Nearly three years since the pandemic gripped the globe, concern over evolving variants and superspreader events have kept about 3 million people out of the workforce, finds a new paper from the National Bureau of Economic Research by WFH Research heads Nicholas Bloom, Jose Maria Barrero, and Steven Davis. That gap in the workforce has slashed the U.S.’s economic output by a quarter of a trillion dollars in just the first half of this year alone. 

Between February and July 2022, 55% of respondents to the researchers’ Survey of Working Arrangements and Attitudes (SWAA) said they wouldn’t be returning to pre-COVID activities such as dining indoors or taking a crowded bus or train—and therefore would be staying out of the workforce. The researchers characterize that behavior as “long social distancing,” an extension of early-pandemic habits. 

“People with a cautious bent or with underlying health conditions that place them at higher risk of death or serious illness from COVID-19 can find sound, understandable reasons to continue and even intensify their social distancing practices,” Barrera, Bloom, and Davis wrote, adding that the effects of long social distancing are likely to persist for months or even years.

They cited a 2020 survey about COVID risk perception, which found that personal experience—or that of friends and family members—with COVID-19 makes people fear significantly higher risks. To that end, “preventative health behaviors” like social distancing and mask-wearing is most common among people who have seen how dangerous COVID can be. 

Older, lower-earning women with minimal formal education are the most likely group to partake in long social distancing, they found, especially those in areas with fewer remote work opportunities. 

It’s been well-established that those with college degrees are much more likely to work in roles amenable to remote work, rather than those that necessitate face-to-face contact. “Thus, it is much easier for the highly educated to practice full or limited social distancing while remaining employed,” the paper says. “In addition, because of their higher earnings, well-educated persons can more readily avoid commuting modes that involve a high volume of close encounters with others.”

Bad timing for the COVID-cautious

While the paper centers on those missing from the workforce, COVID fears might also explain why some workers are insistent on continuing to work from home.

The latest COVID variants are reportedly able to circumvent vaccines designed for earlier strains—and few people have gotten the latest booster. On a social level, many workplaces have altogether done away with COVID-era restrictions, and most major cities have dropped mask and even vaccine requirements. 

Since Labor Day, employees at Goldman Sachs have been allowed to enter the office regardless of vaccination status and haven’t been required to test or wear masks. “With many tools including vaccination, improved treatments, and testing now available, there is significantly less risk of severe illness,” the famously pro-office bank said in an internal memo.

That makes it much more difficult for immunocompromised or particularly COVID-conscious workers to commute into work and take in-person meetings without being at risk. 

For workers in that boat, Jim Link, chief human resources officer at the Society for Human Resources Management, encourages open communication with bosses about expectations and comfort level.

“That back-and-forth really opens the lines to trying to make the best decision for the culture of that company, the work that needs to get done, the success of that business, and the employees’ needs and desires and capabilities,” Link told Fortune Well. “That discourse and dialogue we believe will produce the best outcome for both the organization and for the employees within it.”