Seroprotection Rates After Late Doses of Hepatitis B Vaccine

We read with interest the recent article by Middleman et al.1 It shows what we can expect from a clinic-based hepatitis B program targeting adolescents. However, we were quite deluded of the analysis of data. Indeed, several questions emerged after the reading: 1. Why did they not analyze the time elapsed between last dose and anti-HBs antibody titers? From what we can deduce from the text, that interval could be as short as 3 months for some people and as long as 18 months for others (since first follow-up was between 11 and 22 months and some people got only 1 or 2 shots). It is well-known that the antibody titer decays over time. That variable was one of the most important to study or at least to control. Why did they not introduce it as a continuous variable in their analysis model? 2. One can conclude from the data presented that a …