Is the Covid vaccine safe?
The UK's Covid immunisation programme is set for a massive expansion following the approval of the Oxford-AstraZeneca vaccine.
More than 600,000 people in the UK have been vaccinated against coronavirus so far using the already approved Pfizer-BioNTech jab. While many people want an injection as soon as possible, others are worried about putting something unknown into their bodies.
How do we know a vaccine is safe?
Safety trials begin in the lab, with tests and research on cells and animals, before moving on to human studies.
The principle is to start small and only move to the next stage of testing if there are no outstanding safety concerns.
How will I get a coronavirus vaccine?
Who will get the vaccine first and when can you have it?
Your Questions Answered: How do we know the vaccine is safe?
What role do trials have?
As long as the safety data from the labs is good, scientists can check that the vaccine or treatment is effective too.
That means tests on large numbers of volunteers - around 40,000 individuals in the case of Pfizer-BioNTech - which was the first vaccine to be approved in the UK.