HBV Catch-up Vaccination in Children and Adults with Incomplete or Unknown Vaccination to Reduce Hepatitis B-related Morbidity: A Systematic Review.

Abstract

<h4>Background</h4>Hepatitis B virus causes life-threatening chronic liver infection and increases the risk of death from cirrhosis and liver cancer. A three-dose series of universal HBV vaccination initiated from birth is effective against the disease. It is unclear if catch-up vaccination is also effective in those with incomplete or no HBV vaccination.<h4>Objective</h4>To review the evidence on the effect of HBV catch-up vaccination on children and adults to decrease HBV-related morbidity.<h4>Methods</h4>We searched MEDLINE, Cochrane CENTRAL, ChinaXiv, MedRXIV, BioRXIV, Google Scholar, and ongoing and completed trials on USA: https://clinicaltrials.gov/; China: http://www.chictr.org.cn/searchprojen.aspx, and WHO: https://www.who.int/clinical-trials-registry-platform. The last search date was 30 June 2023. We considered experimental or observational studies, meta-analysis/systematic reviews, completed trials and preprints that investigated the efficacy of catch-up HBV immunization in decreasing morbidity from hepatitis B infection including acute and chronic hepatitis B infection, liver cirrhosis, and hepatocellular carcinoma. There was no age and language restriction. Two reviewers independently rated the quality of included studies using Newcastle - Ottawa Quality Assessment Scale for cohort and cross-sectional studies. GRADE (Grading of Recommendations, Assessment, Development and Evaluations) approach was used to determine the certainty of evidence. Data was presented as number (%) for categorical values. Differences between the unvaccinated and vaccinated group was described as relative risk or odds ratio for categorical variables. Data was pooled using Review Manager 5.4.<h4>Results</h4>A total of four observational studies were included, one of which had data in children and adults [two (one with data in adults) studies in children; 3 in adults]. The cross-sectional study was assessed as good quality; and the three cohorts as fair to good. In children, a high certainty evidence study showed that catch up vaccination in 9 to 18 years old decreased risk of HBsAg positivity [RR: 0.09 (0.004, 0.21)], reduced HBV DNA detection [RR: 0.084 (0.026, 0.273)], and increased anti-HBs seroconversion [RR: 2.08 (1.84, 2.33)]. The quality of evidence was deemed high based on a large treatment effect. Another low certainty evidence study in Italy showed that HBV mass immunization in 0-10 years old decreased the prevalence of HBsAg anti-HBc and increased anti-HBs seroconversion after vaccination. In adults, three low certainty evidence studies were included. Two studies showed decreased incidence of acute hepatitis B [OR: 0.08 (0.05, 0.12), I2 = 33%]. Another study demonstrated a decreased prevalence of hepatocellular carcinoma with HBV vaccination with the incidence ratio of vaccinated with chronically infected at 0.04 (0.02, 0.07) showing a large magnitude of benefit for vaccination against HCC when chronic HBV infection is prevented. The studies were deemed to have low quality due to issue of directness and study design.<h4>Conclusion</h4>HBV catch-up vaccination in adults is effective in decreasing the prevalence of acute hepatitis B and hepatocellular carcinoma. It likewise decreased the prevalence of HBsAg and anti-HBc, and provided anti-HBs protection in 0 to 18 years.