BCG Revaccination
While early evidence suggested that revaccination does not increase the protective efficacy of BCG vaccine, there have been strong indications lately that it is possible to increase the immune response by a second dose of BCG vaccine. Various BCG vaccination schedules have been re-evaluated in recent research clinical trials (CLT) due to high numbers of TB cases and deaths. The paradigm-establishing 1968 Chingleput/India BCG vaccination trial has been challenged, and a retrospective data analysis of this community-based CLT revealed that revaccination offered modest protection against TB. Similar to protection status, the rate of adverse events (AEs) following revaccination with BCG varies globally, but earlier CLTs concluded that revaccination carries minimal risk. Future CLT of the BCG vaccine should report AE occurrences, since a small increase in the rate of mild local and systemic reactions has been observed. With these issues in mind, this Collection of original articles (i) presents new findings to keep readers updated regarding BCG revaccination, and (ii) provide a forum to debate what is known about BCG vaccine AEs. Earlier reports clearly reinforce the importance of conducting additional CLT to characterize immune response profiles leading to protection against TB and of immunization schedules relative to BCG vaccine AEs with the goal to deriving a better safety protocol with revaccination.
Edited by
Paulo Antas(Fundação Oswaldo Cruz, Fiocruz, Brazil ([email protected]))