Measles resurgence hits young children hardest

Estimated measles cases among children under five rose from 11.1 million in 2019 to 15.6 million in 2023, according to a Global Burden of Disease analysis published in Nature Medicine on October 21. The rise represents a 40 percent increase over four years and reverses much of the progress recorded in the decades before the pandemic. Researchers examined cases, deaths and vaccination coverage across 204 countries and territories from 1990 through 2023, using surveillance records, surveys and vital records to build the estimates.

The paper is titled Global and regional burden of measles and vaccine coverage among children under 5 years, 1990-2023. Its central finding is the measles resurgence among the youngest children, a group at higher risk of severe illness when infected. Deaths in that age group were estimated at about one hundred eighteen thousand in 2023, up 12 percent from 2019, according to reports on the study.

What the global study found

Between 1990 and 2019, estimated cases worldwide fell by nearly 80 percent. That long decline stalled after routine immunisation programmes were disrupted during the COVID-19 pandemic, according to the University of Queensland, where lead researcher Benn Sartorius is based at the Frazer Institute. Sartorius said childhood immunisation rates had moved backward since the pandemic and that the change had contributed to a worldwide return of measles in young children.

The study linked the return to disrupted immunisation programmes, strained health systems and reduced funding, rather than to a change in the virus itself. In a statement reported by the university, Sartorius called for urgent action to restore routine programmes and to build health systems able to sustain high coverage during a crisis. The data, Sartorius said, could help health authorities find under-vaccinated populations and direct catch-up vaccination to the places where support is needed most.

Vaccination gaps remained wide in 2023. An estimated 23.7 million infants, about a fifth of infants worldwide, missed a first dose of measles-containing vaccine that year. Sub-Saharan Africa accounted for half of those missed doses, while South Asia accounted for 20 percent of them. Sub-Saharan Africa also recorded the highest mortality rate in the study period, according to the university summary of the findings.

Measles spreads through the air when an infected person coughs or sneezes, and the World Health Organization estimates that a single case can generate up to 18 secondary infections where immunity is low. A study published in The Lancet Global Health in 2023 estimated that measles was fatal in as many as three in every hundred infected infants under a year of age in low- and middle-income countries in 2019. Two doses of measles vaccine were estimated to have prevented nearly 59 million deaths between 2000 and 2024, according to the University of Queensland summary, which makes the recent fall in coverage a direct threat to those gains.

Australasia stood out as an exception in the regional picture. The region recorded among the largest gains in second-dose coverage from 1990 to 2019 and, by 2023, had the highest coverage of any region, according to the study summary. That contrast shows that high coverage can be maintained, but it also underlines how uneven progress has become since the pandemic disrupted services in many other regions.

Why the United States figures matter

The global pattern has a direct counterpart in the United States. As of October 22, the Centers for Disease Control and Prevention reported 4,588 confirmed measles cases in the country in 2026, with 43 outbreaks recorded during the year. About 96 percent of the confirmed cases were linked to outbreaks, according to the CDC page, which was updated on October 23. The CDC reported three deaths in the United States in 2026 on the same page.

For comparison, the CDC reported a full-year total for 2025 that was well below the 2026 figure already reached by late October. The 2025 total was 2,289 confirmed cases, with 48 outbreaks reported during that year. The gap between the years shows that the current year is not a small fluctuation in reported cases, but a substantially larger outbreak burden, driven largely by cases linked to recognised outbreaks.

Kindergarten coverage for measles, mumps and rubella vaccine has also slipped in the United States. CDC data show coverage among kindergartners fell from 95.2 percent in the 2019-2020 school year to 92.4 percent in the 2025-2026 school year, leaving about two hundred eighty thousand kindergartners at risk during the current school year, according to the agency. When coverage falls below 95 percent in a community, the CDC says most people are no longer protected through community immunity, and pockets of unvaccinated people can allow an imported case to spread quickly.

Measles was declared eliminated in the United States in 2000, meaning spread inside the country had stopped and new cases came only from travellers infected abroad. The CDC says that pattern still holds in principle, but travellers infected abroad can still bring the virus back and spread it to people who are not protected. State health departments lead outbreak investigations, the CDC says, and states notify the agency of confirmed cases.

What protection looks like

The CDC says a single dose of MMR vaccine is 93 percent effective at preventing measles, while the full course is 97 percent effective. Breakthrough infections can occur, the agency says, especially in communities where a large amount of virus is circulating, but the number of breakthrough infections is consistent with earlier years. The practical implication, according to the CDC guidance, is that high coverage in a community matters more than any single case count: where coverage is high, an imported case has fewer susceptible contacts and an outbreak is less likely to grow.

For parents and health services, the study points to a specific task. Catch-up vaccination for children who missed a dose during pandemic disruption, plus routine checks at school entry, can close the gaps that the global analysis identified. Health authorities in lower-resourced settings face the largest burden, the study found, because missed doses are concentrated there and health systems have fewer reserves to run catch-up campaigns. In higher-income countries, the task is different but related: finding small pockets of low coverage before an imported case reaches them.

Other recent health reporting on this site has examined different ways of spotting risk earlier, including a catheter that reads artery plaque chemistry and structure in a single pass and research into a hidden HIV reservoir. Those stories concern different conditions, but they share a theme with the measles findings: earlier detection and complete follow-through matter when a health risk can spread or worsen quietly.

Sources for this article include the University of Queensland summary of the Nature Medicine study and the CDC measles cases and outbreaks page, which gives the latest United States counts and kindergarten coverage figures. Both sources were checked on October 24, 2026.