Table 1.

Examples of locations with changes in age distribution of Japanese encephalitis cases following implementation of Japanese encephalitis vaccination programs

Country	Vaccination program information	Early period	Disease burden and age distribution in early period	Later period	Disease burden and age distribution in later period	References
Japan	Widespread childhood vaccination from 1967	1956–1964	Median of 1,979 cases annually (range: 1,205–4,538); ∼30–60% cases each year in children aged < 15 years	1982–2004	Median of seven cases annually (range: 2–54); 78% cases aged ≥ 40 years; highest number of cases in 60–69 year age group	29 – 31
South Korea	Vaccination began in late 1960s, but program substantially expanded after 1983	1955–1966	Mean annual IR 7.3/100,000; 92% (20,286 of 22,111 cases) aged ≤ 14 years	2010–2014	Mean annual IR of 0.03/100,000; 89% aged ≥ 40 years	29 , 32
Taiwan	Mass vaccination of children began in 1968, followed by routine childhood immunization	1966–1970	Aged < 30 years: mean annual IR 2.8 per 100,000; aged ≥ 30 years: mean annual IR 0.04 per 100,000; > 90% cases in persons aged 0–29 years (mostly 0–14 years)	2002–2012	Aged < 30 year: mean annual IR 0.05 per 100,000 Aged ≥ 30 years: mean annual IR 0.2 per 100,000; 83% cases aged ≥ 30 years (including 35% ≥ 50 years)	28 , 29
Sri Lanka	Childhood immunization program began in 1988 with phased implementation of campaigns for children aged 1–10 years in higher risk districts. In 2011, national routine immunization program for children aged 9 months established	1985–1987	Mean annual IR 3.3 cases per 100,000; high risk age group: children < 15 years	2011–2015	Mean annual IR 0.2 cases per 100,000; 73% of cases among persons aged ≥ 20 years	33 , 41
Malaysia (Sarawak state)	Routine childhood vaccination began in 2001	1996–2001	Mean annual IR 1.4 per 100,000; mean age 7.5 years (SD: 5.8 years)	2010–2015	Mean annual IR 0.5/100,000; mean age 16.9 years (SD: 10.1 years)	40

IR = incidence rate.