What makes the delta variant so surprising, and not surprising

The delta variant of COVID-19 has swept the globe. It’s now confirmed in at least 130 countries. It’s more transmissible, it’s fitter, and with that, new outbreaks have prompted governments from Australia to Japan to reimpose restrictions. New data on transmission also has US health leaders reassessing guidelines, too, and ramping up vaccine incentives. This back and forth over developments with the virus may seem really confusing. Host Marco Werman speaks with Dr. Michael Marks, a researcher at the London School of Hygiene and Tropical Medicine, about what scientists are learning about the variant.