The first coronavirus vaccine can prevent more than 90% of people from getting Covid-19 according to preliminary analysis.
The developers – Pfizer and BioNTech – described it as a “great day for science and humanity”.
Their vaccine has been tested on 43,500 people in six countries and no safety concerns have been raised.
The companies plan to apply for emergency approval to use the vaccine by the end of the month.
There are around a dozen vaccines that have reached the final stages of testing, but this is the first to show any results.
It uses a completely experimental approach – that involves injecting part of the virus’s genetic code – in order to train the immune system.
Two doses are needed, three weeks apart, and the pharmaceutical companies say people are protected a week after the second dose.
It has been trialled in the US, Germany, Brazil, Argentina, South Africa and Turkey.
Pfizer believes it will be able to supply 50 million doses by the end of this year and around 1.3 billion by the end of 2021.