IMZ and LMAH collected and analysed the data. IMZ, RR, LMAH, RMCH, MCJMS, SMJMS and BHS participated in the development and critical review of the manuscript for important intellectual content and provided the final

approval of the version to be published. Funding: This study was supported by the Drug Safety Unit of the Dutch Inspectorate of Health Care. Competing interests: LMAH and RMCH are employees of the PHARMO Institute. This independent research institute performs financially supported studies for government and related healthcare authorities and several pharmaceutical companies. MCJMS is leading a research group that sometimes conducts research for pharmaceutical companies. Provenance and peer review: Not commissioned; externally peer reviewed. Data sharing statement: No additional data are available.
Four hundred million people in the world are living with chronic hepatitis B virus (HBV) infection.1 The majority of these individuals acquired the infection during the perinatal period

and early childhood.2 The risk of becoming a chronic hepatitis B infection carrier is 95% for infections acquired during the perinatal period3 compared with only 5% for those acquired during adulthood.4 Up to 50% of HBV carriers die of complications including liver cirrhosis and hepatocellular carcinoma.5 Pregnant mothers who test positive for both hepatitis B surface antigen (HBsAg) and hepatitis B e antigen (HBeAg) have 70–90% risk of transmitting infection to their newborn infants and about 10–40% risk if they test positive for only HBsAg.5 6 Therefore, pregnant women should be routinely screened for HBsAg and hepatitis B vaccine administered at birth to the infants whose mothers test positive.7 8 However, this is not the practice in Uganda. The Uganda National Expanded Program on Immunizations (UNEPI) scaled-up childhood immunisations in 20029 incorporated the hepatitis B vaccine into a combination vaccine

whose first dose is administered at 6 weeks of age. The 6 weeks window both limits the efficacy of the vaccine in the prevention of vertical transmission and also allows for the potential transmission of HBV through close contacts.7 The most effective method of preventing HBV infection is through immunisation, which offers over 95% protection against the development of chronic infection.10 Such immunisation should be done at birth for exposed infants. There is no evidence of protection against perinatal transmission if the first dose of vaccine is given more than 7 days after birth.11 In Nigeria, Cilengitide the prevalence of HBV infection among pregnant women was 11% with an HbeAg positivity of 33%.12 In northern Uganda, there is limited knowledge on the prevalence of hepatitis B infection among pregnant women. The civil war in this region between the government of Uganda and the Lord’s resistance army from the late 1980s up to 2006 led to the displacement of as many as 1.7 million people from their homes into internally displaced persons camps.