Tehran University of Medical Sciences Iranian Journal of Public Health 2251-6085 51 10 2022 10 04 2181 2193 SasidharanPillai Sabeena Clinical Virology, Allure Residency, Near the British School, Kathmandu, Nepal Nagaraja Ravishankar Department of Biostatistics, Vallabhbhai Patel Chest Institute, University of Delhi, New Delhi, India 2021 09 17 2021 11 02 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. https://ijph.tums.ac.ir/index.php/ijph/article/view/26307 https://ijph.tums.ac.ir/index.php/ijph/article/download/26307/7736