The San Francisco Chronicle: CDC's mask guidance may come as a 'psychological shock.' But here's the data behind it

The abrupt relaxation of mask guidance by the CDC on May 13 came as a surprise to many people, including public health and infectious disease experts who follow pandemic trends closely and weren’t expecting the move for another few weeks, or even months. Steven Goodman, MD, MHS, PhD, Stanford Medicine professor of epidemiology and population health, provides commentary.