Until new drugs are found to treat COVID-19, one of the more effective treatments has been plasma therapy. Bill Whitaker reports on how doctors are taking the blood plasma of COVID-19 survivors, and the virus-fighting antibodies in it, to create the life-saving therapy; produced by Michael Karzis, Julie Holstein and Howard L. Rosenberg. Lesley Stahl reports on raw sewage that is entering Southern California’s coast lands and waters from Tijuana, Mexico, just over the border; produced by Shachar Bar-On and Natalie Peel. In the most ambitious Mars rover mission yet, NASA hopes to launch Perseverance this summer to find evidence of ancient life on the “Red Planet,” Anderson Cooper reports; Andy Court produces.