Measles in the Western Pacific, 2013–2017: Resurgence and Recovery

This page summarizes a report in CDC's MMWR by the World Health Organization (WHO) and CDC, covering 2013–2017.

In 2005, the WHO Regional Committee for the Western Pacific Region (WPR), 37 countries and areas with about 1.8 billion people, set a goal of eliminating measles by 2012. Elimination means no endemic measles virus transmission in an area for at least 12 months, with a well-performing surveillance system in place. The strategy has three parts:

1. at least 95% coverage with 2 doses of measles-containing vaccine (MCV), through routine immunization and, when needed, supplementary immunization activities (SIAs);
2. high-quality case-based surveillance, with timely, accurate lab testing to confirm or discard suspected cases and to genotype the virus;
3. outbreak preparedness for rapid response and proper case management.

Vaccination

• In 2016, 18 of 36 reporting countries (50%) reached at least 95% MCV1 coverage, and 11 (31%) reached it for both doses.
• As of 2017, only Solomon Islands and Vanuatu had not introduced MCV2.
• Of 18 national SIAs in 2013–2017, seven (39%) reported at least 95% administrative coverage. Japan also ran yearly SIAs for schoolchildren aged 13 and 17.

Surveillance

All countries and areas report case-based measles and rubella data to WHO each month, with 21 Pacific Island countries and areas reporting as one block. WHO's Global Measles and Rubella Laboratory Network confirms and genotypes cases. From 2013 to 2017:

• countries meeting the national target for suspected cases discarded as nonmeasles (at least 2 per 100,000) fell from 11 (65%) to nine (53%), while those meeting it subnationally rose from one (6%) to two (12%);
• suspected cases adequately investigated fell from 92% to 89%;
• suspected cases with adequate specimens fell from 90% to 89%;
• blood specimens with results within 7 days rose from 84% to 98%.

The resurgence

After a record low of 5.9 cases per million in 2012, measles came back:

• Endemic countries: seasonal transmission increased in China, and Malaysia and the Philippines had large nationwide outbreaks.
• Countries that had eliminated measles: importations set off outbreaks in Australia, Cambodia, Japan and South Korea, and a large one in Mongolia.
• Endemic, low-incidence countries: more importations led to outbreaks in New Zealand, Papua New Guinea, Singapore, Solomon Islands and Vietnam.

Regional incidence rose from 19.2 per million in 2013 to 68.9 in 2014, then fell to 5.2 in 2017, a new historic low. The main genotypes were H1 in China, B3 in the Philippines, and D8 and D9 in Malaysia and Vietnam.

The decline came from controlling the outbreaks in Vietnam (2013–2014) and Mongolia (2015–2016), the burnout of the Philippine outbreak (2013–2014), and China's accelerated measles control after its 2010–2011 outbreak.

Verification

WHO's Regional Verification Commission finalized verification guidelines in April 2013 and revised them in 2016 to include rubella. As of its September 2017 meeting, eight countries and areas (47%) had been verified as having eliminated measles: Australia, Brunei, Cambodia, Hong Kong (China), Japan, Macao (China), New Zealand and South Korea. After Mongolia's 2015–2016 outbreak lasted more than 12 months, the commission found that endemic transmission had been reestablished there.

Lessons

The resurgence exposed several problems:

• Changing epidemiology: more cases among adolescents, young adults and infants too young to be vaccinated, and uneven patterns across subnational areas and at-risk groups in large countries.
• Weak systems: routine immunization could not reach and hold high population immunity, and some national laboratories could not do serologic testing fast enough during outbreaks.
• Weak policies: delayed outbreak investigation, insufficient response and measles spreading in health facilities.
• Too little involvement of local governments, the private sector, societies and communities.

High reported coverage alone does not bring elimination. In October 2017 the 68th WHO Regional Committee for the Western Pacific endorsed a new Regional Strategy and Plan of Action for Measles and Rubella Elimination, with 31 strategies in eight areas: planning, immunization services, surveillance, laboratory support, program review and risk assessment, outbreak preparedness and response, partnerships and communication, and progress monitoring and verification. It is meant as a base for national plans, and subnational plans in large countries.

Sources

• Hagan JE, Kriss JL, Takashima Y, et al. "Progress Toward Measles Elimination — Western Pacific Region, 2013–2017." MMWR 67(17). https://www.cdc.gov/mmwr/volumes/67/wr/mm6717a3.htm
• Supplementary surveillance table: https://stacks.cdc.gov/view/cdc/53519
• The report's figure is not reproduced, because the report was prepared jointly with WHO.