A new study suggests that mixing doses of the AstraZeneca and Pfizer vaccines generates a stronger immune response against COVID-19 than having two rounds of AstraZeneca. 

The findings, published online by Lancet on Monday, come from the University of Oxford-led Com-COV study.

The study explored the use of different combinations of approved COVID-19 vaccines: two doses of Pfizer, two of AstraZeneca, and mixing doses of AstraZeneca and Pfizer.

The study demonstrated that the mixed doses produced more antibodies than the standard two-dose AstraZeneca schedule, but the two-dose Pfizer regimen generated the highest antibody response overall.

The trial results hint that people who have already received two doses of the AstraZeneca vaccine could have a stronger immune response if they were given a different vaccine as a booster.