Pfizer's coronavirus vaccine candidate is 'viable' — but there are some side effects

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The first clinical data on the vaccine candidate produced by pharmaceutical giant Pfizer in partnership with German biotech firm BioNTech showed some positive results, although there were side effects, Stat News reports.

The study randomly assigned 45 patients one of three doses of the vaccine — which relies on experimental messenger-RNA technology — or a placebo. The bad news is half of the patients who received the highest dose of the vaccine developed fevers, so they weren't given a second injection, but those who received the two lower doses did receive a second dose. After the follow-up shot, more than 50 percent of the volunteers reported some kind of adverse effect, including fevers and sleep disturbances. That's troublesome, but none of the side effects were considered life-threatening or resulted in hospitalization or disability.

Now, for the good news. The vaccine generated neutralizing antibodies that prevent the coronavirus from functioning, and the levels of those neutralizing antibodies were 1.8 to 2.8-times the levels found in recovered COVID-19 patients.

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No one knows if antibodies lead to immunity, and Pfizer, like every manufacturer with a potential vaccine candidate, will have to conduct larger studies to figure that out. Despite the uncertainty and the side effects, the initial findings represent a promising first step. "We still have a ways to go and we're testing other candidates, as well," said Philip Dormitzer, the chief scientific officer for viral vaccines at Pfizer. "However, what we can say at this point is there is a viable vaccine candidate based on immunogenicity and early tolerability safety data." Read more at Stat News.

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Tim O'Donnell

Tim is a staff writer at The Week and has contributed to Bedford and Bowery and The New York Transatlantic. He is a graduate of Occidental College and NYU's journalism school. Tim enjoys writing about baseball, Europe, and extinct megafauna. He lives in New York City.