Factors influencing scar formation following Bacille Calmette-Guérin (BCG) vaccination

The prevalence of scar formation following Bacille Calmette-Guérin (BCG) vaccination varies globally. beneficial off-target effects BCG are proposed to be stronger amongst children who develop a scar. Within an international randomised trial (‘BCG reduce the impact coronavirus disease 2019 (COVID-19) in healthcare workers’; BRACE Trial), this nested prospective cohort study assessed and factors influencing formation, as well participant perception scarring 12 months vaccination. Amongst 3071 BCG-recipients, 2341 (76%) developed Scar was lowest Spain highest UK. Absence post-injection wheal (OR 0.4, 95%CI 0.2–0.9), revaccination 1.7, 1.3–2.0), female sex 2.0, 1.7–2.4), older age 0.4–0.5) country (Brazil OR 1.6, 1.3–2.0) influenced prevalence. Of participants with scar, 1806 (77%) did not mind having Participants more likely were those Brazil, males prior history. majority (96%) regret vaccine.Both vaccination-related (amenable optimisation) individual-related affected adults, implications for maximising effectiveness