Johnson & Johnson’s Ad26.COV2.S vaccine

A single dose of Johnson & Johnson’s Ad26.COV2.S vaccine appears to be safe and induce an immune response in two age groups, according to interim results of a phase 1-2a trial published in the New England Journal of Medicine.

A total of 800 adults aged 18 to 55 or aged 65 and up were randomized to various combinations of low-dose or high-dose vaccines or placebo, given 56 days apart.

Adverse events were common, with fatigue, headache, myalgia, and injection-site pain reported most often. At day 29 after the first dose, the seroconversion rate was 99% or more in the younger cohort across dosing groups. Older vaccine recipients had a 96% seroconversion rate. At 57 days after the first dose, antibody titers had increased further.

NEJM article on Johnson & Johnson vaccine