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. 2023 Apr 6;9(4):e15241.
doi: 10.1016/j.heliyon.2023.e15241. eCollection 2023 Apr.

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

Affiliations

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

Paola Villanueva et al. Heliyon. .

Erratum in

Abstract

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

Keywords: BCG scar; BCG vaccine; Vaccination technique; Vaccine safety.

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Figures

Figure 1
Figure 1
BCG scar description at 12 months. Representative photographs for BCG scar descriptions. (A) skin colour mark without redness (normal scar formation), (B) red mark, (C) red mark with crusting, (D) red mark with discharge, (E) purple mark, (F) inflamed appearance with surrounding swelling and/or redness, (G) abnormal thick scar.
Figure 2
Figure 2
BRACE participants who received BCG in A) Stage 1 and B) Stage 2. Abbreviations: BCG, Bacille Calmette-Guérin; BRACE trial, BCG vaccination to reduce the impact of coronavirus disease 2019 (COVID-19) in healthcare workers; dTpa, diphtheria-tetanus-acellular pertussis vaccine, reduced antigen formulation; 12MQ, 12-month questionnaire.
Figure 3
Figure 3
BCG scar prevalence at 12 months by recruitment country, with 95% confidence interval.
Figure 4
Figure 4
Scar prevalence by vaccinator, grouped by study country. Proportion of scar positive vaccinees at 12 months, per vaccinator. Each data point represents an individual vaccinator. Horizontal lines represent medians.
Figure 5
Figure 5
BCG scar perception at 12 months by study country.

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