May 13, 2021
By Jane Brown
We’re learning from British researchers what side effects there might be when people mix COVID-19 vaccine doses for their first and second shots.
Preliminary results suggest combining two different shots causes more frequent mild to moderate symptoms, but no other safety concerns.
Specifically, the scientists say an increase in short term adverse reactions occurred after the AstraZeneca vaccine was followed four weeks later by the Pfizer vaccine, or vice versa.
Dr. Peter Juni is scientific director of Ontario’s Science Table.
He told Zoomer Radio’s Fight Back with Libby Znaimer, this information on symptoms and side effects precedes research on how the combination of vaccines affects immunity against COVID-19.
Listen for Libby’s full conversation with Dr. Juni by clicking here.
Researchers also noted that while the study participants are 50 and older, it is possible that adverse reactions may be more prevalent in younger people, though they did not provide any details on this.
The study recruited 830 people to evaluate four combinations of vaccination: a first dose of AstraZeneca followed by a second shot of the Pfizer vaccine or another dose of AstraZeneca, or the Pfizer vaccine followed by a second shot of either AstraZeneca or Pfizer.