Johnson & Johnson's coronavirus vaccine is delivered as a single shot, while both Pfizer and Moderna's require two jabs.
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  • A panel of independent experts voted unanimously Friday in favour of recommending Johnson & Johnson's coronavirus vaccine. 
  • US regulators are expected to authorise the single-dose vaccine in the coming days. 
  • J&J has said it will be able to ship nearly 4 million doses following a regulatory OK. 
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Johnson & Johnson's experimental coronavirus vaccine just passed a critical hurdle, as a group of top doctors and scientists voted unanimously to endorse the shot.

The US Food and Drug Administration is now expected to authorise the vaccine to be given widely in the coming days. The FDA typically follows the panel's advice, but isn't required to do so. An emergency use authorization (EUA) would likely allow the shot to be given widely to people 18 and older. 

FDA regulators released their own summary of J&J's data on Wednesday, finding the shot to be safe and effective

The vaccine has a 64% efficacy rate at preventing the more contagious South African variant, according to the report posted online by the FDA.

The new report found its efficacy rate against the 501Y.V2 variant is seven percentage points higher than an earlier report released by the company. Johnson & Johnson previously said that the vaccine offers 57% protection against moderate to severe Covid-19 infections in South Africa.

See also: J&J vaccine works better against SA variant than previously reported

Vaccine efficacy against severe Covid cases was 73%, 14 days after vaccination, increasing to 82% at least 28 days after vaccination.

There were no deaths due to Covid among South African trial participants who received the J&J vaccine. More than 5,000 South Africans took part in the J&J vaccine trial, of which around half received a placebo vaccine.

"These results suggest that the vaccine is efficacious against mortality associated with Covid-19," the report found.

The healthcare giant ran a study with about 40,000 volunteers, comparing its vaccine to a placebo. That trial found the shot was 66% effective at preventing moderate-to-severe Covid-19. The first two US-authorized vaccines demonstrated 94% and 95% efficacy at preventing symptomatic cases of Covid-19, though experts cautioned against comparing those figures directly.

A key challenge for J&J's shot will be explaining to the general public how it compares to the other vaccines, committee members said.

"We have a vaccine now that has good efficacy that everyone is going to compare to the existing vaccines and say it doesn't look quite as good," said panelist Dr. Eric Rubin, an infectious-disease expert and editor-in-chief of The New England Journal of Medicine. 

J&J has emphasised its vaccine's ability to prevent the worst outcomes of Covid-19

J&J has said it will have nearly 4 million doses ready to ship upon emergency authorisation and is on track to deliver 100 million doses to the US by the end of June. Beyond the much-needed supply bump, public-health experts are eager to roll out the vaccine for its simplicity: it's a single-dose vaccination that can be stored at typical refrigerator temperatures for several months.

More than 47 million Americans, or nearly 1 in 5 adults in the US, have received at least one dose of a coronavirus vaccine, according to the Centers for Disease Control and Prevention.  

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