Neutralizing antibodies detected in 90 percent or more of all participants on day 29 after the first vaccine dose<\/p>\n<\/h3>\n
<\/b><\/p>\n
<\/b><\/p>\n
WEDNESDAY, Jan. 13, 2021 (HealthDay News) — A candidate vaccine, Ad26.COV2.S, with a recombinant, replication-incompetent adenovirus serotype 26 (Ad26) vector encoding a full-length and stabilized severe acute respiratory syndrome coronavirus 2 spike protein is safe and immunogenic, according to a study published online Jan. 13 in the New England Journal of Medicine<\/em>.<\/p>\n Jerald Sadoff, M.D., from Janssen Vaccines and Prevention in Leiden, Netherlands, and colleagues conducted a phase 1-2a trial involving healthy adults ages 18 to 55 years (cohort 1) and 65 years or older (cohort 3). Participants were randomly assigned to receive Ad26.COV2.S at a low dose or high dose or placebo in a single-dose or two-dose schedule.<\/p>\n The researchers found that the most frequent adverse events were fatigue, headache, myalgia, and injection-site pain after administration of the first vaccine dose in 805 participants in cohorts 1 and 3 and after the second dose in cohort 1. Fever was the most frequent systemic adverse event. Systemic adverse events were less common in cohort 3 versus 1 and for those who received a low versus high dose. On day 29 after the first vaccine dose, neutralizing antibody titers against wild-type virus were detected in 90 percent or more of all participants; this level reached 100 percent by day 57, with a further increase in titers irrespective of vaccine dose or age group. Until at least day 71, the titers remained stable. An increase in the titer by a factor of 2.6 to 2.9 was seen with a second dose. Spike-binding antibody responses were similar to those of neutralizing antibodies.<\/p>\n “Our interim analysis indicates that vaccine candidate Ad26.COV2.S is safe and immunogenic in both younger and older adults,” the authors write.<\/p>\n The study was funded by Johnson & Johnson, the manufacturer of the Ad26.COV2.S vaccine.<\/p>\n