Changes in seroprevalence of hepatitis A after the implementation of universal childhood vaccination in Shandong Province, China: A comparison between 2006 and 2014

Abstract

Objectives: The hepatitis A vaccine (HepA) has been included in the national expanded program on immunization (EPI) in China since 2008. This study was performed to evaluate the change in dynamics of the seroepidemiology of hepatitis A virus (HAV) before and after the introduction of the program. Methods: The trends in seroepidemiology of anti-HAV antibodies were examined in Shandong Province, China, drawing on two population-based samples of persons aged 1-59 years, one obtained in the year 2006 (n = 6682) and the other in 2014 (n = 5095). Results: A dramatic increase in seroprevalence of anti-HAV antibodies from 30.76% (95% confidence interval (CI) 26.24-35.28%) to 77.46% (95% CI 74.04-80.87%) among children aged 1.5-7 years (born after HepA was recommended for routine childhood immunization), as well as an increase from 35.32% (95% CI 29.31-41.33%) to 66.69% (95% CI 55.59-77.80%) in subjects aged 8-14 years, was observed in 2014 when compared with 2006. By contrast, a decline in seroprevalence among subjects aged 15-29 years, as seen particularly in those 20-29 years of age, from 85.72% (95% CI 80.29-91.14%) to 69.24% (95% CI 62.02-76.45%), was found in this study. There was no statistically significant difference in seroprevalence between 2006 and 2014 among the subjects older than 30 years of age. Conclusions: The national HepA routine immunization program has had a positive effect, leading to an increase in anti-HAV seroprevalence among children in Shandong Province, China. More attention should be paid to young adults in the province.

Changing Epidemiology of Hepatitis A in China: Evidence From Three National Serological Surveys and the National Notifiable Disease Reporting System

“…( 6,11,12 ) Coverage of children born between 2008 and 2012 was over 90%. This high national coverage has been stable over the years and is comparable with province‐level studies ( 13,14 ) and coverage levels seen in other countries, such as the United States, ( 15 ) Israel, ( 16 ) and Argentina. ( 17 ) In China, even though HepA vaccines had been available in the private sector since 1992, HepA coverage was low before the HepA vaccine was introduced nationwide in 2008, especially among adolescents and young adults born between 1984 and 1999.…”

“…From 1992 to 2006, with the rapid development of China's social economy, hygienic and sanitary conditions improved significantly, and the risk of natural HAV infection was reduced, resulting in lower HAV seroprevalence levels in children and young adolescents. (13,14) Rapid declines could be seen among 5-24-year-olds in both male and female individuals, in rural areas, and in the Central and Western regions of the country.…”

Hepatitis A vaccination and its immunological and epidemiological long-term effects – a review of the evidence

“… 160 These UMV effects lead to an, at first glance, ”uncoordinated” looking shift in seroprevalence, with seroprotection rates increasing for the young age groups and initially decreasing or leveling off for the adolescents and young adults, while high infection-induced seropositivity remains for the rest of the older adult population. A few reports on serological long-term effects of UMV have shown this seroprevalence pattern for the US, 172 Italy, 163 China 153 (see also Table 5 ) and Israel. 184 Furthermore, a population-based study from Israel typically shows how difficult it is to interpret the serological data 12 years after successful implementation of toddler vaccination, i.e.…”

“…139,145 Similar data were reported for regional UMVs regarding disease incidence, 86,152,154 outbreak frequency, 158 and regarding hospitalizations. 166 Other epidemiological parameters indicating nationwide or regional success or expected effects of UMV were: herd protection of untargeted age groups 22,146,147,149,154,160 (section 4.2), a rise in seroprotection rates in targeted children/adolescents 153 or young adults, 161 susceptibility (seronegativity) shift toward older age groups, 163,172 a disease burden shift toward older age, 154,156,[171][172][173][174] international travel becoming a predominant risk factor for HAV transmission, 171,172 a decline in the rate of infection-induced high anti-HAV levels in non-vaccinated toddlers, 159 a declining rate of HAV among all viral hepatitis cases 151 and finally, declining HAV positivity of river water samples. 144 To sustain HAV elimination, a certain vaccination coverage of the pediatric target population should be maintained.…”

“…f – 2000 vs 2011 2.89 → 0.12 (95.9% ↓) Rate of HAV among all viral hepatitis cases: 8.02 → 0.45% Tianjin city Sun (2018) 22 2008 18 months 18 months Single-dose Live-atten. f Two-dose Inactivated 98.7% 99.6% 2004 vs 2016 2004 vs 2016 7.5 → 1.7 (77.4% ↓) 3.9 → 0.7 (82.3% ↓) Strong herd immunity effect seen from 2008 →2016 in both L-HepA i and I-HepA i regions Separate evaluation of L-HepA and I-HepA regions Wang (2019) 152 1994 18/24 months Two-dose inactivated > 99% j 1990 → 2017 59.4 → 0.80 (98.6% ↓) Incidence 2004 → 2017 by age: - 2.52 → 0.06 for age < 10 years - 1.96 → 0.26 for age 10–20 years - 3.27 → 0.91 for age > 20 years City of Bejing only Yan (2019) 153 2008 18 months 18/24 months Single-dose live-atten. Two-dose inactivated > 99% (2014) 2006 vs 2014 – Seroprevalence change by age: - 30.8% → 77.5% age 1.5–7 years - 35.3% → 66.7% age 8–14 years - 85.7% → 69.2% age 20–29 years - No difference for age ≥ 30 years Shandong province Guo (2020) 154 2008 18 months Single-dose Live-atten.…”