Covid-19: why mix and match vaccines?

The Com-Cov trial run by the Oxford Vaccine Group in the UK will be testing the efficacy and safety of a ‘mix and match’ approach to immunisation. By giving some participants either the Pfizer/BioNTech or Oxford/AstraZeneca vaccine, and a second dose of the other, the trial aims to find out if combining different jabs offers sufficient protection. Sarah Boseley speaks to Dr Peter English about where this technique has been used in the past, why it could be beneficial, and how mixing vaccines actually works. Help support our independent journalism at theguardian.com/sciencepod