The pharmaceutical giant has conducted one of the biggest vaccine trials in the world.
One of the biggest vaccine trials in the world says its vaccine is 90% effective.
US pharmaceutical giant Pfizer said the first interim results from its large-scale trials found the vaccine to be effective for nine out of ten people who had not been infected before.
It is a far higher efficacy rate than many experts had hoped for. Regulators were prepared to accept a vaccine that was just 50% effective.
The company said today is a "great day for science and humanity", with tests showing no evidence of side effects.
