A UK trial is being launched on the mixing of covid-19 vaccines for first and second doses.
Scientists want to see if receiving different vaccines could boost protection for people, and also add flexibility to rollouts.
The study will start by mixing Pfizer and AstraZeneca jabs and may add other vaccines as they are approved by regulators.
Vaccines Minister Nadhim Zahawi says it doesn't affect the immediate rollout of the vaccination programme.
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