The Com-Cov study is investigating whether giving a first dose of one vaccine followed by a second dose of another vaccine prompts an immune response as strong as if two doses of the same vaccine were administered.
Matthew Snape, associate professor in paediatrics and vaccinology at the University of Oxford and chief investigator on the trial, said: “The focus of both this and the original Com-Cov study is to explore whether the multiple COVID-19 vaccines that are available can be used more flexibly, with different vaccines being used for the first and second dose.
“If we can show that these mixed schedules generate an immune response that is as good as the standard schedules, and without a significant increase in the vaccine reactions, this will potentially allow more people to complete their COVID-19 immunisation course more rapidly.
“This would also create resilience within the system in the event of a shortfall in availability of any of the vaccines in use.”