Investigation of a measles outbreak in Brondong subdistrict, Lamongan district, Indonesia, 2023.

The measles outbreak was attributed to a decline in immunization coverage, particularly for the second dose of the measles-rubella vaccine. This decrease was driven by multiple factors, including the impact of the COVID-19 pandemic, misconceptions related to religious beliefs, and the long interval between the first and second vaccine doses, which contributed to the patients who were lost to follow-up. Collectively, these factors increased the vulnerability of children to measles infection.