Measles Cases Surge to Highest Level in Decades

The U.S. is facing a severe public health crisis as measles cases have reached a peak not seen in over 30 years, largely due to declining vaccination rates and the spread of misinformation. Health officials are now scrambling to contain the outbreaks.

Record Number of Cases

As of early July 2025, the nation has recorded 1,281 confirmed measles cases, exceeding the total for all of 2019, according to the Johns Hopkins Measles tracker. Experts consider this a significant undercount, and the surge represents a 29-fold increase from the same period last year.

Measles had been declared eliminated in the U.S. in 2000. Before this year, the country saw approximately 180 cases annually.

Declining Vaccinations Fuel Outbreaks

The resurgence is mainly attributed to falling childhood vaccination rates, particularly in under-vaccinated communities such as West Texas, where a major outbreak began. About 95% of confirmed cases in 2025 were in individuals unvaccinated or with unknown vaccination status.

This year, measles has led to three deaths: two children in Texas and one adult in New Mexico, all unvaccinated. This matches the total number of U.S. measles deaths over the past 25 years. Experts fear the U.S. could lose its measles elimination status if current trends continue, risking a return to endemic spread.

Geographic Spread

While West Texas is a major epicenter, measles has spread alarmingly across the U.S. As of July 5, 2025, at least 38 states have reported cases, with 27 identified outbreaks (three or more related cases). States affected include:

Alaska, Arkansas, Arizona, California, Colorado, Florida, Georgia, Hawaii, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maryland, Michigan, Minnesota, Missouri, Montana, Nebraska, New Jersey, New Mexico, New York City, New York State, North Dakota, Ohio, Oklahoma, Oregon, Pennsylvania, Rhode Island, South Dakota, Tennessee, Texas, Utah, Vermont, Virginia and Washington.

Many cases result from local transmission, such as a recent Colorado spike linked to an infectious traveler on a plane, which then spread in the community. The broad age range of those affected suggests the outbreak developed over years due to persistent gaps in vaccine coverage. A key factor is anti-vaccination campaigns and disinformation.

Vaccination Rate Decline

A study in JAMA (Journal of the American Medical Association) found that MMR (measles, mumps, and rubella) vaccination rates have declined since the COVID-19 pandemic began. Among 2,066 counties in 33 states, 78% reported a decline. The county-level mean vaccination rate fell from nearly 94% pre-pandemic to about 91% after.

This is below the 95% threshold needed for herd immunity, a target the U.S. has missed for four years. Significant drops occurred in Hawaii (from 95% to 80%) and Wisconsin (lowest average rate, in the 70s). According to a recent CDC report, as of 2023, only 93.1% of children aged 19-35 months had received the MMR vaccine (CDC).

The link between declining vaccination rates and increased measles is clear. Most U.S. measles cases this year (95%-96%) occurred in unvaccinated individuals or those with unknown vaccination status.

Measles is highly transmissible, with one infected person able to transmit it to up to 12 others in a susceptible population. Without high vaccination rates, the virus spreads rapidly, threatening the return of once-eliminated diseases. Experts warn that if current trends persist, measles may become endemic in the U.S. within two decades.

Global Impact

The measles surge is not limited to the U.S. Canada and Mexico are also experiencing significant outbreaks. The Pan American Health Organization (PAHO) and World Health Organization (WHO) warn that the “overall risk of measles in the Americas Region is considered high” due to low vaccination rates.

The Americas have confirmed 7,132 measles cases and 13 deaths as of mid-June 2025, a 29-fold increase from the same period in 2024. Canada, Mexico, and the U.S. account for most cases, primarily affecting children under 5 and adolescents aged 10 to 19 years. 56% of cases were unvaccinated, and 35% had unknown vaccination status. Globally, WHO reported 88,853 confirmed measles cases in 168 member states as of June 6, 2025.

Mexico has reported 2,597 confirmed measles cases, including nine deaths, as of late June 2025, marking its worst outbreak in decades. It began in March, traced to an unvaccinated Mennonite boy who visited relatives in Seminole, Texas. Cases spread through Chihuahua’s Mennonite community via schools, churches, and workplaces.

The Mennonite community in Chihuahua has historically low vaccination rates due to misinformation and distrust of authorities. Some view vaccination as a matter of “freedom of expression” and prefer “to cure themselves in their own way,” sometimes even intentionally exposing children at “measles parties.”

Canada has reported 3,170 measles cases (confirmed and probable) and one death as of epidemiological week 23, 2025, far exceeding the 177 cases reported in all of 2024. This is the highest annual number of cases since measles elimination in 1998. The reported death was an infant born prematurely with congenital measles from an unvaccinated mother. Most cases (93%) in 2025 were exposed within Canada.

While outbreaks in the U.S., Canada, and Mexico have been concentrated in Mennonite communities with low vaccination rates, PAHO experts have not formally linked them genetically due to limited genetic sequencing. Travel links have been identified, such as cases in Colorado linked to Chihuahua, Mexico, and Canadian outbreaks linked to Michigan, underscoring that viruses do not respect borders.

Political Interference

The resurgence of measles is inflamed by actions taken by Health and Human Services (HHS) Secretary Robert F. Kennedy Jr. and his appointees. These actions are widely perceived as fostering mistrust in vaccines and threatening childhood vaccination programs.

On June 9, 2025, Kennedy dismissed all 17 members of the CDC’s Advisory Committee on Immunization Practices (ACIP), an unprecedented move. He claimed ACIP was “plagued with persistent conflicts of interest” and was a “rubber stamp.” Former CDC director, Dr. Tom Frieden, called these claims “total misrepresentation” and “classic misinformation.”

Two days later, Kennedy appointed eight new ACIP members, many known for vaccine skepticism, misinformation promotion, or opposition to public health practices.

During a recent meeting, chair of the ACIP and one of the authors of the Great Barrington Declaration, Martin Kulldorff, announced new working groups to “evaluate the cumulative effect of the recommended vaccine schedule.” Dr. Sean O’Leary of the American Academy of Pediatrics (AAP) criticized this as an “anti-vaccine trope.”

The committee’s agenda shifted to revisiting “long-settled questions” such as the safety of thimerosal, debunked as having any link to autism. Most U.S. vaccines have been thimerosal-free since 2001.

The withdrawal of a U.S. funding pledge to Gavi, the Vaccine Alliance, further compounds this crisis. The U.S. was a major funder, and this withdrawal of $1.2 billion could lead to over 1 million preventable child deaths within five years by disrupting immunization programs for 75 million children.

Public health experts warn that these “destabilizing decisions, made without clear rationale, may roll back the achievements of US immunization policy, impact people’s access to lifesaving vaccines, and ultimately put US families at risk of dangerous and preventable illnesses.”

The resurgence of vaccine-preventable diseases like measles and whooping cough is directly linked to these actions and the declining trust and vaccine uptake they foster. If current vaccination rates persist, measles may become endemic again in the U.S. within two decades, and a 10% decline in MMR vaccination could lead to 11.1 million measles cases over 25 years.