Global Surge in Measles Cases Raises Questions About Vaccination Timing

Measles outbreaks are increasing worldwide, with recent data showing an alarming rise in cases. In 2023 alone, approximately 10.3 million people contracted measles, representing a 20% increase compared to the previous year. These outbreaks are occurring across various regions, including the United States, Europe, and the Western Pacific, which encompasses Australia. For instance, Vietnam reported thousands of cases in 2024 and 2025, highlighting the persistent threat of the disease.

The frequency and scale of these outbreaks are largely attributed to declining vaccination rates, especially after the COVID-19 pandemic, which disrupted immunization programs globally. Measles, caused by a highly contagious virus in the Morbillivirus genus, spreads easily through respiratory droplets that can linger in the air for hours. Despite often causing mild symptoms like fever, cough, and rash, measles can lead to severe complications, including brain inflammation and immune suppression, which may result in long-term health issues or death.

According to the World Health Organization, maintaining vaccination coverage above 95% with two doses of the measles vaccine is essential for herd immunity. Currently, global vaccine coverage has not met this threshold, facilitating the persistence of outbreaks. In Australia, for example, 77 cases were recorded in the first five months of 2025, an increase from 57 cases all of 2024. Most of these cases are linked to international travel, emphasizing the importance of vaccination for travelers.

Children are most vulnerable to measles, but maternal antibodies provide initial protection at birth. Generally, children in regions with high measles circulation receive their first vaccine dose around nine months of age because maternal antibodies diminish by then, making infants susceptible. The standard practice is to administer two doses: the first at 12 months, and the second 6-9 months later, to ensure immunity in about 85-90% of vaccinated children.

Research suggests that maternal antibodies decline earlier than previously believed, with only 30% of infants at four months still possessing these protective antibodies. A recent review of over 8,000 babies in low- and middle-income countries indicates that earlier vaccination might be beneficial, especially when measles is rampant. In Australia, the current schedule is unlikely to change soon, but in other countries, some policymakers are considering earlier vaccination for high-risk groups.

Ensuring high vaccination rates remains vital for controlling measles. Adults born before 1966 are generally considered immune due to natural infection. Individuals uncertain of their vaccination status should consult health records or their healthcare providers for catch-up immunizations. Expanding vaccination coverage is a critical step toward preventing future outbreaks and protecting vulnerable populations.

source: https://medicalxpress.com/news/2025-06-measles-cases-surging-globally-children.html