Mixing Covid-19 vaccines trial expands to include two additional jabs Sign up for our daily newsletter of the top stories in Courier country Thank you for signing up to The Courier daily newsletter Something went wrong - please try again later. Sign Up A study looking at whether the Oxford/Astrazeneca and Pfizer coronavirus vaccines can be safely mixed for the first and second doses will be expanded to include two additional jabs. Researchers running the Com-Cov study, launched in February to investigate alternating doses of the first two jabs to be rolled out across the UK, have announced the programme will be extended to include the Moderna and Novavax vaccines.