British researchers set out to find whether mixing vaccines is an effective way to protect individuals against COVID-19, but they found that taking one dose of Pfizer and then a second dose of Moderna nine weeks later actually produced a better immune system response than just the two doses of Pfizer.
The study, which was conducted by researchers at Oxford University, examined the immune system responses of 1,070 subjects who took some combination of the Oxford-AstraZeneca, Pfizer-BioNTech, Novavax, and Moderna vaccines.
Individuals who took AstraZeneca followed by Moderna or Novavax also produced higher antibodies and T-cell responses than those who took two doses of AstraZeneca.
A dose of Pfizer followed by Novavax produced better results than two doses of AstraZeneca, but a lower immune system response than two doses of Pfizer.
“Encouragingly, all these schedules generated antibody concentrations above that of the licensed and effective two dose Oxford-AstraZeneca schedule,” Professor Matthew Snape, Associate Professor in Vaccinology at Oxford and chief investigator on the trial, said Monday.
“When it comes to cellular immunity, having a first dose of the Oxford-AstraZeneca vaccine followed by any of the other study vaccines generates a particularly robust response.”
Under current CDC recommendations, Americans can mix and match vaccines when getting their booster shots.
European Union health officials endorsed mixing and matching on Tuesday, saying that mixing may “induce an expanded breadth of immune responses.”
Mixing vaccines could be a vital tool in poorer countries that have struggled with the availability of vaccines.
Only 6.3% of people in low-income countries have received at least one dose, according to Oxford University’s Our World in Data project.