality rates. In 2025, just over 10% of all measles patients were hospitalized, and three people died from their infections.
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Although infections are usually mild, the measles virus is one of the most contagious diseases in the world. Around 90% of unvaccinated people who come into contact with the virus become infected, making it about 12 times more infectious than the flu and twice as contagious as COVID-19. The measles virus spreads through airborne droplets and can linger in the air or on surfaces for up to two hours.
How effective is the measles vaccine?
The U.S. first approved a measles vaccine in 1963. Today, the CDC and American Academy of Pediatrics recommend that children receive two doses of the measles vaccine — given as the combination measles, mumps and rubella, or MMR, vaccine.
The vaccine is highly effective: Two doses of the shot provide 97% protection against the virus. The first dose is generally given when children turn 1, meaning infants are particularly vulnerable to the disease. Although young babies do receive antibodies from their mother in utero and in breast milk, infants are at a higher risk of severe complications from the virus, including pneumonia and encephalitis.
In areas with ongoing outbreaks, infants as young as 6 months old can receive the vaccine, though this is considered an extra dose and not a replacement for regular shots.
Still, children are most likely to contract the disease. Last year, 26% of cases were reported in children younger than 5 years old; that population also accounted for 20% of all hospitalizations. Overall, 68% of U.S. measles cases were recorded among people 19 years old, or younger.
There is currently no cure for measles; however, patients or those who may have been exposed to the virus can be treated with antibodies to help the immune system fight off infection.
Why is measles resurging?
Since 1992, U.S. health officials have typically recorded fewer than 100 measles cases per year. In 2000, the U.S. officially declared that it had eliminated measles, meaning that it had prevented consistent spread for an entire year. Infections peaked, however, in 2019 when there were 1,274 confirmed cases. In 2024, there were 285 cases across 16 outbreaks.
Trends in U.S. measles cases mirrored the global burden. The World Health Organization recorded 360,000 cases in 2018 down from 853,000 in 2000. There was a resurgence of infections in 2019 when numbers returned to the same level as the early 2000’s. Measles infections started falling again after the pandemic; in 2024, there were about 475,000 cases worldwide. Cases spiked last year when there were around 11 million infections.
Health officials believe that waning vaccination rates and misinformation campaigns during the COVID-19 pandemic have contributed to a global resurgence. Globally, about 84% of children between 12 and 23 months had received the measles vaccine in 2024, up from 82% in 2021 but just shy of pre-pandemic rates of 86%.
In the U.S., vaccination coverage among kindergartners decreased from 95.2% during the 2019–2020 school year to 92.7% in the 2023–2024 school year. A 95% coverage rate is a typical public health target, as scientists believe this threshold achieves herd immunity, when enough people are immune to a disease that it can no longer spread easily, therefore protecting vaccinated and unvaccinated alike.
More than 90% of people infected in the U.S. in 2025 were not vaccinated against the disease, according to CDC data.
