Manufacturing moonshot: How Pfizer makes its millions of Covid-19 vaccine doses

When the coronavirus pandemic began, the challenge for Pfizer and BioNTech wasn't just developing its Covid-19 vaccine -- it also had to make it, and by the hundreds of millions.

This was no small feat. Until the very end of last year, no mRNA vaccine had ever been authorized and no such vaccine had ever been manufactured to scale by any company.