But new poll results suggest that employers so far have been cautious about enforcing such mandates.

About 14% of employers are already requiring vaccines among all of their workers, while 29% are considering implementing a companywide mandate, according to a survey of nearly 600 employers that global professional services firm Aon fielded Aug. 17–24. About 22% of companies report requiring vaccines for on-site employees. That’s up significantly from the roughly 7% of companies that Aon found were planning vaccine mandates back in the spring. 

“You're seeing a great deal of alignment across many sectors of the economy where employers have spoken up, basically in tandem with the U.S. government, saying they are much more comfortable mandating these vaccines,” Neal Mills, chief medical officer at Aon, tells Fortune. 

Yet despite a rise in vaccine mandates, corporations lack universal enforcement of those requirements. Nearly half of employers, 48%, report that they allow for religious exemptions, and 47% allow exemptions for health reasons. 

Even fewer companies are willing to terminate employees over these policies. Only about 7% of companies reported they would fire an employee who refused to get a COVID-19 vaccine. That percentage increased, however, among companies in industries that traditionally demand in-person work—although the majority still responded they would not terminate workers. In health care, for example, about 34% of employers say they would terminate an employee for refusing to get a vaccine, although the survey’s sample size in that industry was small. 

Balancing the need to keep workers safe against providing flexibility and accommodations is “extraordinarily difficult” for companies right now, Mills says. Instead, many employers are relying on alternatives to a vaccine mandate. In fact, 43% of companies considered implementing vaccine mandates and opted against them, Aon’s survey found. 

Overall, companies are employing diverse methods to handle unvaccinated workers. About 38% report they are extending available remote work options, while 20% are requiring periodic negative COVID-19 tests from unvaccinated employees. Nearly one in five companies are opting to limit the activities that unvaccinated employees can participate in on-site. 

“Employers have had to revisit what they are going to do for those that are not willing to get the vaccine,” Mills says, but he adds that these alternatives are not always easy to execute. He points out that companies looking to implement testing regimes, for example, are running into issues sourcing supplies right now. 

Companies can also employ safety protocols such as mask mandates and social distancing. Just over a third of employers reported requiring workers to wear masks and adhere to social distancing while on-site. “There are still more tools at employers’ disposal that they can use,” Mills says. 

Beyond implementing safety protocols in the workplace, Mills says employers need to pay attention to COVID rates in their communities, especially local hospitalization rates. If a company brings everybody back to work in-person and a portion of its workforce is unvaccinated, company leaders need to assess whether there are enough beds at local hospitals if an outbreak takes place. 

Over the next few weeks and months, Mills notes, companies will continue to evaluate and reevaluate their position on vaccine mandates. “There's a great deal of momentum toward more employers revisiting the decision and deciding that because [a mandate] could greatly minimize disruptions than that is a more appealing choice now,” he said. “There's still a lot on the table employers have to consider and work through here.”

More health care and Big Pharma coverage from Fortune:

• “Munchausen by Internet” and the dangers of self-diagnosing mental health issues on TikTok
• Why South Africa’s COVID outbreak is raising alarms
• The psychology behind why people will take horse paste, but not COVID vaccines
• Why more companies like Nike are closing their offices for a mental health break
• Commentary: Paid family and medical leave is a civil right