- 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.
- 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.
- 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.
- Effect of vaccine on avoiding infection was not studied.