Covid vaccine: 'That was a huge calculated risk'

The Serum Institute of India (SII) isn't a household name, but it's the world's largest vaccine maker.

It is currently making Covid vaccines under license for pharmaceutical firms such as AstraZeneca.

"The most important part that enabled us to have so many doses - 70-80 million in January - was because I started manufacturing at risk in August," Serum Institute of India's chief executive Adar Poonawalla tells the BBC.

"That was a huge calculated risk - it wasn't a blind risk, because we knew the Oxford scientists from our earlier collaboration with the malaria vaccine that we're making with them."