The vaccine trains the immune system to fight coronavirus.
It is a new type of jab called an RNA vaccine and uses a tiny fragment of the virus’s genetic code. This starts making part of the virus inside the body, which the immune system recognises as foreign and starts to attack.
The genetic material is encased in a tiny protective bubble of fat to get it into cells.
The exact ingredients of the vaccine have not been made public, but other vaccines can contain other ingredients, like aluminium, to make them stable or more effective.
The vaccine is given in two doses – three weeks apart – and offers up to 95% protection against Covid-19.