For the past three years, COVID-19 has been wreaking havoc with businesses.

After the initial wave of disruption caused by global government mandates to work from home, then came the seemingly constant absences caused by workers catching the virus.

Despite the fact that most organizations have long reopened their doors for business and want to welcome employees back to the office, it seems that coronavirus has not got the memo.

Each month, research shows that more than a million people have called in sick since the pandemic began. But for some professionals, their covid symptoms are superseding the few days businesses set aside for being sick.

Now long COVID has its grip on America’s workforce, and new research shows that it is preventing many people suffering symptoms like brain fog months after being infected from going back to work altogether.

Long Covid: Too sick to work

The study, published in Jama Network, examined more than 15,000 COVID-19 patients aged 18 to 69 years old across all 50 states of the U.S. and found that 15% reported having long COVID symptoms ranging from dizziness to shortness of breath.

Of the 2,236 participants who reported experiencing long-COVID symptoms, 12% were unemployed, compared to an unemployment rate of 9% for those who didn’t.

Even when the researchers adjusted for sociodemographic factors such as age, sex, region, and race and ethnicity, they found that long COVID was associated with a higher likelihood of being unemployed.

Meanwhile, almost half of those experiencing long-COVID symptoms complained about cognitive-related symptoms like brain fog or memory impairment which was impacting their ability to work.

The research’s lead author, Roy Perlis, said that there’s a “tendency to dismiss these symptoms” but that the results suggest that cognitive symptoms are not only “important because they’re distressing to people, but they’re also important because they have real implications in terms of function.”

And the findings are in line with professor Danielle Sandsmark’s clinical experience at the Penn Neuro Covid Clinic, who echoed that “cognitive effects and fatigue are the primary reasons that I hear from patients as to why they are unable to return to their jobs.”

“Cognitive symptoms, in particular, are not associated with an outward, physical disability, but these data demonstrate that these symptoms are associated with a real-world effect, like going back to work,” she told Jama.

But long COVID sufferers want to work

A notable number of professionals exited the workforce following the pandemic—with work-life balance, long social distancing and searching for more meaning in life, cited as some of the many factors behind this trend.

Yet a rather grim reality that the research highlights is that actually, a sizable cohort of working professionals now consider themselves unfit to work, in the aftermath of contracting coronavirus.

Out of those who are currently unemployed due to the debilitating symptoms associated with long COVID, 40% of them were in full-time employment prior to the pandemic. In contrast, only 28% of the unemployed participants who aren’t experiencing long COVID were employed pre-pandemic.

And for the most part, long-COVID sufferers want to return to work with almost 58% currently looking for work.

The proportion of workers with long-COVID who want to work but still finding themselves unemployed points to an imbalance, which the report suggests is down to workplaces not offering suitable adjustments for those with disabilities.

But it’s not all bad news. There are signs that long COVID may be on its way out—albeit slowly.

A recent Kaiser Family Foundation report using data from the Household Pulse Survey, a collaboration between several U.S. federal agencies, found that the percentage of people who reported active long covid symptoms has declined since June 2022, from 19% to 11% in January 2023.

“I certainly think that what we are seeing clinically is that most people who do have long COVID are getting better over time—not always perfect, but better,” Sandsmark agreed.

This story was originally featured on Fortune.com

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