Why Are COVID-19 Cases Really Falling?

Google mobility trends show we are still well below pre-pandemic trends for travel related to retail, recreation, transit, and workplaces, but there are no obvious declines in mobility since the beginning of the year, apart from brief weather-related dips in some states. But mobility trends may miss more subtle behavior changes such as fewer meetups with people outside one’s household or increases in mask wearing outside the home, and we have seen some favorable trends for those things, according to an ongoing survey conducted by Carnegie Mellon University. Together, all of this likely did contribute to reductions in the Rt—for one thing, we know these prevention measures have effectively crushed the flu (thought to be less transmissible than SARS-CoV-2) this year in both hemispheres.