New Phase 3 Trial Data Suggest Johnson & Johnson’s COVID-19 Vaccine Could Be Efficacious Against Newly Emerging Variants

Recent data from a phase 3 clinical trial reveal that Johnson & Johnson’s COVID-19 vaccine, which was submitted to the U.S. Food and Drug Administration for emergency use authorization on February 4, is 66% efficacious at preventing COVID-19 disease. That finding, together with other properties of the single-dose vaccine, suggest it could be a “tremendous tool in the fight against this pandemic,” says Hanneke Schuitemaker, PhD, a lead scientist at Janssen, which is the pharmaceutical company of Johnson & Johnson.

Although the 66% efficacy level falls below that of other vaccine frontrunners, scientists found the vaccine to be 85% efficacious at preventing severe COVID-19 disease by 28 days after vaccination. Additionally, the candidate appears to prevent severe disease in people infected with new, potentially more contagious strains, Schuitemaker said during The Quest for a Covid-19 Vaccine, a symposium hosted by the New York Academy of Sciences.

These findings, which were released on January 29, are based on Johnson & Johnson’s phase 3 trial called ENSEMBLE. It included nearly 44,000 participants age 18 and older in the United States, South Africa, and in countries across Central and South America. In the United States, the vaccine was found to be 72% efficacious at preventing COVID-19 disease.

Schuitemaker explained that the team analyzed samples collected from the 468 participants who developed COVID-19 disease during the trial. They found that 97% of infections in South Africa were due to the B.1.351 variant, which was first identified in that country and may be more contagious than the original SARS-CoV-2 strain. Although the Johnson & Johnson vaccine was less efficacious at preventing disease from this variant, “the good news” is that scientists did not see a drop in the vaccine’s ability to prevent severe disease and hospitalization from B.1.351. In Brazil, they did not detect B.1.351 because the trial sites were not in regions where this variant is prevalent. However, there were infections with variants in the P.1 lineage, first seen in Brazil, and the vaccine did not lose efficacy at preventing disease caused by these variants.

“We are happy with this outcome,” Schuitemaker said at the symposium. Prior to launching the ENSEMBLE trial, the company aimed for an efficacy of 70%. Although results missed the mark somewhat, Schuitemaker thinks the vaccine will still play an important role in halting the pandemic because of its efficacy at preventing severe disease and disease caused by newly emerging variants, as well as its stability at refrigerator temperatures for up to 3 months. Johnson & Johnson is currently conducting a second phase 3 trial, called ENSEMBLE 2, in European and Asian countries that gives two doses of the vaccine, which is based on a non-replicating adenovirus that expresses the SARS-CoV-2 spike protein.

Johnson & Johnson aims to provide 1 billion doses of the vaccine this year, Schuitemaker says. She adds, “only if we make [vaccines] available around the world, can we stop [this pandemic].”