Study: Mixing COVID-19 vaccine doses increases mild symptoms, no other safety concerns by The Canadian Press Last Updated May 13, 2021 at 10:18 am EDT Dr. Joss Reimer, medical lead, Manitoba Vaccine Implementation Task Force draws a dose of the AstraZeneca COVID-19 vaccine at a clinic in Winnipeg, Friday, March 19, 2021. THE CANADIAN PRESS/John Woods Preliminary results of an ongoing study in the United Kingdom suggest alternating the Oxford-AstraZeneca and Pfizer-BioNTech vaccines causes more frequent mild to moderate symptoms, but there are no other safety concerns from mixing those vaccine...