Dr. Anthony Fauci and billionaire philanthropist Bill Gates talk regularly these days, and as you would imagine, they mostly talk about ending the pandemic.

More specifically, right now, "we're talking a lot about these variants and what that will do," Gates, whose Bill and Melinda Gates Foundation has committed $1.75 billion to the fight against Covid-19, told Frances Stead Sellers during a Washington Post Live Special Wednesday. There are multiple Covid variants, emerging from the United Kingdom, South Africa and Brazil, which spread more easily and quickly.