Did Covid vaccines really save 12 million lives?

The BBC reported that AstraZeneca and Pfizer are credited with together saving more than 12 million lives in the first year of Covid vaccination. To substantiate this claim, the BBC refers to Airfinity, a ‘disease forecasting company’.

Airfinity used an Imperial College London study, which calculated that Covid vaccines saved 20 million lives between December 2020 and December 2021. Using a mathematical model, the Imperial team assumed that vaccination conferred protection against Covid infection (mRNA vaccines were estimated to have given 88 per cent protection against infection after the second dose) and the development of severe disease requiring hospital admission. The team also assumed that those who develop infection are less infectious than unvaccinated individuals.

We downloaded the supplementary data from GitHub (where academics often store their computer code) to examine the country-specific estimates and assess the plausibility of the numbers for the UK, Italy, and the USA.