To suppress the surge of the Delta variant, the US must convince a large block of the remaining tens of millions reluctant and recalcitrant unvaccinated adults to get a shot. Statements last week from some Republican governors including Kay Ivey of Alabama urging constituents to get vaccinated are a late, but welcome change. Other prospective events such as the anticipated full FDA approval of the Pfizer and Moderna Covid-19 vaccines may also persuade some of the undecided, but the most recent KFF poll found that 20% of the US population says they will either definitely not get vaccinated or will do so only if mandated.

As we work to increase vaccination, the United States should reinstate universal indoor masking. We should do this not to protect the vaccinated, for whom the risk remains low, but instead to protect the vulnerable, including the immunocompromised for whom vaccines are less effective as well as the children who cannot yet be vaccinated and the adults who still choose not to be vaccinated. Since the US does not have vaccine passports there is no way to distinguish the vaccinated from the unvaccinated and, as a result, the entire country must mask up once again.