Continued increase in measles cases in the Western Pacific Region

As cases increase, the risk of outbreaks due to international spread also increases. In the Western Pacific Region, measles cases increased by 743% between 2022 and 2024. As of 20 March 2025, measles outbreaks have been reported in Cambodia, the Lao People’s Democratic Republic and Mongolia, with continued measles virus transmissions in Malaysia, the Philippines and Viet Nam (Figure 1). Additionally, imported measles cases linked to international travel in the Region have been reported by Australia, Canada, Hong Kong SAR (China), Japan, Mexico, Mongolia, New Zealand, the Republic of Korea, Singapore and the United States of America.

Figure 1: Measles incidence rate, by country, in WPR, March 2025

Sources:
• National measles and rubella monthly reports to the WHO Western Pacific region, as of 20 March 2025;
• United Nations, Department of Economic and Social Affairs, Population Division World Population Prospects 2022 revision

In the past five years, backsliding in routine immunization coverage, disruptions to immunization during Covid-19 pandemic, and delays in required catchup vaccination activities have set measles prevention back. Measles prevention requires 95% children to receive 2 doses of measles vaccine. The vaccination coverage for the two doses of measles-containing vaccine (MCV2) decreased from 93% in 2019 to 90% in 2023. Nearly 1.7 million children missed receiving any dose of MCV in 2023. (Figure 2)

Figure 2: Measles vaccination coverage, 2019-2023 (WUENIC, 2023)