British scientists are starting a 13-month vaccine trial to test whether COVID-19 vaccines can be mixed and matched.
The vaccines that are rolling out now require two doses, weeks apart, and experts have been recommending they should be the same kind.
In the new study, participants will get one shot of the AstraZeneca vaccine followed by a Pfizer dose, or vice versa.
The vaccines use different technologies and it’s unclear whether mixing them might work. But British officials say that, if successful, the study could allow for more flexible policies and help deal with vaccine shortages.
Researchers will also be looking at the length of time between the doses. Determining if vaccination is more effective with a four-week or 12-week gap between them.
"If we do show that these vaccines can be used interchangeably in the same schedule this will greatly increase the flexibility of vaccine delivery, and could provide clues as to how to increase the breadth of protection against new virus strains," said Oxford University's Matthew Snape, chief investigator of the National Immunisation Schedule Evaluation Consortium, leading the trial.
Researchers are hoping to enroll 800 volunteers, and say they could have initial results of antibody levels by mid-summer.
