A highly contagious viral disease that was declared eliminated in the U.S. in 2000 but continues to cause outbreaks due to declining vaccination rates.
Measles (rubeola) is a highly contagious viral infection caused by the measles virus, a paramyxovirus. It is one of the most infectious known diseases, with an R0 (basic reproduction number) of 12-18, meaning that one infected person can transmit the virus to 12-18 others in a completely susceptible population (CDC, 2024).
Before the introduction of the measles vaccine in 1963, an estimated 3-4 million people contracted measles annually in the United States, resulting in 400-500 deaths. The vaccine led to a 99% reduction in measles cases in the U.S. The disease was declared eliminated in 2000, meaning there was no continuous transmission for more than 12 months (CDC, 2024).
However, measles remains endemic in other parts of the world, and importations continue to occur. Recent years have seen resurgence in communities with low vaccination rates, including notable outbreaks in 2019 and 2024-2025.
Globally, measles remains a leading cause of vaccine-preventable death. The WHO estimates that in 2022, there were 136,000 measles deaths worldwide, mostly among children under 5 years old (WHO, 2024).
In 2019, the U.S. experienced 1,282 individual measles cases across 31 states - the largest number since 1992. This was largely driven by outbreaks in under-vaccinated communities. In 2024, new outbreaks have been reported in multiple states (CDC, 2024).
Most measles cases in the U.S. occur among unvaccinated individuals who traveled to areas with ongoing transmission and brought the virus back to their communities. The virus spreads quickly in settings with low vaccination rates, such as schools and daycare centers.
Vaccination remains the most effective strategy for preventing measles. The following describes established medical consensus for clinical management for those who contract infection.
Treatment is primarily supportive — maintenance of hydration and management of fever. Vitamin A supplementation is recommended by CDC and AAP to reduce complications and mortality. Dosages by age: 50,000 IU for infants under 6 months, 100,000 IU for infants 6–11 months, 200,000 IU for children 12 months and older — given on two consecutive days. Note: Evidence is strongest in settings with high prevalence of Vitamin A deficiency. Vitamin A does not prevent measles and must be administered under medical supervision. Secondary bacterial infections (pneumonia, otitis media) should be treated with antibiotics.
Disclaimer: This information is for educational purposes only. Treatment decisions must be made by a qualified healthcare provider.