Newsletter Vol 1. No 15

There have now been more measles cases in 2025 than in any other year since the contagious virus was declared eliminated in the United States in 2000, according to new data released last week by the Centers for Disease Control and Prevention.

The grim milestone represents an alarming setback for the country’s public health and heightens concerns that if childhood vaccination rates do not improve, deadly outbreaks of measles — once considered a disease of the past — will become the new normal.

Experts fear that with no clear end to the spread in sight, the country is barreling toward another turning point: losing elimination status, a designation given to countries that have not had continuous spread of measles for more than a year.

Most of the cases this year have been tied to the Southwest outbreak, the largest single outbreak since 2000, which began in January in a Mennonite community in West Texas and has since jumped to New Mexico and Oklahoma. Cases have also popped up in 38 states, which experts say represents a concerning vulnerability to diseases of the past. Because of the contagiousness of the virus, researchers often think of measles as the proverbial canary in a coal mine. It is often the first sign that other vaccine-preventable diseases, like pertussis and Hib meningitis, might soon become more common.

In total, 1,288 people have had a confirmed case of measles this year, 92 percent of whom were unvaccinated or whose vaccination status was unknown.

While measles symptoms typically resolve in a few weeks, the virus can cause pneumonia, making it difficult for patients, especially children, to get oxygen into their lungs. It may also lead to brain swelling, which can cause lasting damage, including blindness, deafness and intellectual disabilities.

The outbreak’s full effect on public health may not be apparent for years.

The virus causes “immune amnesia” making the body unable to defend itself against other illnesses it has already been exposed to and leaving patients more susceptible to future infections. And very rarely, the virus can cause a degenerative and almost always deadly neurological condition that may appear a decade after the original infection.

Until now, 2019 held the record for the highest number of measles cases since the virus was eliminated. (Before that, large outbreaks sickened tens of thousands of people in some years.) Most of the 1,274 cases that year were connected to a large outbreak that spread through Orthodox Jewish communities in New York State for nearly 12 months.

While the country has faced large measles outbreaks in the past, a confluence of factors have made it particularly difficult to rein in the virus this year.

Nationally, the measles vaccination rate fell during the Covid-19 pandemic and has not rebounded to the 95 percent required to stem the spread of the virus in a community. Roughly 93 percent of children in kindergarten in the 2023-24 school year had received the measles, mumps and rubella shot, though rates in some parts of the country were far lower.

Another challenge in controlling this year’s outbreak is the global rise of measles. Large outbreaks have spread through Mexico and parts of Canada, which has had a record number of cases this year. This spring, the World Health Organization announced that Europe had reported the highest number of measles cases in more than 25 years.

The global rise means the virus is constantly reintroduced into the country through visitors, giving it repeated opportunities to find pockets of unvaccinated Americans, he said.