Repeat vaccination with the bacille Calmette-Guérin (BCG) vaccine was safe in adults during the convalescent period of COVID-19 infection, according to results of a study published in Vaccine.
This multicenter, prospective, double-blinded, placebo-controlled study was conducted at 2 outpatient health systems in Brazil. Adults (N=299) who tested positive for SARS-CoV-2 infection were randomly assigned in a 1:1 fashion to receive either the BCG vaccine (n=148) or placebo (n=151). Using a questionnaire, the researchers evaluated the incidence of adverse events (AEs) on days 7, 14, and 21 after vaccine administration, as well as those that occurred after day 40.
Among patients included in the vaccine and placebo groups, the mean age was 40.4 and 42.8 years, 58.1% and 63.6% were women, 79.7% and 80.8% had symptomatic COVID-19 infection, 93.9% and 92.7% had a childhood BCG scar, and 6.8% and 1.3% had chronic pulmonary disease (P =.039), respectively.
The most common COVID-19 symptoms among the patients were anosmia (44.5%), ageusia (36.1%), fatigue (33.1%), cough (32.1%), and headache (20.7%).
Compared with patients in the placebo group, those who received the BCG vaccine were more likely to report dyspnea at day 7 (odds ratio [OR], 0.31; 95% CI, 0.07-1.05; P =.042) and fatigue at day 21 (OR, 0.36; 95% CI, 0.13-0.89; P =.017), and they were less likely to report anosmia at day 7 (OR, 1.70; 95% CI, 1.01-2.89; P =.035).
In a sensitivity analysis in which adults with chronic pulmonary disease were excluded, the difference in the number of reported dyspnea (OR, 0.31; 95% CI, 0.07-1.11; P =.061) and fatigue (OR, 0.53; 95% CI, 0.23-1.17; P =.10) events was no longer significant between the 2 patient groups.
The researchers noted that skin lesions at the injection site occurred among most patients (87.8%) in the vaccine group. The lesions had a mean size of 10.6±6.4 mm, which subsequently decreased to a mean size of 6.8 mm by day 40. For a minority of patients (4.7%) in the vaccine group the lesions turned into a small ulcer 3 weeks following vaccination, with a maximum mean size of 8.7±2.5 mm. Lesions were local erythema in 82.4% of patients, papules in 62.8%, and pustules in 8.1%. Other AEs among patients in the vaccine group included mild itching (12.8%) and local pain (6.1%).
No severe AEs were reported by patients in either group.
This was limited by its relatively small sample size, as well as the inherent difficulty in blinding patients in the vaccine group who experienced vaccine-related skin lesions.
According to the researchers, “BCG revaccination is unlikely to cause serious [AEs] in…adults [during the convalescent period of COVID-19].”
Dionato FAV, Jalalizadeh M, Buosi K, et al. BCG vaccine safety in COVID-19 convalescent adults: BATTLE a randomized controlled trial. Vaccine. 2022;S0264-410X(22)00803-9. doi:10.1016/j.vaccine.2022.06.039