. 2020 Nov 10;181(4):559–560. doi: 10.1001/jamainternmed.2020.7472

Table 2. Features of the Aggregated Pivotal Efficacy Trials Supporting 21 Vaccines Approved by the FDA From 2010 to 2020.

Feature	Median (IQR)
Total enrolled patients^a	4961 (3537-7775)
Total patients in intervention group^a	3552 (2398-4561)
≥1 Pivotal trial, No. (%)
With randomization	21 (100.0)
With masking	17 (81.0)
With active/placebo comparator	20 (95.2)
With clinical primary end point^b	8 (38.1)
Vaccine efficacy, %^c	91.9 (79.6-98.0)

Abbreviations: FDA, US Food and Drug Administration; IQR, interquartile range.

^{^a}

Values represent the total number of patients across all pivotal efficacy trials supporting FDA approval of given vaccine.

^{^b}

Clinical primary end points represent the rate of laboratory-confirmed infection. The remaining 13 vaccine approvals were based on antibody immune response.

^{^c}

Calculated among the 8 vaccines approved on the basis of a clinical primary end point. For vaccines with multiple pivotal efficacy trials using a clinical primary end point, the pooled vaccine efficacy was used. For Gardasil 9 (Merck), vaccine efficacy was only reported for human papillomavirus types 31, 33, 45, 52, and 58 because types 6, 11, 16, and 18 had an existing vaccine (Gardasil) that was used as a comparator in the pivotal efficacy trial.