Estimating sero-protection rate after delayed doses of hepatitis B vaccination in the wake of COVID-19 pandemic

Introduction: Vaccination against hepatitis B virus (HBV) is safe and very effective in preventing HBV infection and its complications. The currently available HBV vaccine preparations use recombinant hepatitis B surface antigen (HBsAg) as the antigen. Large vaccination studies suggested non-responder rates in the range of 5–10%. This study aims to estimate the difference in non-response rate after delayed doses of Hepatitis B vaccination in the wake of the COVID-19 pandemic. Methods: A total of 250 students enrolled during the academic year 2020–21 were selected for the study. The study participants were tested for anti-HBs-IgG titers one–two months post the third dose of vaccine by electro-chemiluminescent immunoassay method and the vaccination response were documented. Results: The 246 (98.4%) participants had anti-HBs titers >100 IU/L (range 2444–3612 IU/L) with a median titer of 2826 IU/L; and 4 (1.6%) participants had titers between 10 and 99 IU/L (low responders). There were none who had antibody titers <10 IU/L (non-responders). Discussion: It was found that the vast majority (98.4%) of the study participants who received a delayed third dose of HBV vaccine developed good sero-protection against HBV infection and the low responder rate was 1.6%. In our cohort, intervals up to 18 months (1.5 years) between the first and third dose were not associated with a decline in the sero-protection rate. Conclusion: The response to Hepatitis B vaccine is not highly dependent on the timing of vaccine doses and modest alterations in the timing of doses do not affect the excellent response to this vaccine.