The latest developments around Covid could very well kill the return-to-office date as we know it, business and health experts say.

"These RTO dates are now history," Nick Bloom, a Stanford Graduate School of Business professor who researches remote work, tells CNBC Make It. "Everything is completely off."

Covid-19 caseloads are rising again throughout the country. Meanwhile, research about the new omicron variant indicates it's highly contagious and a cause for concern. Health experts warn that rising caseloads, coupled with holiday travel plans, will likely lead to a surge in cases in the coming weeks that will overwhelm hospital systems.

Given how fast the state of the virus is changing, Bloom says any workplace reopening update "less than a week old is outdated. The whole concept of return-to-office dates doesn't make much sense."

He says many firms are now pulling out of the idea of setting a new return-to-office date altogether, as Google did when it delayed its office re-openings previously set for January. Lyft, an outlier, announced it will not require people to return in-person until 2023.

But for most employers, Bloom says CEOs should scrap any plans to bring workers back to offices in January and communicate that they'll revisit the idea mid-month after the holiday travel season. From there, if low Covid caseloads and rates of transmission permit it, they might consider reopening in early February with an optional return, and scale up to a full return through the end of March.

Some workers will need a longer lead time to plan their return, such as parents in charge of school or caregiving responsibilities, and people who've moved away but plan to return.

An extended return timeline has another benefit: Employers planning to issue a vaccination requirement must give employees enough time to get vaccinated, says Dr. Perry Halkitis, dean of the Rutgers School of Public Health. Even those who have received their full dose may have trouble scheduling a booster shot, which is now recommended as a means of slowing the spread of the Covid variants.

"I'm a firm believer that we should not be allowing people who are unvaccinated to enter public spaces, including the workplace," Halkitis says. "If I'm going into an office, I want to go to to an office where I know people must be vaccinated."

Businesses must also be flexible and consider workers who have children in schools and day cares, where outbreaks can lead to caregiving challenges, and those who have kids under 5 who are too young to be vaccinated.

Rather than rush to set a new return date, leaders should be using this period of uncertainty to set expectations, says Kate Bullinger, CEO of the management consultancy United Minds, which advises Fortune 500 clients on organizational change. "It's impossible to predict what the winter will bring," she says. Instead, she advises leaders commit to continually assessing the situation, health guidelines and employee sentiment, using all three to communicate any updates on a return timeline.

From a human behavior standpoint, Halkitis adds employers should take time granted with new return-to-office delays to make sure they're considering not just when, but also how, workers want to return, especially regarding how much time they'll be expected in-person versus when they can work from home.

A trickier question is what firms should do if they've already welcomed people back in-person for months. Bloom recommends employers send workers back home for the holidays around the weeks of Christmas and the New Year, if they haven't already, to slow the spread — and concerns — of the virus.

CEOs may be reticent to pull back on plans or project an air of uncertainty, Bloom says. But refusing to give space to the virus's spread and people's concerns could do more harm than good. "They say the hardest three words for a CEO to say are 'I don't know,'" Bloom says, "but those have to be used, because you're dealing with adults who have their own information."

"We saw what happened when leaders projected false confidence in May or June 2020," Bloom says, "but we've all learned the best policy is just being honest with employees."

Check out:

Omicron Covid variant: Is it safe to return to the office in-person?

How the omicron variant could impact return-to-office plans

For many workers, the return to offices has become ‘The Great Wait.’ It’s costing employers millions

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