United States— The United States may soon see measles becoming common again, 25 years after it was declared eliminated, experts warned on Thursday.

Researchers say that if childhood vaccination rates stay the same, measles could spread regularly, with around 851,300 cases expected in the next 25 years. If vaccination rates drop by just 10%, there could be as many as 11.1 million cases.

Measles hasn’t spread continuously in the US since the year 2000. But recently, very few children have been getting the MMR (measles, mumps, rubella) vaccine, which has led to more outbreaks. So far, in 2025, there have been at least 800 measles cases in the US, including a major outbreak in Texas that caused 624 cases and 2 deaths, according to the Centers for Disease Control and Prevention (CDC).

This year’s total measles cases are already 180% higher than the total number of cases reported in 2024. Most of the cases are among unvaccinated people or people with unknown vaccination status. The current outbreak is mainly affecting closely connected communities with low vaccination rates.

Dr. Nathan Lo from Stanford Medical School said that if childhood vaccinations dropped by 50%, the US could see 51.2 million measles cases, 9.9 million rubella cases, 4.3 million polio cases, and over 159,000 deaths in the next 25 years. This would also result in millions of hospitalizations and long-term health problems, like brain damage from measles, birth defects from rubella, and paralysis from polio.

The good news? Just a small increase of 5% in vaccination rates could prevent measles from coming back. Other vaccine-preventable diseases are not likely to become widespread again — unless vaccination rates drop sharply. For example, if rates fall by 35%, rubella could come back. If they fall by 40%, polio might return too.

Dr. Mujeeb Basit, associate director of the Clinical Informatics Center at UT Southwestern Medical Center, said, “The numbers may not be exact, but the trend is clear. As vaccination goes down, infections rise fast. A 5% drop could mean thousands of cases. A 15% drop could mean millions.”