Dan Glaser, CEO of Marsh & McLennan Companies, told CNBC on Thursday he does not anticipate coronavirus vaccine mandates to be widely implemented by employers.In a “Squawk Box” interview, Glaser said corporate America fully recognizes the importance of vaccines in curtailing the pandemic. “Don’t get me wrong: CEOs want their employees vaccinated, but I think that mandates are going to be very rare,” he said.Still, Glaser, who has led the New York-based consulting firm and insurance broker since 2013, said Marsh & McLennan is advising clients to “strongly encourage” vaccinations against Covid-19. “We all want to return to a more normal way of life … and vaccines are really required for that,” he said.The first Americans outside of clinical trials began receiving Covid-19 vaccinations last week, and health-care workers and long-term care facility residents are receiving priority in the initial wave of available doses.It will still take time before vaccines are widely available for the general public, Glaser noted, which is an important piece of the puzzle for companies as they consider policies. “That’s still a ways off, particularly when you think on a global basis,” he said.”Generally, any mandate should actually be government action as opposed to individual companies,” he added. “If we leave it up to companies, there will be tremendous variability, and that defeats the whole purpose of wide, wide vaccinations.”Earlier this week, Chipotle Mexican Grill CEO Brian Niccol told CNBC the company did not currently plan to require employees be vaccinated against Covid-19. Social media giant Facebook reportedly will not require vaccinations in order for employees to go back into the office. Ford and General Motors also have said they will not issue vaccination mandates.However, a poll from Yale University’s Chief Executive Leadership Institute suggests there could be some willingness among some C-suites to mandate Covid-19 vaccines. Just over 70% of CEOs surveyed at a recent summit said vaccines should be required by companies at work, according to data shared with CNBC by Jeffrey Sonnenfeld, who led the virtual gathering of executives.There is some question about whether companies could mandate Covid-19 vaccinations currently because the Food and Drug Administration has only issued emergency use authorizations, which are not the same as full approvals. That is why UAB Health System in Alabama is not mandating it, CEO Will Ferniany told CNBC on Dec. 17. However, if full approval is later granted and companies do decide to implement vaccination requirements, legal experts told CNBC earlier this month, employees who refuse to be vaccinated could be fired.Glaser said there is no question about the importance of widespread immunizations for the resumption of economic activity. “I’m just telling you the reality that I do not believe, from the companies we are talking to, that there is an appetite for mandates for vaccinations,” he said.