IMPLEMENTATION OF THE WORLD HEALTH ORGANIZATION WESTERN PACIFIC REGIONAL PLAN OF ACTION FOR MEASLES ELIMINATION

Abstract. The Western Pacific Region (WPR) is comprised of 37 countries such as China, Japan, Mongolia, Republic of Korea, The Socialist Republic of Vietnam, Papua-New Guinea, Australia, including Pacific Island Countries and Territories (21 countries of PICTs, approx. 3 million people) etc., with a population of 1.85 billion people. Among them, China is the largest and most populous (1.3 billion people) country of the Region. Large measles outbreaks were documented to occur in the Region. In 2003, the Regional Committee announced officially about the WPR action plan on measles elimination 2005, which, however, failed. Since 2012, WPR countries joined the WHO 2012–2020 Global Measles and Rubella Strategic Plan performing a routine measles vaccination (national immunization schedule) or within Expanded Programme on Immunization (EPI). Basically, a two-dose immunization strategy is followed in the WPR countries. Since 2002, measles supplementary immunization activities (SIAs) in children were conducted in the following countries: Japan, Laos, Vietnam, Philippines, Mongolia, Cambodia, Papua New Guinea, and China. Starting from 2005, measles management was considerably improved, demonstrating by 2012 decreased measles incidence rate down to 5.9 cases per million population. In last years, a decreased measles immunization coverage in decreed population groups was noted in the WPR countries that resulted in 2013–2015 measles epidemic involving almost all regional countries. In particular, in China measles incidence rate was 19.6 cases per million population, whereas in the Vietnam Papua New Guinea and Philippines it progressively increased reaching 182.8, 345.9 and 548.0 cases per million population, respectively. Early children not vaccinated according to schedule, adolescents and young adults dominated among measles patients. It was found that measles outbreaks were due to missed vaccination and increased level of vulnerability to measles. Children under one, adolescents and young adults who did not receive a two-dose measles vaccination were in risk group. Analyzing WPR measles epidemiology demonstrated that refusal of parents to vaccinate children, poor knowledge of advantages related to vaccination, insufficient immunization coverage in immigrants, travelers, subjects changing place of residence, workers of healthcare and educational facilities require special attention. In 2017–2018 season, the following measles genotypes were found in the WPR: D8 — Australia, New Zealand, Republic of Korea, Singapore, Japan; Н1 — China; В3 — Philippines, Australia and Japan; D9 — Singapore, Australia, Macau (China), Malaysia and Japan, Н2 strains endemic in Vietnam. According to the WHO, measles endemic transmission has been successfully interrupted; Australia, Macau, Mongolia and Republic of Korea are being verified to eliminate measles; Hong Kong (China) and Singapore (based on available information) are ready to verify measles elimination. Thus, in the Western Pacific Region measles elimination is achievable after solving current issues such as increasing and maintaining high-level routine vaccination and conducting measles supplementary immunization campaigns in epidemically important contact clusters.