A case series of Bacillus Calmette-Guérin reactivation after
administration of both mRNA and viral vector COVID-19 vaccines
Abstract
Reactivation of the scar resulting from intracutaneous injection of
Bacillus Calmette-Guérin (BCG) is a common specific reaction in
Kawasaki’s Disease. It has also sporadically been associated with viral
infections, Multisystem Inflammatory Syndrome in Children, influenza
vaccination and mRNA COVID-19 vaccination. Since the start of the
COVID-19 vaccination campaign in January 2021, the Netherlands
Pharmacovigilance Centre Lareb has received 22 case reports of BCG
reactivation after vaccination with a COVID-19 vaccine. In 20 case
reports it concerned mRNA COVID-19 vaccines Moderna (14) and Pfizer (6).
In 2 case reports the viral vector COVID-19 vaccine AstraZeneca was
administered. Erythema and pain were the most frequently reported
symptoms and the size of the inflammation was between 1.5 to 5 cm. BCG
reactivation occurred with a median time to onset of 2 days after the
second or booster COVID-19 vaccination, whereas the median time to onset
was 7 days after the first COVID-19 vaccination. None of the BCG
reactivations were treated. The exact mechanism of the occurrence of
this specific reaction remains unknown, however involvement of heat
shock protein 65 is suggested. BCG reactivation is a non-serious,
self-limiting reaction that can occur after vaccination with both mRNA
and viral vector COVID-19 vaccines.