Why face mask mandates for all should be back on the table

Last week, nearly every state in the U.S. experienced an increase in daily coronavirus cases. Driven by the Delta variant, this rise and an accompanying increase in hospitalizations have sparked a debate about returning to indoor mask mandates for all, regardless of vaccination status.

Los Angeles County announced Thursday that face masks will be required indoors for both vaccinated and unvaccinated people, and the state of Hawaii has maintained a similar requirement amid rising cases. However, officials in both New York City and Chicago recently rejected the idea of a new universal indoor mask mandate.

Are mask requirements again necessary in the U.S.? Our research shows why the answer is yes in many places: The unvaccinated are least likely to wear masks.