Research Scientists Mix-Match Vaccines to Study Compatibility
Scientists in the U.K. are trying to determine what happens when different types of vaccines are mixed up on purpose.
More than 800 volunteers over the age of 50 are taking part in the study.
They were given either one Pfizer shot, one AstraZeneca shot, or the same vaccine twice for comparison.
Shots are given between four and 12 week gaps to see what works best.
Scientists hope it will help with shortages and protect against new variants.