Adverse events of active and placebo groups in SARS-CoV-2 vaccine randomized trials: A systematic review

Abstract (PubMed)

Adverse events (AEs) are reported for the drug under evaluation and compared with AEs in the placebo group. Little is known about the nature of the AEs associated with clinical trials of SARS-CoV-2 vaccines and the extent to which these can be traced to nocebo effects, where negative treatment-related expectations favor their occurrence. Systematic review of 3 phase III trials (BNT162b2, mRNA-1273, Ad26.COV2.S) comprising 45,139 participants. Most common AEs: local pain (79-84% vaccine vs 12-17% placebo), fatigue (37-42% vs 27-29%), headache (33-35% vs 27%), myalgia (18-23% vs 10-14%). A substantial proportion of AEs in the vaccine groups may be attributable to nocebo effects rather than the vaccines themselves.