A news article in Nature describes a study led by the Carlos III Health Institute in Madrid that explored the benefits of combining different coronavirus vaccines. Preliminary results show that vaccinating people with both the Oxford–AstraZeneca and Pfizer/BioNTech COVID-19 vaccines produces a potent immune response against the virus SARS-CoV-2. The trial of more than 600 people — announced in an online presentation on 18 May — is the first to show the benefits of combining different coronavirus vaccines.
Because of safety concerns, several European countries are already recommending that some or all people who were given a first dose of the Oxford–AstraZeneca vaccine get another vaccine for their second dose. Researchers hope that such mix-and-match COVID-19 vaccination regimens will trigger stronger, more robust immune responses than will two doses of a single vaccine, while simplifying immunization efforts for countries facing fluctuating supplies of the various vaccines.