Some nine months into the COVID-19 vaccine rollout — and with the U.S. heading toward flu season with the Delta variant still circulating — only around 53% of the country’s population has been fully vaccinated.

So when the slower-than-expected pace of inoculation led the White House to mandate vaccination at private companies with 100 or more employees, it was represented by many pundits as a potential game-changing moment. Some 80 million employees — about two-thirds of U.S. workers — likely fall under the aegis of the executive order.

Public health experts and business leaders generally applauded Biden’s decision, noting that worker mandates are often quite effective in countering vaccine hesitancy. With most large companies requiring vaccination, the thinking goes, mandates may deter employees from quitting and trying to find work elsewhere to avoid inoculation.

“It’s very important to the public health of our country, not to mention our economy, to boost rates at which people are vaccinated,” noted Coalition for Healthcare Communication executive director Jon Bigelow. “It would seem to me that the Biden mandate is an appropriate measure, given that he has already tried persuasion. In today’s climate, that hasn’t been sufficient to raise vaccination rates high enough to protect public health.”

Betsy Booren, SVP of regulatory and technical affairs at trade group Consumer Brands Association, agreed. She believes a federal mandate will help streamline vaccination requirements for employers, especially in the wake of widespread confusion over COVID-19 restrictions and vaccine policy.

“A federal mandate provides a level playing field across employers and state lines,” Booren said.

But the mandate announcement came with precious few details. Among other important aspects, companies are wondering about the strategies that will be needed to ensure proof of vaccination, bearing the costs of weekly testing and potential implications for booster shots. On Monday, the Consumer Brands Association sent a letter to Biden calling for clearer guidance.

“The details of working this out are difficult. What do you do in the case of non-compliance? Do you discharge employees? Do you assemble work-from-home arrangements?” Bigelow asked. “And there is always the possibility you could lose some employees because of these mandates. All these things will work out differently at different companies.”

It’s likely that the Occupational Safety and Health Administration will do much of the heavy lifting and ultimately issue a new emergency temporary standard (ETS) to implement the mandate. The ETS will allow the federal government to enforce the mandate given that a “grave danger” to workers is still very much present. OSHA could penalize violations with thousands of dollars in fines.

Of course, it’s possible that the ETS will face considerable pushback, as several governors have already threatened to sue. And while it’s unclear how those legal challenges will play out, companies are currently more concerned with their own implementation strategies, which will include pandemic-era mainstays like social distancing, masking and improved ventilation.

Public health experts, on the other hand, are more acutely aware that the reality of the virus has morphed, literally and metaphorically. “There are many more factors that need to be considered today in terms of what the strategy may be,” said James Margiotta, SVP of sales at CVS Health’s Return Ready program, during a virtual panel on return-to-office policy last week. “We’re transitioning from a pandemic to endemic state. We’ll be living with the COVID virus for a significant amount of time, so when you think about the variations, many more will be needed to be taken into account.”

That could include considerations like the need for companies to decide how often they’ll test unvaccinated employees for COVID-19; whether they’ll continue to test fully vaccinated people for potential breakthrough infections; how they plan to educate employees to increase vaccine confidence; and how they will track vaccination status. Companies will also need to figure out the resources that are needed to execute their strategies, Margiotta added.

“Financial resources, testing resources, testing platforms, the geographic location to actually perform the strategy you want to deploy – there are many variables that, when you think back to where we were this time last year, there were much fewer that needed to be considered,” he noted.

To that point, most businesses are simply waiting on clearer guidance from the federal government.

“These questions are important and we don’t even have simple answers on how to track vaccination records and what’s considered a negative result and booster shots and natural immunity – all of which are fairly simple, but very complicated to get to the answers,” Booren said. “We all have those same questions and we just don’t know. Our questions aren’t unique just to our industry; these are questions every business is likely facing.”

Previous comments made by federal COVID-19 response coordinator Jeffrey Zients have suggested that the OSHA rule could take weeks to be fleshed out. For now, the Biden administration maintains that it will release more guidance on September 24 designed to guide federal contractors that would be affected by the mandate.

But Bigelow believes that, regardless of details or timing, the vaccine mandate will be necessary to get the country’s pandemic response up to speed.

“This is happening in the context that the U.S. as a country has risked missing an opportunity to get this pandemic under control,” Bigelow said. “It’s frustrating to watch because there have been a number of great successes along the way, and yet politicization of the process, misinformation and social media have gotten us in a situation where we haven’t gotten the levels of vaccination needed to protect public health.”