This week, Mark and Margaret take a look back at COVID’s hold on 2021, the early promise of vaccines, the relentless march of mutations and the vicious rise of new variants leading to pandemic surges around the world. They revisit conversations with memorable guests from famed virologists and epidemiologists like Paul Offit and Michael Osterholm, to President Biden’s COVID team leaders Rochelle Walensky, Anthony Fauci and Rachel Levine. They revisited guests focused on other health news: Bill McKibben on climate change, and Planned Parenthood President Alexis McGill Johnson on the existential threat to women’s reproductive rights in the U.S. It was also a year to celebrate the dramatic discovery underway in the field of science, with Eric Topol, William Haseltine and NIH Director Francis Collins.