• Businesses should look to incentivize staff to get a Covid vaccine, rather than mandate it, Wharton School professor Nancy Rothbard told CNBC on Thursday.
• "There's a lot of challenges with mandating employees to do anything," she said.
• While many experts believe it's legal for employers to make vaccines compulsory, business leaders may worry about alienating staff.

Companies should encourage their employees to get vaccinated for Covid through incentives, not through mandates, according to Wharton School professor Nancy Rothbard.

"There's a lot of challenges with mandating employees to do anything," Rothbard said Thursday on CNBC's "Squawk Box." "Any boss will tell you, it's a lot more about persuasion than telling."

The issue of whether to require workers to get vaccines in order to return to the office has come into focus recently as about 3 million people in the U.S. per day are getting shots. The latest numbers from the Centers for Disease Control and Prevention show nearly a quarter of the American adult population is fully vaccinated.

While many experts believe it's legal for employers to make vaccines compulsory, business leaders may worry about alienating staff.

"Trying really to incentivize people to get vaccinated, I think, is going to be a much more popular route than mandates," said Rothbard, a management professor whose research partly focuses on work motivation and engagement.

Companies such as Tractor Supply are providing employees one-time cash payments to encourage them to get a Covid vaccine. Target is offering hourly employees up to four hours of pay — two hours for each dose for the vaccines from Pfizer and Moderna, which require two shots. Target also is providing help to pay for Lyft rides to and from appointments.

Johnson & Johnson's vaccine, the only other one cleared by the Food and Drug Administration for emergency use in the U.S., is only one dose.

Businesses should be mindful of employees' preferences around disclosing vaccine status, Rothbard said, adding some people are just less comfortable sharing personal information of any sort with employers and colleagues.

"There are ways to do this more privately, where you may want to take an employee aside and say, 'Look, have you been vaccinated? ... If you haven't, then we need to make alternative arrangements,'" for the safety of others, she offered.

The debate about vaccine disclosure in the workplace does not diminish the need for Americans to get inoculated to help bring an end of the pandemic, Rothbard said. "The term 'herd immunity' implies there is a collective cost to this, not just an individual decision people are making when they choose to get vaccinated."

Despite the importance, Rothbard stressed that incentives are likely to be effective in helping companies achieve high vaccination rates among their workforces.

"I have a paper that's called 'Mandatory Fun.' People do not even like having mandatory fun imposed on them if they're not feeling that is legitimate in the workplace," she said. "People don't react well to mandates. They react better to incentives and to encouragement."

Vaccine proof for customers

Whether customers should have to show proof of vaccination in order to obtain services at a business — such as eating at a restaurant, for example — has become another contentious issue in the U.S. Some critics are raising civil liberty concerns, while proponents of so-called vaccine passports say that requiring people to demonstrate they've been vaccinated benefits public health, allowing for a safe reopening of the economy.

Last week, Republican Florida Gov. Ron DeSantis signed an executive order that restricts businesses from requiring a customer to offer proof they've received a Covid vaccine as a prerequisite for service. In his order, DeSantis contends that Covid vaccine passports "reduce individual freedom and will harm patient privacy." 

Texas Gov. Greg Abbot issued a similar order Tuesday, banning state government and private entities that receive public funding from requiring Covid vaccine passports.

Dr. Scott Gottlieb, a former FDA commissioner, told CNBC on Wednesday that he believes the conversation around verifying vaccine status has been off base.

"I think we've been thinking about vaccine passports through the wrong lens. I think the way they're likely to be used is really to create two lanes of access to different venues," Gottlieb said in an interview on "Squawk Box." 

For people who cannot show they've been vaccinated, there could be required Covid testing along with secondary symptom screening, said Gottlieb, who now serves on the board of vaccine maker Pfizer.

"The other is going to be a fast lane, where if you can demonstrate you've been vaccinated you're not going to have to bring proof that you've been recently tested" or go through some sort of symptom checks, Gottlieb said. 

"It's going to be like an E-ZPass, where you can either go through the fast lane or if you still like to pay the toll booth because you think the police are tracking you with the E-ZPass device, then you can stop and stand in line and pay the toll booth," he said.

Disclosure: Scott Gottlieb is a CNBC contributor and is a member of the boards of Pfizer, genetic testing start-up Tempus, health-care tech company Aetion Inc. and biotech company Illumina. He also serves as co-chair of Norwegian Cruise Line Holdings′ and Royal Caribbean's "Healthy Sail Panel." The Associated Press contributed to this report.