Measles in young children surged worldwide in 2023, with an estimated 15.6 million children under five catching the disease, according to a major global study published in Nature Medicine. The findings, released on October 21, 2026, show cases in that age group rose 40 percent between 2019 and 2023, while deaths rose 12 percent, reversing decades of progress against one of the world's most contagious diseases.

The study, led by researchers at the University of Queensland with the GBD 2023 Measles Collaborators, covers 204 countries and territories from 1990 to 2023. It estimates that 118,000 children under five died from measles in 2023. The researchers warn that the rebound is not a mystery: routine immunisation was disrupted, health systems were stretched, and millions of infants missed their first measles dose.

Key Points

• An estimated 15.6 million children under five caught measles in 2023, up 40 percent since 2019.
• About 118,000 children under five died from measles in 2023, up 12 percent since 2019.
• At least 23.7 million infants, one in five worldwide, missed their first measles dose in 2023.
• Sub-Saharan Africa and South Asia carried the highest burden, with Africa accounting for half of missed shots.
• Worldwide two-dose coverage stood at 77 percent in 2025, well below the 95 percent needed to stop transmission.

What Happened

The new study gives the fullest picture yet of how measles returned after the COVID-19 pandemic. Between 1990 and 2019, measles incidence had fallen by about 80 percent and mortality by about 90 percent, as vaccination programmes expanded around the world. That long decline has now gone into reverse for young children, the group most at risk of severe disease.

In 2023, the study estimates, 15.6 million children under five were infected. The death toll in that age group reached 118,000. Those figures are modelled estimates, built from surveillance data, vaccination records and disease modelling across 204 countries and territories. They are higher than a separate assessment by the World Health Organization and the US Centers for Disease Control and Prevention, which put total measles cases across all ages in 2023 at 10.3 million, with 107,500 deaths. The two tallies use different methods and cover different age groups, and they should not be added together.

What both assessments agree on is the direction of travel. After years of decline, measles is back, and it is hitting the youngest children hardest. Measles spreads through the air when an infected person coughs or sneezes, and it can linger in the air after that person has left a room. In places where immunity is low, researchers note, a single case can generate up to 18 secondary infections.

Background and Context

The pandemic broke that protection in many places. Clinics closed or were overwhelmed, vaccination campaigns were postponed, and parents in some areas lost contact with routine health services. Funding and health-system capacity also suffered. The result, the study finds, was a sharp rise in missed doses. In 2023, at least 23.7 million infants, about one in five worldwide, missed their first measles dose. Africa accounted for 50 percent of missed shots and South Asia for 20 percent, reflecting both large birth cohorts and weaker routine immunisation systems.

Measles in Young Children

Measles in young children is especially dangerous because the disease does more than cause a rash and fever. In young children, it can lead to pneumonia, brain swelling, severe diarrhoea and blindness, and it can weaken the immune system for months afterwards, leaving children vulnerable to other infections. Children under five, and especially infants, face the highest risk of death and serious complications.

That is why the 40 percent rise in cases among under-fives between 2019 and 2023 matters more than a headline number alone. It means the youngest, least protected children are bearing the brunt of the rebound. It also means that catching up on missed doses is urgent: every unvaccinated infant is both at personal risk and a link in a chain of transmission that can reach newborns and immunocompromised people who cannot be vaccinated themselves.

Reactions and Quotes

The study's authors present the findings as a warning, not just a tally. They argue that post-pandemic disruption to routine immunisation, funding and health systems explains much of the rebound, and they warn that without a sustained catch-up effort, measles will keep finding unvaccinated children. Their message, in essence, is that the tools to prevent these infections already exist, and the failure is one of reach, not science.

Why It Matters

This study matters because it quantifies a reversal that health workers have been warning about since the pandemic. A 40 percent rise in cases and a 12 percent rise in deaths among children under five, in just four years, erases part of a generation of progress. It also matters because measles is preventable. Unlike many diseases that dominate global health headlines, measles has a safe, effective and inexpensive vaccine, and the deaths counted in this study were, in principle, avoidable.

What Happens Next

The immediate next step is catch-up vaccination. Health agencies are expected to use studies like this one to target supplementary immunisation campaigns at the places and age groups with the largest gaps, especially children who missed doses in 2020 to 2023 and are now older but still unvaccinated. In many countries, that means combining measles vaccination with other routine childhood vaccines in outreach clinics, schools and community campaigns.

For parents, the advice from health authorities remains unchanged and simple: check that children have received both recommended measles doses on schedule, and ask a doctor or clinic if there is any doubt. In a year when measles infected an estimated 15.6 million young children, that check is the single most effective protection available.

Frequently Asked Questions

How many young children caught measles in 2023? The study estimates 15.6 million children under five, up 40 percent from 2019, with 118,000 deaths in that age group.

Why did measles cases rise? Researchers blame post-COVID disruption to routine immunisation, funding and health systems, which left millions of infants without their first dose.

How many infants missed their first dose? At least 23.7 million infants, about one in five worldwide, missed their first measles dose in 2023.

What coverage is needed to stop measles? About 95 percent two-dose coverage is needed to stop transmission. Worldwide two-dose coverage was 77 percent in 2025, according to WHO figures cited in the study's coverage.

How does this study differ from WHO-CDC figures? The WHO-CDC assessment put 10.3 million cases and 107,500 deaths across all ages in 2023, using different methods. The new study models under-fives only and gives higher estimates; the two should not be combined.

Related coverage: New York measles death: child dies in Lewis County, first in 30 years and Energy drinks linked to heart attacks in young adults, new FDA study finds.