CNN host Erin Burnett said to Reiner "when you look at this in the broader context, there's still a third of the eligible population in the United States that hasn't got a single dose."
"Given where things are going, is it time to move on from saying please to mandating?" Burnett asked.
Reiner replied "I do think it's time to start mandating vaccines. And I think that the private industry and private organizations will do that."
"At GW university, where I work, starting in fall, you can't be on campus unless you're fully vaccinated," Reiner added.
He continued, "We're at the part of the pandemic now where the problem in this country is that 150 million Americans are not vaccinated. Half of that number is less than 18 years of age. But let's look at the adults. Seventy-five-million adults have chosen not to get vaccinated. That choice has consequences."
Reiner noted that the government cannot physically force vaccinations on people (for now), but advocated making it basically impossible for those who choose not to take it to live their lives normally.