COVID-19: J&J single-shot vaccine shows acceptable safety, high reactogenicity in phase 1-2a

  • Sadoff J & al.
  • N Engl J Med
  • 13 Jan 2021

  • curated by Miriam Davis, PhD
  • Clinical Essentials
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Takeaway

  • The interim results of a phase 1-2a trial of Johnson & Johnson (J&J)'s adenovirus-vectored double-stranded DNA vaccine indicate acceptable safety and high reactogenicity even after a single dose.

Why this matters

  • A single-dose vaccine would be easier to administer than the currently available 2-dose vaccines.
  • The company's phase 3 ENSEMBLE trial of the single dose is ongoing.

Study design

  • Multicenter, placebo-controlled randomized trial, 805 participants stratified by age: 18-55 years and ≥65 years.
  • Low-dose vaccine (5×1010 viral particles) and high-dose (1×1011 viral particles) were administered in single or double doses.
  • Neutralizing antibodies and CD8+T-cell responses were used to evaluate reactogenicity.
  • Funding: Johnson & Johnson; Biomedical Advanced Research and Development Authority of the US Department of Health and Human Services.

Key results

  • Neutralizing antibodies were seen in >90% of both cohorts given single or double doses by day 29 and remained stable until day 57.
  • T-cell responses were higher in the younger cohort (76%-83%) than in the older cohort (60%-67%).
  • The most frequent local adverse events were fatigue, headache, myalgia, and injection-site pain.
  • The most frequent systemic adverse event was fever (highest rate was 39% of the younger cohort receiving the high-dose vaccine), which resolved within 1-2 days.

Limitations

  • Effect of vaccine on avoiding infection was not studied.