J&J's one-shot COVID-19 vaccine snags FDA staff's backing as panel review looms

J&J
The vaccine was 85% effective at preventing severe COVID-19 infection and kept people out of hospital at least 28 days after vaccination. (Raysonho/CC0)

Johnson & Johnson’s COVID-19 vaccine is one step closer to emergency authorization as FDA staffers endorsed it as safe and effective in briefing documents released (PDF) on Wednesday, ahead of an advisory committee meeting scheduled for Friday.

The documents confirmed the safety and efficacy profile of the vaccine, known as Ad26.COV2.S, reiterating that it was 66.1% effective at preventing COVID-19 infection at least 28 days after vaccination, with a “favorable safety profile” and “no specific safety concerns identified that would preclude issuance of an EUA.” The vaccine is given in a single injection and Johnson & Johnson is seeking an emergency nod in adults aged 18 and older.

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J&J’s request for Emergency Use Authorization is based on a phase 3 study testing the vaccine in about 44,000 patients in the U.S., Latin America and South Africa. The vaccine did better in the U.S., where it was 72% effective, but its overall efficacy was brought down by poorer performance outside the U.S.: 66% in Latin America and 57% in South Africa, where a new SARS-CoV-2 variant has spread. However, because the investigators haven’t completed strain sequencing for the study, “vaccine efficacy against specific SARS-CoV-2 variants cannot be evaluated at this time,” the FDA staff wrote. 

Besides staving off COVID-19 infection altogether, the vaccine was 85% effective at preventing severe COVID-19 infection and kept people out of the hospital at least 28 days after vaccination.

The most common side effects were pain at the injection site, affecting about half of the patients, and headache and fatigue, both striking about 38% of the patients. Side effects were generally mild to moderate with 1% to 2% reported as severe.

Seven patients in the vaccine group suffered serious side effects, three of which the FDA staff linked to the vaccine. One had a hypersensitivity reaction to the shot featuring hives, muscle and joint pain, fatigue, and an itchy, tight throat, but did not meet the criteria for anaphylaxis. Another patient had severe and persistent pain at the injection site, and a third had what the FDA called severe systemic reactogenicity, namely severe side effects felt throughout the body, including fever, shortness of breath, chest pain and numbness and tingling in the upper extremities.

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The studies turned up a few effects that hit more people in the vaccine group than in the placebo group, such as hives and tinnitus. However, they affected only a tiny fraction of the overall population, with many of the patients suffering them “having predisposing risk factors.” In all, the FDA staff deemed the data insufficient to link these effects to the vaccine.

As of the Jan. 22 data cutoff, there were 19 deaths in the study: 16 in the placebo group and three in the vaccine group. Between Jan. 22 and Feb. 5, six more patients died. Two patients in the vaccine group died of “respiratory infections not due to COVID-19.” Of the seven patients who died of COVID-19 infection, all were in the placebo group and all were in study sites in South Africa.

The study participants were 62.1% white, 17.2% Black or African American, 3.5% Asian, 8.3% American Indian or Alaska Native and 0.3% Native Hawaiian or other Pacific Islander. Nearly half of the participants were Hispanic or Latino.

A panel of outside experts will convene on Friday to discuss the vaccine’s data and vote whether to recommend it for emergency authorization. It follows similar panels for Pfizer and Moderna’s COVID-19 vaccines, which scored emergency nods within days of the panel discussions.