The World Health Organization is pressing governments to reinforce routine childhood vaccination after reporting a sharp increase in measles cases worldwide during the first half of 2026. Health officials say the rise points to gaps in immunization coverage that can allow highly contagious diseases to spread quickly.

Measles is one of the most transmissible viral infections, and experts warn that even modest drops in vaccine uptake can trigger outbreaks. The WHO said countries need to restore and protect regular immunization services, especially for children who may have missed shots because of strained health systems, conflict, poverty, or disruption in care.

Public health specialists have long said measles is a test of a country’s broader vaccine infrastructure. When routine programs weaken, the effects can extend beyond a single disease and leave communities exposed to other preventable infections as well.

The latest warning comes as health agencies continue to monitor uneven vaccine access across regions. WHO’s message is clear: maintaining routine immunization is essential to preventing avoidable illness, protecting children, and stopping outbreaks before they spread further.