Trends and Age-Period-Cohort Effect on Acute Hepatitis B Incidence - China, 2005-2021

This study analyzed long-term trends in the incidence of acute hepatitis B (AHB) in China, focusing on age, period, and cohort effects on incidence.

Data on AHB from 2005 to 2021 were extracted from the National Notifiable Disease Reporting System (NNDRS) of China for analysis. Incidences of AHB were calculated by gender and age group using population denominators from the 2000, 2010, and 2020 censuses. Joinpoint regression was employed to evaluate trends, and an age-period-cohort model was used to assess the age, period, and cohort effects.

The annual average incidence of reported AHB in children aged 14 years and below in low, intermediate, and high endemic areas decreased from 1.65, 2.33, and 2.56 per 100,000 in 2005-2010 to 0.56, 0.58, and 0.48 per 100,000 in the 2016-2021 period. The 15-39-year age group in high endemic areas exhibited the most significant decline in incidence, dropping from 23.14 per 100,000 in 2005 to 4.59 per 100,000 in 2021 among males and from 10.62 per 100,000 to 3.21 per 100,000 among females. Age-period-cohort analysis indicated decreasing age, period, and cohort effects for reported AHB incidence in each endemic area, except for a slight upward trend in the 15-19-year age group and in the cohort born between 1951 and 1955.

This study demonstrated a rapid decline in AHB incidence across various endemic areas since 2005. Children aged 14 years and below exhibited very low AHB incidences, while the incidence among individuals over 15 years was higher. To further reduce AHB incidence, hepatitis B vaccine (HepB) coverage should be enhanced among adolescents and adults.