Measles is spreading worldwide again after a decline and stagnation in vaccination coverage created conditions for new outbreaks. In 2023, approximately 15.6 million cases and around 118,000 deaths were recorded, according to an international study covering 204 countries and published in the journal Nature Medicine. The study was led by epidemiologist Ben Sartorius of the University of Washington.
The data show a sharp reversal of a long-standing positive trend. Between 1990 and 2019, the global incidence of measles fell by around 80 percent, while mortality declined by approximately 90 percent. Between 2019 and 2023, however, the number of cases increased by around 40 percent, while deaths rose by 12 percent. According to the researchers, the consequences of changes in vaccination coverage emerge with a delay.
The share of children who received their first dose of measles vaccine increased from 67.2 percent in 1990 to 83.6 percent in 2019, but then fell to 81 percent in 2023. There has been long-term progress with the second dose—from 14.4 percent in 1990 to 71.4 percent in 2023—but the level remains below that required to sustainably interrupt transmission of the virus.
The World Health Organization recommends that at least 95 percent of the population be immunized with two doses. “Two doses of a vaccine containing a measles component provide 97 percent protection against infection and the potentially severe consequences of the disease,” the WHO states.
The situation in the United States shows how a decline in immunization coverage can lead to the rapid spread of the disease. In Pennsylvania, 1,338 cases had been reported as of October 23—the highest number for a single state since 1991. Measles has led to 255 hospitalizations and six deaths, two of them children.
In New York, a child’s death linked to measles has also been reported—the first such case in the state in 30 years. Nationwide, 2,289 cases were recorded in 2025, while as of October 29, 2026, confirmed cases stood at 4,852. The Centers for Disease Control and Prevention уточняват, че данните за 2025 и 2026 г. са предварителни и подлежат на промяна.
Measles remains one of the most common infectious diseases that can be prevented through vaccination, particularly in low-income countries. According to the study’s authors, insufficient immunization coverage and vaccine hesitancy create a risk that the disease will return even to countries that achieved its elimination years ago.