COVID-19 Resource Center

COVID-19 Resource Center

Source: Press Release
Disclosures: Fauci and Offit report no relevant financial disclosures.
January 29, 2021
2 min read

One-shot J&J vaccine 85% effective against severe disease, 66% effective overall

Source: Press Release
Disclosures: Fauci and Offit report no relevant financial disclosures.
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Johnson & Johnson said its one-shot COVID-19 vaccine candidate was 85% efficacious at preventing severe disease in a phase 3 trial being conducted in eight countries, and 66% efficacious overall at preventing moderate to severe disease.

In a press release, the company reported that the vaccine’s efficacy was 72% in the United States, 66% in Latin America and 57% in South Africa, where 95% of COVID-19 cases that occurred during the trial were from the SARS-CoV-2 variant, B.1.351, that has raised concerns over its ability to evade vaccines or treatments. The variant was reported in the U.S. for the first time this week.

COVID-19 sign
The Johnson & Johnson vaccine is given in one dose.
Credit: Adobe Stock

Efficacy data from the ENSEMBLE trial, which enrolled more than 43,000 adults, are from 28 days after vaccination. Johnson & Johnson said the onset of protection was observed as soon as 14 days, and that the vaccine’s efficacy against severe disease “increased over time, with no cases in vaccinated participants reported after day 49.”

In September, when the phase 3 trial began, National Institute of Allergy and Infectious Diseases Director Anthony S. Fauci, MD, said the vaccine “may be especially useful in controlling the pandemic if shown to be protective after a single dose.”

The two COVID-19 vaccines currently authorized for use in the U.S. are both given in two doses, either 21 or 28 days apart. Those vaccines, manufactured by Pfizer-BioNTech and Moderna, were developed using messenger RNA technology. The U.S. has ordered hundreds of millions of doses of each.

Anthony S. Fauci
Paul A. Offit

The Johnson & Johnson shot is a recombinant vector vaccine that uses a human adenovirus that has been modified to no longer replicate in humans and cause disease.

Pfizer and Moderna have said their vaccines, which both demonstrated high efficacy in phase 3 trials. appeared to be protective in lab experiments against emerging SARS-CoV-2 variants first reported in South Africa and the United Kingdom.

A protein-based vaccine being developed by Novavax demonstrated close to 90% efficacy in the U.K. but was around 49% effective in a trial in South Africa, where almost all of the cases were due to the variant, the company announced yesterday.

Paul A. Offit, MD, director of the Vaccine Education Center at Children's Hospital of Philadelphia, called the Johnson & Johnson data “encouraging.”

“Even in South Africa, it was roughly 89% protective against severe disease. That's good,” Offit told Healio. “Obviously the South African strain is not as sensitive to these vaccines … as the U.K. strain or the strain that first came out of Wuhan. But still, the mRNA vaccine set a high goal for protection against the virus that is most common in the United States. But we knew the South African strain was going to be somewhat less susceptible to vaccine induced immunity, but if it's still relatively highly susceptible to vaccine induced immunity regarding severe disease, I think that's good.”

Fauci has said that an FDA emergency use authorization for the Johnson & Johnson vaccine could come as early as February. The vaccinee can be kept for 2 years at –4°F, including at least 3 months normal refrigeration temperature of 36°F to 46°F, unlike some of the other vaccines, which require extremely cold storage.