The United States has crossed a grim threshold in its ongoing battle against measles, recording more than 2,000 cases in a single year for the first time in over three decades. This alarming resurgence of a disease officially declared eliminated in the country 25 years ago is being fuelled by declining childhood immunisation rates, public health officials warn.
A Nationwide Surge in Preventable Disease
As of 30 December 2025, 2,065 Americans have been infected with measles and three people have died. This marks the largest outbreak since 1992, when 2,126 cases were reported. The Centres for Disease Control and Prevention (CDC) noted a rapid increase, with 107 new cases recorded in less than two weeks towards the end of the year, including the first case in Connecticut since 2021.
The outbreak is widespread, with significant clusters in several states. South Carolina saw cases jump from 142 to 181, while Utah's outbreak grew from 122 to 156. Arizona recorded 14 new cases, bringing its total to 196. California and Nevada also reported new infections. This represents a dramatic spike from 2024, when states like South Carolina and Utah had only one and zero cases respectively.
The Root Cause: Falling Vaccination Rates
The primary driver of this crisis is a drop in the uptake of the Measles, Mumps, and Rubella (MMR) vaccine. While the national MMR vaccination rate stands at 92.5%, this is below the 95% community immunity threshold required to prevent the virus from spreading. In some states, the rates are critically low: only 89% of kindergarteners in Utah were vaccinated for the 2023-2024 school year, with Arizona at a similar level and South Carolina at 92%.
Dr Renee Dua, a medical advisor, stated plainly: 'The current measles outbreaks in the US are a direct consequence of falling childhood vaccination rates... We are seeing real consequences: preventable outbreaks, hospitalisations, and deaths.' The data supports this: 93% of current cases are in individuals who were either unvaccinated or whose vaccination status is unknown.
Severe Impact and Public Health Emergency
The outbreak has placed a severe burden on the population, particularly children. Of the total cases, 537 are in Americans under five years old, and 865 are in those aged 5 to 19. Hospitalisations have affected 11% of patients, with young children under five making up 20% of those admitted.
Measles is one of the world's most contagious diseases; an unvaccinated person has a 90% chance of infection if exposed. It can lead to severe complications including pneumonia, seizures, and encephalitis (brain swelling), which can cause permanent damage or death. Before the two-dose vaccine was introduced, measles caused up to 500 deaths, 48,000 hospitalisations, and 1,000 cases of encephalitis annually in the US.
Public health experts now fear that the United States is at risk of losing its hard-won measles elimination status if transmission continues unabated. The situation underscores the critical importance of vaccines, which remain among medicine's safest and most effective tools, and the urgent need to rebuild public trust in immunisation programmes.
