Horizontal Modes of Transmission of Hepatitis B Virus (HBV): A Systematic Review and Meta-Analysis.

Background: Horizontal transmission of hepatitis B virus (HBV) is a significant transmission route in households, among contact sport athletes and institutionalized individuals. Children often are infected by non-sexual close contacts with an increased tendency to become chronic carriers. Hence, the awareness about various high-risk behaviours leading to horizontal transmission in the community is essential. A systematic review and meta-analysis was carried out to assess quantitatively the pooled prevalence of horizontally transmitted HBV infection globally. Methods: The study was started after ruling out registered or ongoing systematic reviews related to this topic in the PROSPERO database. The study protocol was documented in PROSPERO with a registration number CRD42021235165. We searched electronic databases for published articles in English between 1981 and April 2021 reporting horizontal modes of hepatitis B transmission among unvaccinated contacts. Meta-analysis was carried out in STATA version 13.0 (College Station, Texas 77,845 USA). The forest plots were constructed using metaprop package in STATA. Results: Forty-one studies were systematically reviewed and 15 studies were qualified for the meta-analysis, including 1619 hepatitis B cases and 4869 contacts. The overall pooled prevalence of horizontally transmitted HBV infection among the contacts was 38% (95% CI 30%-46%). The pooled prevalence among 3,912 household contacts from nine qualified studies was estimated as 44% (95% CI 35%-54%). The pooled prevalence rates among institutionalized individuals and contact sport athletes were 30% (95% CI 23%-37%) and 18% (95% CI 5%-32%), respectively. Conclusion: The likelihood of horizontal transmission of HBV is greater among household contacts of chronic carriers of HBV and institutionalized individuals.