Others got a dose of AstraZeneca followed by one of Pfizer, or vice versa. Those who got two doses of Pfizer-BioNTech produced levels of antibodies about 10 times greater than in those who got two doses of AstraZeneca. Volunteers who got Pfizer-BioNTech followed by AstraZeneca produced antibody levels about five times greater than in those who received two doses of AstraZeneca. And volunteers who got AstraZeneca followed by Pfizer-BioNTech reached antibody levels about as great as in those who got two doses of Pfizer-BioNTech. Mixing the vaccines produced higher levels of the cells than two doses of the same vaccine.

Source: New York Times June 28, 2021 22:14 UTC