The UK has ordered almost 370 million doses of seven coronavirus vaccines in the biggest and most expensive immunisation programme in history.
Two of those vaccines - one by Pfizer/BioNTech and the other by Oxford University/AstraZeneca - have already been injected into the arms of millions of Britons.
A third, developed by Moderna, has been approved by the UK's medicines regulator and is due to be distributed in the spring.
The other four vaccines that have been ordered in the millions were developed by Novavax, Janssen, Valneva and GlaxoSmithKline/Sanofi Pasteur, and are at various stages of ongoing trials.