In this study, the Australian authors investigated the heterologous and specific immunological effects of vaccination in children aged 5 to 11 years who received two doses of BNT162b2 COVID-19 vaccine (Pfizer, USA). The results showed that SARS-CoV-2 mRNA vaccine alters cytokine responses to heterologous stimulants (killed pathogens, Toll-like receptor agonists, and SARS-CoV-2 antigens) in children, and that these effects can persist for up to six months after vaccination.

About the study

The COSI BAIR was a single-arm clinical trial in which all participants received two doses of BNT162b2 vaccine (Pfizer, USA), 8 weeks apart. COSI BAIR participants were a subgroup of the Melbourne Infant Study: BCG for Allergy and Infection Reduction (MIS BAIR) randomized controlled trial. The aim of the MIS BAIR study was to investigate whether neonatal BCG vaccination can protect children from infections, allergies, and asthma in childhood. Neonates were randomly assigned to receive or not receive the BCG vaccine in the first 10 days of life. Participants from both groups were recruited for the COSI BAIR study.