Measles Cases Surge in the U.S.

Measles is making a troubling comeback in the United States, showing no signs of slowing down over the past two years.

As of July 22, the Johns Hopkins University Tracker noted a total of 2,295 confirmed cases of measles in the country, surpassing the previous year’s total of 2,286 cases.

Health experts are sounding alarms as a traveler with measles may have infected guests at a hotel in the Los Angeles area.

While cases have been popping up throughout the nation, outbreaks are reportedly escalating in Pennsylvania, South Carolina, Florida, Virginia, Utah, Texas, and Arizona. Notably, Texas had the largest outbreak in 2025, with 803 infections recorded across the state.

The CDC’s most recent update, issued on July 17, detailed 34 new outbreaks in 2026, down from 48 in 2025. Most of the recent cases are associated with local outbreaks, but some have connections to visitors from abroad.

Data shows a concerning trend: in both this year and last, around 93% of all measles cases involved individuals who had either not been vaccinated against measles, mumps, and rubella (MMR) or whose vaccination statuses were unknown.

Many cases primarily affect children and teenagers aged 5 to 19. The CDC has reported no deaths in 2026, although three were recorded in the previous year.

After years of declining incidence, the rise in measles cases is notable, especially since health officials had announced the disease’s eradication back in 2000.

The transmission of measles can occur through direct contact with infected droplets or via the air when an infected person coughs, sneezes, or even breathes. The virus can remain viable in the air for up to two hours post-exposure.

Measles symptoms typically emerge within a week or two, commonly starting with high fever, cough, runny nose, and red, watery eyes. After a few days, flat red spots may appear, beginning on the face and spreading downward. The virus is most contagious during the four days before and four days after the rash manifests.

Community Immunity

Dr. Mark Siegel, a senior medical analyst, highlighted the extreme contagiousness of measles. “Measles is so contagious that up to 90% of people who are susceptible and come into contact with an infected person will contract it,” he explained, emphasizing community protection through vaccinations. “We require a 95% vaccination rate to achieve herd immunity.”

This herd immunity threshold is calculated based on the disease’s contagious nature and how well vaccination or past infections prevent its spread. “In this context, two doses of the vaccine are nearly 100% effective, and immunity from a measles infection typically lasts a lifetime,” Siegel noted. He stressed that promoting vaccinations is about protecting the broader community, particularly those who can’t receive them due to health reasons.

Furthermore, Siegel expressed concern that the U.S. might risk losing its measles-free status given the increase in active outbreaks, which seem to suggest ongoing community transmission rather than isolated incidents tied to international travel.

The CDC advises that everyone should receive two doses of the MMR vaccine, as it remains the most effective line of defense against measles. Individuals showing symptoms or who suspect they’ve been exposed are urged to self-isolate and contact a healthcare provider before visiting a clinic.