You probably know measles as something older generations remember all too well. Most people were told it had been pushed close to the edge of elimination. The last few years have changed that story.
A new global study in Nature Medicine found that measles cases in children under five rose about 40 percent between 2019 and 2023. The analysis was led by Associate Professor Benn Sartorius at the University of Queensland.
In raw numbers, estimated cases climbed from 11.1 million in 2019 to roughly 15.6 million in 2023. About 23.7 million infants, or one in five worldwide, missed their first measles dose that year.
The researchers pulled data from 204 countries and territories. Half of the missed doses were in Sub-Saharan Africa, with another fifth in South Asia. Before the pandemic, global measles cases had fallen almost 80 percent between 1990 and 2019.
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Why vaccination coverage has to stay very high
Measles is one of the most contagious viruses known. The World Health Organization estimates a single infected person can seed up to 18 secondary infections when community immunity is low.
To stop the virus from spreading, public health agencies have long said coverage must sit at or above 95 percent. That is the level where enough people are protected to keep the virus from circulating in a community.
That is why small drops matter. According to the CDC, kindergarten MMR coverage in the United States fell to 92.4 percent in the 2025-2026 school year, down from 95.2 percent in 2019-2020. More than three-quarters of states are now below the 95 percent target.
What the gap looks like in the United States
The United States is in its worst measles year in more than three decades. The CDC has confirmed 4,410 cases as of October 15, 2026, more than at any point since 1991. The outbreak now spans 47 jurisdictions, and 96 percent of cases are tied to local outbreaks.
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About 95 percent of US cases are in people who are unvaccinated or whose vaccine status is unknown, CDC data show. Pennsylvania health officials have confirmed five measles deaths in that state alone this year.
Sartorius said the resurgence "backtracks on decades of progress, where a nearly 80 per cent decline in measles cases was recorded worldwide between 1990 and 2019."
He has urged governments to restore routine immunization and build health systems that can hold vaccine coverage up during the next global crisis.
For American families, the CDC recommends two doses of the MMR vaccine. The first is given between 12 and 15 months of age, the second between 4 and 6 years. Older children or adults who are not sure of their status can ask a doctor about a catch-up dose.
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This article is made and published by Aksel Kryhlmand, who may have used AI in the preparation.