One simple chart shows how well J&J's single-dose coronavirus vaccine works, with protection starting after 2 weeks

johnson and johnson covid vaccine
Johnson & Johnson's coronavirus vaccine is delivered as a single shot, while both Pfizer and Moderna's require two jabs. Thiago Prudêncio/SOPA Images/LightRocket via Getty Images
  • A third US-authorized coronavirus vaccine is closer than ever.

  • Johnson & Johnson's single-dose shot was safe and effective at preventing COVID-19, US regulators said.

  • One chart from the FDA's review shows how well the vaccine works, with protection coming after two weeks.

  • Visit the Business section of Insider for more stories.

Johnson & Johnson's coronavirus vaccine starts protecting people from getting sick with COVID-19 about two weeks after immunization.

The Food and Drug Administration released a 62-page review of the vaccine on Wednesday. The documents shows that the shot is safe and effective against COVID-19. The one-dose vaccine is in the final stages of the US review process for emergency authorization, which could come as early as this weekend or early next week.

One simple chart in the FDA's review shows a key takeaway from J&J's study: its one-dose vaccine works quite well, leading to far fewer COVID-19 cases among volunteers who received the shot. J&J's vaccine was 67% effective after two weeks and 66% effective after four weeks from injection, according to the FDA's review documents.

The red line represents the total number of COVID-19 cases in the control group, or people who got the bogus placebo shot. The blue line shows the number of cases among people who received the real J&J shot. The two groups diverge right around 14 days, with far more COVID-19 cases being tallied in the placebo group from that point.

Effectiveness of Johnson & Johnson's coronavirus vaccine compared to placebo
Effectiveness of Johnson & Johnson's coronavirus vaccine compared to placebo FDA

J&J's efficacy figures are markedly lower than the 94% and 95% efficacy rates shown by two-dose vaccines from Moderna and Pfizer , but it's difficult to directly compare the studies, as they happened at different stages in the pandemic and across different geographies.

Expect a debate among experts in the coming days over just how much the efficacy difference matters.

Still, J&J's shot works quite well, especially at preventing the worst outcomes of disease. Across the entire study, 31 people wound up in the hospital from COVID-19: 29 had received the placebo shot and just two had gotten J&J's vaccine. The study also tallied seven deaths from COVID-19, all in the placebo group.

Experts have argued the key benefit of COVID-19 vaccines is being able to prevent people from needing hospitalization or dying. J&J's shot clears that bar, and the company has been highlighting its unique advantages in being a one-dose shot that can be stored at typical refrigerator temperatures for three months.

An FDA advisory committee will meet Friday to discuss J&J's shot and ultimately vote on whether or not to recommend emergency authorization. If OK'd by regulators, the healthcare giant has said it will be able to ship 4 million doses immediately and that it's on track to deliver 100 million doses to the US by the end of June.

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