Johnson & Johnson’s one-time Covid-19 vaccine was found to be 66% effective in preventing moderate and severe diseases in a global phase 3 study, but 85% effective against serious diseases, the company announced Friday.
The vaccine was 72% effective against moderate and severe disease in the US, the company said.
It’s a striking difference from Pfizer / BioNTech and Moderna vaccines, and it can shut down people who aren’t sure which vaccine to get or when they can get one. The vaccines already on the market in the US are about 95% effective against symptomatic Covid-19 in total, with perhaps even greater efficacy against severe cases.
Experts say the Johnson & Johnson vaccine, developed by its Janssen vaccine division, will still be useful against the pandemic in the United States and around the world, even if the single-dose vaccine does not become the first choice for many .
For Johnson & Johnson, efficacy against moderate and severe varied from country to country: 72% in the US, 66% in Latin America, and 57% in South Africa. This was measured from one month after admission.
In South Africa, 95% of the cases in the study were due to a variant known as B.1.351, which is known to be more contagious and carries mutations that may make the virus less susceptible to the immune response of the antibody – including antibodies caused by vaccination.
With that variant, “we have lower protection against milder forms of Covid than in the United States, where there were more typical circulating variants,” said Dr. Mathai Mammen, the company’s global head of research and development, to CNN’s Chief Medical Correspondent, Dr. Sanjay Gupta.
Even those who got moderate cases of Covid-19 during the study tended to develop a milder course and fewer symptoms, he added.
But for Mammen, the main outcome was how effective the vaccine was in preventing serious illness – regardless of variant or age group.
“In all regions, in all variants, we see 85% protection” against serious diseases, he said. That trend increased over time, with no serious cases in the vaccinated group after Day 49, the company said.
From one month after the injection, all hospitalizations and deaths occurred in the placebo group.
The results are based on an analysis of more than 44,000 participants in eight countries, with a total of 468 cases of Covid-19 distributed among those who received the vaccine or placebo. The results have not been published in a peer-reviewed journal, but the company said it plans to do so “in the coming weeks.”
Johnson & Johnson is expected to file next week with the U.S. Food and Drug Administration for emergency use authorization, which Mammen said could come in late February.