Johnson & Johnson’s single-dose vaccine offers strong protection against severe COVID-19, according to new documents and analysis released by US regulators.
The highly anticipated vaccine, that could speed vaccinations by requiring just one dose, was confirmed to be 66% effective at preventing moderate to severe COVID-19 and about 85% effective against the most serious illness.
US Food and Drug Administration (FDA) regulators are set to meet on Friday to decide whether to recommend the vaccine be authorised. A final decision is expected within days.
Johnson & Johnson tested its single-dose option in 44,000 adults in the US, Latin America and South Africa.
The FDA documents said efficacy in South Africa was around 64%, slightly above the 57% the company announced previously. The vaccine was found to be more effective in the US at 72% a month after the single dose was given. It was 61% effective in Latin America.
The vaccine was 85% effective in the US against severe disease and 81% effective against severe disease in South Africa. It was 87% effective against severe and critical disease in Brazil.
But as different variants circulate globally, the FDA scientists warned that it's not clear how well it will work against each new variant.
South Africa recently began giving the J&J vaccine to front-line health workers on a test basis after deciding to stop rollout of the AstraZeneca vaccine that did not show strong study results against the more transmissible variant spreading there.
Johnson & Johnson is testing to see if a second dose of the vaccine works better, which could become a booster shot further down the line.
The main side effects were fatigue, fever, pain at the injection site and headache. No study participant experienced a severe allergic reaction, called anaphylaxis, that is a rare risk of some other COVID-19 shots, although one experienced a less serious reaction.
European regulators plan to give an opinion on the vaccine over the coming weeks.