The Centers for Disease Control's (CDC's) seemingly abrupt shift on indoor masking guidance for Americans who are fully vaccinated against COVID was really just a matter of time, given the groundswell of new U.S. cases over the past month. The CDC now recommends that people who live in areas where COVID cases are surging (especially due to the alarming rise of the Delta variant) wear masks in public indoor settings such as stores, restaurants, movie theaters, and other such venues even if they've already received two doses of the Pfizer or Moderna vaccines or a shot of Johnson & Johnson's coronavirus jab.

And that means American businesses large and small alike which have already whipsawed between wildly divergent and ever-shifting federal, state, and local guidance on indoor masking are in for another round of confusion on how to maintain public safety after many of them had already loosened their indoor mask requirements.

In its updated guidance mere months after indicating it was for the most part safe to stop strictly masking indoors once vaccinated, the CDC also followed the lead of the American Academy of Pediatrics (AAP) — which recently recommended that all students wear masks indoors when returning to school this fall — by suggesting that everyone from teachers to students to visitors and staff at schools should be required to wear masks regardless of vaccination status and irrespective of whether or not cases are surging in that school's surrounding community.

“The Delta variant is showing every day its willingness to outsmart us,” CDC director Rochelle Walensky said at a news briefing announcing the new recommendations. “This is not a decision we at CDC have made lightly.”

The trouble for businesses is that the CDC's recommendations don't have the full force of the law or an enforcement mechanism. It's still up to state and local governments to dictate what the exact legal requirements are for masking, and even then some locales may have law enforcement officials who don't plan on doling out repercussions for a failure to comply. That could easily lead to businesses simply playing things by ear as they wait for government action and feel out how strict enforcement measures might be (and how strict the businesses themselves want to be).

The CDC guidance outside of school settings recommends that all Americans wear masks in indoor settings in counties where there are more than 50 new COVID cases per 100,000 residents in a week. That encompasses some 46% of all U.S. counties that are grappling with high levels of community transmission and another 17% that are experiencing a substantial level of transmission. In Colorado, for instance, 38 out of 64, or 59%, of all counties meet the CDC's threshold for a surge in cases.

As of July 28, eight U.S. states—California, Connecticut, Hawaii, Illinois, Nevada, New Mexico, New York, and Washington—plus Puerto Rico and the District of Columbia have indoor mask mandates in place, according to the AARP. However, only Hawaii and Nevada require even fully vaccinated Americans to mask in public indoor settings, and Nevada's requirement was set to lapse on July 30 before the state reinstated a blanket mandate following the CDC announcement.

Locales in multiple states had taken it upon themselves to adopt the CDC's new guidance even before it was released, including Los Angeles County in California and Missouri's St. Louis County. Officials in Provincetown of Massachusetts' Cape Cod region held an emergency meeting over the weekend and reinstated its indoor mask mandate after a rapid surge of COVID cases following the 4th of July holiday. But even in regions that are begrudgingly accepting a return to indoor masking, local retail and small store owners may be forced to have awkward confrontations with people who are simply sick of masks, especially after a small taste of laxer protocols.

As for larger firms? Apple has already reversed its earlier position that fully vaccinated customers and employees don't have to wear masks in retail stores and is now requiring masks in areas with a growing case count. But many of the nation's largest chains are still mum on what they plan to do with the CDC's new guidance, especially big retailers that had loosened their in-store safety requirements for customers. That includes the likes of Walmart, Costco, and Target.

What these companies — and the states and locales in which they operate — plan to do will become clearer in the coming weeks. But what's certain is the chaotic dynamism of the COVID pandemic is once again heaping a lot of responsibility onto the backs of individual governments and business owners to quell what could become a devastating wave of Delta variant-driven COVID cases heading into the fall flu season.