When COVID hit, it sent major companies scrambling to protect their employees from a deadly pathogen and totally revamped the way they thought about worker health.

The worst days of the pandemic are fading, but it left a lasting impression on some companies about the importance of mental and physical health for their workforce. And in the last few years, several have hired for a new role that didn’t exist just a few years ago: chief wellness officer.

AT&T brought on an SVP of health and well-being in 2022. Professional services powerhouse EY hired a chief well-being officer in 2021, and management consulting firm Aon hired a chief well-being officer in 2022. Even the CIA hired a chief well-being officer last year. Other companies like Delta, which hired a chief health officer in 2021, are pivoting that role away from strictly medical oversight and into a broader—they would posit, more holistic—vision of wellness.

Fortune spoke with top wellness executives and experts who say that although the pandemic is waning, it highlighted the importance of employee health. Faced with the prospect of employee burnout and widespread mental health impacts of COVID, companies are turning to the new role as a way to retain workers and help employees.

AT&T hired Jeff Tzeng last year as its SVP of health and well-being after he did a five-year stint as chief medical officer at Comcast, which included the toughest part of the pandemic. Now his mission at the telecoms giant is to make the well-being of AT&T employees the central focus of the company across every division and program.

“The lack of social interactions contributed to feelings of isolation and increased mental health challenges. Some of our people were very open in sharing about these struggles and their desire to improve their well-being,” AT&T HR chief Angela Santone told Fortune. “Even as the pandemic waned, we knew we had to do something about these very concerning by-products of the public health emergency.”

The workers are not all right

In early May, a little more than three weeks after President Joe Biden signed a bill ending the national emergency designation for COVID-19, the U.S. surgeon general raised the alarm on another public health crisis: loneliness, our increasing isolation, and deteriorating mental health.

The preexisting loneliness epidemic, intensified by pandemic lockdowns and subsequent changes to our work and social lives, demands the same level of attention as “other critical public health issues such as tobacco, obesity, and substance use disorders,” Surgeon General Dr. Vivek Murthy said in a statement.

Rates of anxiety and depression rose significantly during the pandemic. In 2020 they skyrocketed 25% around the globe, according to the World Health Organization. And a survey from CNN/Kaiser found that rates of anxiety and/or depressive disorder among U.S. adults in February of this year was 32.3%, only a slight decrease from April 2020’s rate of 35.9%. People are now being asked to move on and return to working in an office, but the toll on their collective mental health hasn’t gone anywhere. More adults were in therapy in 2021 than before the pandemic, so much so that psychologists have struggled to meet the demand.

That anxiety and depression is following people into the workplace. Around 64% of 1,600 U.S. workers and HR leaders surveyed said they struggled with mental or behavioral issues, according to a March report from membership-based primary care practice One Medical. As a result, 91% of that cohort said they were less productive. And employers can’t afford to ignore these issues, according to Gallup, an analytics firm. Failing to invest in well-being equates to a loss of $322 billion in turnover and lost productivity costs per year globally due to employee burnout.

Henry Ting joined Delta Air Lines in 2021 as the company’s first-ever chief health officer. Delta CEO Ed Bastian handpicked Ting after the airline hired the Mayo Clinic, where he was previously a top executive, to advise on COVID-related cleaning protocols, ventilation practices, and in-air social distancing. But now his focus has turned to the health and well-being of Delta’s employees, and one of the central tenets of that right now is stress levels and mental health, he says. He’s helped expand the company’s mental health treatment offerings to include 12 annual free counseling sessions per issue that an employee may be dealing with, and access to therapists within four days. Last year, his team also prioritized bringing additional mental health vendors on board that focus on providing diverse therapists.

“This investment in holistic wellness is something we’re fully committed to,” he told Fortune. “If you enable your people to thrive, they will take care of your business.”

But what is well-being? And how do you measure it?

Companies seem to be more and more aware that their employees need additional physical and mental health support. But the role of a chief wellness officer is broadly defined, and there’s no clear measurement for how to judge their success.

HR executives have historically coupled benefit usage rates with employee satisfaction surveys to gauge whether employees are happy at work. But as well-being work continues to evolve, says Jen Fisher, chief well-being officer at Deloitte, there need to be more robust measures for employee health and wellness, along with understanding which policies actually help create a sustainable working culture.

Ting’s team at Delta launched an employee survey earlier this year that was initially developed at Harvard University’s Institute for Qualitative Social Science called the Flourishing Index to measure employees’ physical, emotional, social, and financial well-being. The company also conducted one-on-one interviews with workers to understand challenges and opportunities to their health.

Those initiatives have led to the airline hiring health advocates to make sure workers know what benefits are available to them, and how to access them. For example, Ting says, many employees did not know that their health care covers fertility treatments, as well as adoption and surrogacy costs. The company has also switched up its cafeteria offerings, providing vegan and healthier options.

Fisher, who was hired for her role way back in 2015, sees her job now more than ever as all encompassing. It includes delivering on company commitments to climate change, as well as diversity, equity, and inclusion goals, as a way of positively impacting employee well-being.

“Most organizations with all the best intentions have a significant focus and investment on DEI, on well-being, on climate and sustainability, on trust, health equity, all of these things that we care about as individuals and us as a society—but we’ve been looking at them almost in a siloed approach,” Fisher says. “Now is a pivotal moment for the people who sit in these varied roles across an organization to really start to come together and understand that these aren’t siloed areas that can be addressed separately. They really, truly need to be addressed together.”

Whether companies need to hire a chief to oversee wellness and well-being is an open question, says McKinsey senior partner Aaron De Smet, an expert on corporate culture who also advises leadership teams. But he adds that addressing employee wellness is important.

“Make no mistake, while the pandemic put a spotlight on the issue, the importance of it has not decreased,” he told Fortune, noting increased and persisting concerns about its impact on the mental, physical, and emotional health of employees. “Helping boost productivity and performance, ensuring accountability and delivering of results, while at the same time caring for sustainable and flexible lifestyles, positive employee experience, and employee burnout, well-being, thriving, etc., is likely to remain an important topic into the future.”

There’s only so much a chief wellness officer can do, though. The kind of ecosystem that Fisher and other well-being executives envision—one that makes employee well-being and satisfaction the most important aspect through every nook and cranny of the company—is likely to require everyone, from the chief wellness officer to the CEO and down to direct managers, to wave the well-being flag.

Simply relying on existing benefits and ad hoc solutions to address employee burnout and mental health, and boost well-being might not cut it—if it ever did before.

“We need to acknowledge that the way we’re working isn’t sustainable for humans right now. There’s a lot of things about work that need to change that may or may not ultimately be the responsibility of a chief wellness officer,” Fisher says. “These things need to sit truly within the C-suite to kind of relook at work and change systems that have been in place for a long time. Because the way we’re working and the way we want to work are so different. And those are the things that are having a more outsize impact on people’s well-being.”