Postmarketing safety of vaccines approved by FDA

A retrospective cohort study examined FDA-approved vaccine labels and subsequent labeling changes triggered by post-market safety concerns. The research, covering a period of 20 years ending in December 2015, included 57 vaccines—most of which were supported by large randomized controlled trials. Investigators determined that 25 of the vaccines later added 58 different warnings, contraindications, or other safety-related modifications. These updates most often were based on postmarketing surveillance, and the primary safety issues prompting them were expansion of population restrictions and allergic reactions. Most safety concerns had little clinical significance, however, and the study authors concluded that vaccines in general are “remarkably safe” and that the vaccine approval system, in tandem with postmarketing surveillance, works.