A growing measles outbreak has infected more than 600 people across 21 states in 2025, claiming two lives and raising concerns about declining vaccination rates in the United States. Health officials warn that the actual number of cases may be significantly higher due to underreporting.
The outbreak has prompted renewed debate about vaccine efficacy and safety, with U.S. Health and Human Services (HHS) Secretary Robert F. Kennedy Jr. facing criticism for his mixed messaging on vaccines amid the public health crisis.
Outbreak Details and Fatalities
The U.S. Centers for Disease Control and Prevention (CDC) has confirmed over 600 measles cases this year, with the outbreak initially concentrated in Texas, New Mexico, and Oklahoma. The majority of cases involve unvaccinated individuals, particularly children.
Two deaths have been reported in connection with the outbreak. An unvaccinated 8-year-old girl in Texas died from lung failure caused by measles complications. She had no underlying health conditions. The second fatality was an unvaccinated adult who never sought hospital care, raising concerns about how many cases might be going undetected.
Epidemiologist Katelyn Jetelina noted the concerning mortality rate in her blog, The Dose: "We've seen two deaths so far, yet only 228 cases had been reported [at that time]. Measles typically kills 1 in 1,000 unvaccinated individuals. They were either extremely unlucky, or there are more cases than reported."
The CDC has deployed a response team to assist local and state epidemiologists in tracking and containing the outbreak, but investigators report facing resistance to case investigations, further complicating efforts to assess the full scope of the situation.
Vaccine Efficacy and Misinformation
The outbreak has reignited discussions about vaccine efficacy and the spread of misinformation. Two doses of the MMR (measles, mumps, rubella) vaccine are 97% effective at preventing measles infection, according to health authorities.
During a Fox News interview, Secretary Kennedy made controversial statements about vaccine-induced immunity, suggesting that it wanes over time for many people, unlike natural immunity.
Dr. Paul Offit, director of the Vaccine Education Center at Children's Hospital of Philadelphia, refuted this claim, stating that if vaccine-induced immunity waned significantly, measles would not have been declared eliminated in the U.S. in 2000. While antibody levels may decline over time, the immune system retains memory cells that provide long-term protection against the virus.
Dr. Michael Mina, chief scientific officer at telehealth company eMed and an infectious disease expert, emphasized that the current outbreak is primarily driven by unvaccinated individuals. "Even those who may have waning immunity will not transmit large amounts of virus," Mina stated.
Measles Complications vs. Vaccine Safety
Health experts stress that measles can lead to severe complications, especially in children. According to CDC data:
- 1 in 5 unvaccinated people with measles require hospitalization
- 1 in 20 children with measles develop pneumonia
- 1 in 1,000 children with measles develop encephalitis (brain swelling)
- 1 to 3 in 1,000 children with measles die from complications
Kennedy has made claims about the MMR vaccine causing illnesses similar to measles itself, including encephalitis and blindness. However, medical experts strongly dispute these assertions.
"The measles vaccine is incredibly safe," said Dr. Peter Hotez, co-director of the Texas Children's Hospital Center for Vaccine Development and dean of the National School of Tropical Medicine at the Baylor College of Medicine. "This is what anti-vaccine activists do is, they play up and try to scare you with the very, very rare side effects and forget to tell you about the horrific effects of the illness."
A comprehensive study by the CDC and FDA found no evidence linking the MMR vaccine to serious health issues. The most common side effects are mild and temporary, including low-grade fever and occasional rash that typically resolves within 24 to 48 hours.
Kennedy's Controversial Response
Kennedy's response to the outbreak has drawn significant criticism from medical professionals and lawmakers. After attending the funeral of the 8-year-old Texas girl who died from measles, Kennedy posted on social media that "the most effective way to prevent the spread of measles is the M.M.R. vaccine" – a statement that appears to contradict his previous skepticism about vaccines.
Senator Bill Cassidy of Louisiana, a physician who voted to confirm Kennedy, urged him and other top health officials to address the outbreak more decisively: "Everyone should be vaccinated! There is no treatment for measles. No benefit to getting measles. Top health officials should say so unequivocally before another child dies."
Adding to the controversy, Kennedy has ordered a re-examination of the long-debunked claim that vaccines cause autism, with the study to be conducted by a known vaccine skeptic.
Dr. Offit described Kennedy's response to the outbreak as "abysmal," citing his history of criticizing vaccines and minimizing measles' risks. "The disease has returned because a critical percentage have chosen not to vaccinate their children, in large part because of misinformation provided by people like RFK Jr.," Offit said.
Public Health Implications
The current outbreak threatens the United States' status of having eliminated measles, which was declared in 2000 after more than a year had passed without continuous disease transmission.
Health officials continue to emphasize the importance of vaccination according to the recommended schedule: the first MMR dose at 12-15 months of age and the second between 4 and 6 years. Older children, teenagers, and adults who haven't been fully vaccinated should receive one or two doses at least 28 days apart.
As the outbreak continues to spread, public health experts warn that misinformation and declining trust in medical institutions could further complicate containment efforts. Front-line epidemiologists report resistance to case investigations, making it difficult to get an accurate picture of the outbreak's true extent.
The CDC continues to monitor the situation closely, with particular concern for communities with low vaccination rates that remain vulnerable to rapid disease spread.
