History and current situation (as of 03/20/2026)

1. What is the history of measles in the U.S.?

Measles is a vaccine-preventable disease.

Pre-vaccine era

Measles was first identified as an infectious agent from blood samples collected in 1757 and became a nationally notifiable disease in the US in 1912.¹ An average of 6,000 measles-related deaths were reported each year within the first decade of mandatory reporting.¹ Over the decade before the development of the measles vaccine in 1963, nearly all children contracted measles before the age of 15 years. During this period, measles caused up to 500 deaths, 48,000 hospitalizations, and 1,000 cases of encephalitis per year.¹

Vaccine development

The original measles vaccine was created in 1963, and the current vaccine was developed in 1968. The measles vaccine is a live vaccine, and it is usually combined with mumps and rubella (MMR) or mumps, rubella, and varicella (MMRV).¹

Measles vaccination in the U.S.

In 1978, the Centers for Disease Control and Prevention (CDC) set a goal to eliminate measles from the US by 1982.^1,2 Although this goal was not achieved, the widespread use of the measles vaccine in 1981 reduced reported measles cases by at least 80% compared to 1980.¹

In 1989, measles outbreaks among vaccinated school-age children prompted the recommendation of a second dose of the MMR vaccine for all children. Measles cases subsequently declined following the widespread implementation of the second-dose recommendation and improvements in first-dose MMR vaccine coverage.¹

Measles elimination in the U.S. and current events

In 2000, the U.S. declared measles eliminated, primarily attributed to high vaccination coverage and interrupted disease transmission for over 12 months.¹

However, vaccination rates have steadily declined since the COVID-19 pandemic, contributing to the resurgence of measles in the US. Significant outbreaks have occurred thus far in California (2015), New York (2019), and Texas (2025).^3-6

Other recent outbreaks include the 2019 outbreak in 31 states, which involved the highest number of measles cases in the U.S. since 1992, the 2019 outbreak in Ohio, and the 2024 outbreak in a Chicago migrant shelter.^7-9

2. How have vaccination rates in the U.S. changed recently?

After an initial decrease in vaccination rates during the COVID-19 pandemic, community vaccination rates increased in 2022, but were still below the 2019 pre-pandemic vaccination rates.³ During the 2023-2024 school year, vaccination coverage among kindergartners in the US decreased for all reported vaccines from the year prior, and was 92.7% for the MMR vaccine for kindergarten-aged children.^10,11 Coverage with MMR, DTaP, poliovirus vaccine (polio), and varicella vaccine (VAR) decreased in more than 30 states, compared to coverage the year before.¹¹

• Measles, Mumps, and Rubella

• Vaccination Coverage and Exemptions among Kindergartners

• National Immunization Survey-Child, United States, 2021–2023

3. What about the current measles outbreak?

As of March 19, 2026, 1487 cases (To date) have been reported from 32 different states. Among these cases, 94% are outbreak-associated (323 from 2026 and 1075 from outbreaks that started in 2025). Importantly, 92% of measles cases have been reported in individuals who are unvaccinated or have an unknown vaccination status.

Measles cases in 2025

As of March 19, 2026, 1487 cases (To date) have been reported from 32 different states. Among these cases, 94% are outbreak-associated (323 from 2026 and 1075 from outbreaks that started in 2025). Importantly, 92% of measles cases have been reported in individuals who are unvaccinated or have an unknown vaccination status.¹⁰

• CDC measles case count tracker

• Morbidity and Mortality Weekly Report (MMWR) for Measles