Johnson & Johnson’s single-shot, adenovirus vector Covid-19 vaccine seems safe and effective, with 100% efficacy for preventing severe disease and death, according to the FDA.
While vaccine efficacy varied from country to country and was markedly lower in adults age 60 years and older with comorbidities, the FDA’s review concluded that the Ad26.COV2.S vaccine has an overall global efficacy of 66% — lower than the efficacy for the Pfizer and Moderna mRNA vaccines, but still well above the FDA’s bar of at least 50% efficacy required for authorization — and a favorable safety profile, “with no specific safety concerns identified that would preclude issuance of an EUA,” the agency wrote.
The FDA laid out its review of the Ad26.COV2.S vaccine in a briefing document published Wednesday ahead of the Vaccines and Related Biological Products Advisory Committee (VRBPAC)’s Feb. 26 meeting to discuss whether the vaccine should receive an emergency use authorization (EUA) for individuals 18 years and older. If authorized, Ad26.COV2.S will become the third Covid-19 vaccine authorized for emergency use in the U.S.
In its briefing document, the FDA reported that the Ad26.COV2.S vaccine was 72% effective among patients in the U.S. at 28 days post-vaccination — however, efficacy dropped to 64% and 61% in South Africa and Latin America, respectively, where Covid-19 variants accounted for the majority of cases (B.1.351 in South Africa; P.2 in Brazil).
Notably, Ad26.COB2.S had an overall efficacy of 85.4% for preventing severe disease — and there were no Covid-19 cases requiring hospitalization or mechanical intervention in the vaccine group at 28 days post-vaccination. What’s more, while Johnson & Johnson reported seven Covid-19 related deaths in the study, all seven occurred in the placebo group. These results were similar across all countries included in the analysis.
The FDA also noted that vaccine efficacy among study subgroups was similar to that in the overall study population, save for one subgroup: patients 60 years and older with comorbidities such as hypertension, diabetes, or obesity saw a vaccine efficacy of only 42.3% at 28 days post-vaccination. However, the FDA added, vaccine efficacy estimates increased when the number of cases included in the analysis increased, suggesting that this reduced efficacy may “reflect imprecision associated with smaller numbers of cases.”
As for adverse reactions to the vaccine, the FDA noted that reactogenicity appeared transient across the board, with most solicited adverse events resolving within one to two days. The most commonly reported adverse reactions were injection site pain (48.6%), headache (38.9%), fatigue (38.2%), and myalgia (33.2%), and the majority of reactions were reported as mild or moderate. Reactions were more frequent among younger participants than older — for example, injection site pain was reported among 58.6% of patients age 18-59 years in the vaccine group compared to 33.3% of patients age ≥60 years — a finding that is consistent with the slightly reduced efficacy among older vaccine recipients.
Despite these positive results, the VRBPAC briefing document also pointed out several remaining questions regarding the Ad26.COV2.S vaccine, including duration of protection against SARS-CoV-2, efficacy in immunocompromised and pediatric patients who were not included in early analyses, efficacy against asymptomatic infection and long-term effects of Covid-19 disease, and efficacy in reducing rates of SARS-CoV-2 transmission. The FDA noted that questions such as these will need to be evaluated using clinical trial data and reports of vaccine use post-authorization.
John McKenna, Associate Editor, BreakingMED™
Cat ID: 190
Topic ID: 79,190,730,933,190,31,926,192,561,927,725,928,925,934
