The COVID-19 vaccine jointly developed by AstraZeneca and the University of Oxford may reduce transmission of the novel coronavirus by two-thirds, according to early research published Feb. 2 in The Lancet's preprint section.
The interim analysis was based on phase 3 clinical trials conducted in the U.K., Brazil and South Africa in which 17,177 participants accrued 332 symptomatic cases of COVID-19.
University of Oxford researchers found a 67 percent reduction in positive swabs among trial participants who received at least one vaccine dose. The interim analysis marks the first time data has suggested a COVID-19 vaccine can reduce virus transmission.
Researchers also found that a single dose of the vaccine was 76 percent effective at preventing COVID-19 over a three-month period. The vaccine was 82 percent effective in trial participants who received a second dose three months after their first.
"This primary analysis reconfirms that our vaccine prevents severe disease and keeps people out of hospital," Sir Mene Pangalos, PhD, AstraZeneca's executive vice president of biopharmaceuticals and research and development, said in a news release. "In addition, extending the dosing interval not only boosts the vaccine’s efficacy, but also enables more people to be vaccinated upfront. Together with the new findings on reduced transmission, we believe this vaccine will have a real impact on the pandemic."
Some health experts have expressed skepticism about AstraZeneca's announcement, saying more evidence is needed to back up the drugmaker's claims.
“While this would be extremely welcome news, we do need more data before this can be confirmed and so it’s important that we all still continue to follow social distancing guidance after we have been vaccinated,” Doug Brown, PhD, the British Society for Immunology's CEO, told The New York Times.
Editor's note: This article was updated at 10:20 a.m. CST to include more context.
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