Abstract
Since August 2012, universal single-dose vaccination in children aged at least three years has been implemented in the Republic of Tuva, which was previously the region most affected by hepatitis A in Russia. The objective of this cross-sectional study was the assessment of the immunological and epidemiological effectiveness of vaccination program five years following its implementation. In the pre-vaccination period, anti-HAV antibody detection rates in Tuva was 66.0% [95% CI: 56.3–74.6%] in children aged 10–14 years and reached a plateau (>95%) by age 20–29 years. Annual incidence rates in children under 18 years of age peaked at 450–860 per 100,000 in pre-vaccination years but dropped to 7.5 per 100,000 in this age group and to 3.2 per 100,000 in the total population one year after the start of vaccination. Since 2016, no cases of hepatitis A has been reported in Tuva. Serum anti-HAV antibodies were quantified in samples from healthy children following single-dose vaccination. Protective anti-HAV antibody concentrations (≥10 mIU/mL) were detected in 98.0% (95% CI: 96.2–99.0% (442/451)) of children tested one month after single-dose immunization, in 93.5% (95% CI: 91.0–95.4% (477/510)) and in 91.1% (95% CI: 88.2–93.4% (422/463)) of children one year and five years after single-dose immunization, respectively. Anti-HAV antibody geometric mean concentrations were similar in sera collected one month, one year, and five years following single-dose vaccination: 40.24 mIU/mL, 44.96 mIU/mL, and 57.73 mIU/mL, respectively (p > 0.05). These data confirm that single-dose vaccination is an effective method of bringing hepatitis A under control in a short period of time in a highly endemic region.
Highlights
Hepatitis A is a disease preventable by vaccination
We present the data on the herd immunity to hepatitis A virus (HAV) in Tuva in pre-vaccination period to give a more comprehensive epidemiological characterization of the study region
Incidence rates registered in Tuva in 2013–2019 were compared to those observed in the pre-vaccination period, both for the total population and for children under 14 years
Summary
Hepatitis A is a disease preventable by vaccination. There are two types of vaccines against hepatitis A—live attenuated vaccines, adopted in China [1], and inactivated vaccines that are available worldwide [2]. As children typically exhibit asymptomatic hepatitis A infection, this leads to an overall increase in the number of clinically significant and severe cases of the disease [3] For countries experiencing this kind of epidemiological shift, where the disease burden is greatest, the World Health Organization (WHO) recommends implementation of universal vaccination programs [4]. Several countries introduced universal two-dose vaccination against hepatitis A in national immunization schedules for children aged ≥1 year (Israel, Panama, Uruguay, and 17 states of the USA). This resulted in a rapid 93–98% decline in disease incidence [2]
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