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Final Analysis of Efficacy and Safety of Single-Dose Ad26.COV2.S

  • J. Sadoff
  • , G. Gray
  • , A. Vandebosch
  • , V. Cárdenas
  • , G. Shukarev
  • , B. Grinsztejn
  • , P. A. Goepfert
  • , C. Truyers
  • , I. Van Dromme
  • , B. Spiessens
  • , J. Vingerhoets
  • , J. Custers
  • , G. Scheper
  • , M. L. Robb
  • , J. Treanor
  • , M. F. Ryser
  • , D. H. Barouch
  • , E. Swann
  • , M. A. Marovich
  • , K. M. Neuzil
  • L. Corey, J. Stoddard, K. Hardt, J. Ruiz-Guiñazú, M. Le Gars, H. Schuitemaker, J. Van Hoof, F. Struyf, M. Douoguih*
*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

198 Scopus citations

Abstract

BACKGROUND The Ad26.COV2.S vaccine was highly effective against severe critical coronavirus disease 2019 (Covid-19), hospitalization, and death in the primary phase 3 efficacy analysis. METHODS We conducted the final analysis in the double-blind phase of our multinational, randomized, placebo-controlled trial, in which adults were assigned in a 1:1 ratio to receive single-dose Ad26.COV2.S (5×1010 viral particles) or placebo. The primary end points were vaccine efficacy against moderate to severe critical Covid-19 with onset at least 14 days after administration and at least 28 days after administration in the per-protocol population. Safety and key secondary and exploratory end points were also assessed. RESULTS Median follow-up in this analysis was 4 months; 8940 participants had at least 6 months of follow-up. In the per-protocol population (39,185 participants), vaccine efficacy against moderate to severe critical Covid-19 at least 14 days after administration was 56.3% (95% confidence interval [CI], 51.3 to 60.8; 484 cases in the vaccine group vs. 1067 in the placebo group); at least 28 days after administration, vaccine efficacy was 52.9% (95% CI, 47.1 to 58.1; 433 cases in the vaccine group vs. 883 in the placebo group). Efficacy in the United States, primarily against the reference strain (B.1.D614G) and the B.1.1.7 (alpha) variant, was 69.7% (95% CI, 60.7 to 76.9); efficacy was reduced elsewhere against the P.1 (gamma), C.37 (lambda), and B.1.621 (mu) variants. Efficacy was 74.6% (95% CI, 64.7 to 82.1) against severe critical Covid-19 (with only 4 severe critical cases caused by the B.1.617.2 [delta] variant), 75.6% (95% CI, 54.3 to 88.0) against Covid-19 leading to medical intervention (including hospitalization), and 82.8% (95% CI, 40.5 to 96.8) against Covid-19 related death, with protection lasting 6 months or longer. Efficacy against any severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection was 41.7% (95% CI, 36.3 to 46.7). Ad26.COV2.S was associated with mainly mild-to-moderate adverse events, and no new safety concerns were identified. CONCLUSIONS A single dose of Ad26.COV2.S provided 52.9% protection against moderate to severe critical Covid-19. Protection varied according to variant; higher protection was observed against severe Covid-19, medical intervention, and death than against other end points and lasted for 6 months or longer. (Funded by Janssen Research and Development and others; ENSEMBLE ClinicalTrials.gov number, NCT04505722.)

Original languageEnglish
Pages (from-to)847-860
Number of pages14
JournalNew England Journal of Medicine
Volume386
Issue number9
DOIs
StatePublished - 3 Mar 2022

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