Mixing brands of COVID-19 vaccines can create strong protection against COVID-19, early results of a British study suggest, The New York Times reported June 28.
In a clinical trial that began in February, volunteers showed high levels of antibodies and immune cells after getting one dose of Pfizer's COVID-19 vaccine and one dose of AstraZeneca's.
In the first part of the trial, researchers gave 830 volunteers one of four combinations of the vaccines: two doses of either Pfizer or AstraZeneca's vaccine, one Pfizer vaccine followed by one AstraZeneca vaccine, or vice versa. Researchers waited four weeks between doses, according to the Times.
The people who received two doses of Pfzier's vaccine had levels of antibodies roughly 10 times as high as those who got AstraZeneca's. Those who got a shot of Pfizer's vaccine followed by a shot of AstraZeneca's vaccine had antibody levels roughly five times as high as those with two doses of AstraZeneca. And those who received a shot of AstraZeneca's vaccine followed by Pfizer's vaccine had antibody levels roughly as high as those who got two doses of Pfizer, the Times reported.
The study, published in The Lancet, also found that using two different vaccine brands produced a higher level of immune cells ready to attack the coronavirus than two of the same shots did, the Times reported. It's unclear why it had that effect.
Volunteers who got one dose of each shot reported more chills, headaches and muscle pain following vaccination than those who got two doses of the same shot, but the side effects were short lived, researchers said.
The researchers are also running a separate trial with 12 weeks in between doses. Similar trials have begun adding in vaccines from Moderna and Novavax as well, the Times reported.
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