Johnson & Johnson’s Covid-19 single dose vaccine was shown to be 66% effective in preventing moderate and severe illnesses in a global Phase 3 trial, but 85% effective against serious illnesses, the company announced on Friday.
The vaccine was 72% effective against moderate and severe illnesses in the United States, the company said.
It is a marked difference from Pfizer / BioNTech and Moderna vaccines, and can make people hesitate about which vaccine to get or when to get it. Vaccines already available on the market in the United States are about 95% effective in general against symptomatic Covid-19, perhaps even more effectively against severe cases.
Experts say the Johnson & Johnson vaccine, developed by his Janssen vaccine arm, 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, the effectiveness against moderate and severe varied from country to country: 72% in the USA, 66% in Latin America and 57% in South Africa. This was measured from one month after the injection.
In South Africa, 95% of the cases in the trial were due to a variant known as B.1.351, which is known to be more contagious and carries mutations that can make the virus less susceptible to the immune antibody response – including antibodies caused by vaccination .
With this variant, “we have less protection against the milder forms of Covid than we had in the United States, where there were more typical variants in circulation,” said Dr. Mathai Mammen, the company’s global head of research and development, to the chief CNN Correspondent physician, Dr. Sanjay Gupta.
Even those who had moderate cases of Covid-19 on the test tended to develop a smoother course and less symptoms, he added.
But for moms, the main result was the vaccine’s effectiveness in preventing serious illnesses – regardless of variant or age group.
“In all geographies, in all variants, we see 85% protection” against serious illness, he said. This trend has increased over time, with no serious cases in the vaccinated group after the 49th day, according to the company.
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 468 total cases of Covid-19 divided between those who received the vaccine or placebo. The results were not published in a peer-reviewed newspaper, but the company said it plans to do so “in the coming weeks”.
Johnson & Johnson is expected to apply to the US Food and Drug Administration next week for emergency use authorization, which Mammen said could arrive in late February.