Early results from the world's first effective coronavirus vaccine showed it could prevent more than 90% of people from getting Covid-19.
The vaccine had been developed by pharmaceutical companies Pfizer and BioNTech and was one of 11 vaccines that had reached the final stages of testing.
Mark Coles explores the lives and careers of Ugur Sahin and Ozlem Tureci - the little known Turkish-German husband-and-wife team responsible for the development of the vaccine.
First broadcast on Saturday 14th November 2020.
Producers: Sally Abrahams and Ben Carter Editor: Rosamund Jones