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Another COVID-19 vaccine may be available to Americans as soon as next month. The vaccine is made by Janssen Pharmaceuticals Company, a division of Johnson & Johnson. Today, the company published interim data showing that the vaccine appears to be safe and that it elicits the kind of immune response that should protect someone from COVID. As NPR's Joe Palca reports, evidence that the vaccine actually does prevent illness is expected later this month.
JOE PALCA, BYLINE: The preliminary results come from two studies of about 400 participants each. One involved people aged 18 to 55, the other, older than 65. Some subjects got a single dose of the vaccine. Some got two. Some got a high dose, some a low dose. Although the participants were roughly evenly split between men and women, nearly all the participants were white.
As they report in the New England Journal of Medicine, researchers found that most adverse reactions to the vaccine were mild and dissipated within 24 hours. One participant had a high fever, but it only lasted 12 hours. Younger subjects tended to have more negative reactions to the vaccine than older ones. Laboratory results showed that most subjects had the kind of immune response that should protect them from disease 29 days after the first shot, and virtually all showed that response after 57 days.
But these are just laboratory studies. Moncef Slaoui, with the government's Operation Warp Speed, said in a press teleconference yesterday that the results from a study involving 45,000 volunteers will be needed to show whether the vaccine actually protects people from disease. That study completed enrollment in mid-December.
MONCEF SLAOUI: We are very clear that analysis will be completed before the end of the month.
PALCA: The month of January. Slaoui said if that analysis shows the vaccine is working as hoped, the Food and Drug Administration could issue an emergency use authorization for the vaccine as soon as February. In its initial projections, Janssen planned to have 12 million doses by the end of February, but Slaoui said, based on the latest estimates, he was only expecting doses numbering in the single digit of millions.
SLAOUI: We're trying to make that number get as close to a double-digit number as possible, and then a larger number in March and a much larger number in April.
PALCA: The good news is the Janssen vaccine should be rolled out as a single-dose vaccine, so people won't need to go back for a booster shot as they do with the Moderna and Pfizer-BioNTech vaccines. Joe Palca, NPR News. Transcript provided by NPR, Copyright NPR.