"I wear a mask to keep my patients safe," says emergency medicine physician Jeff Pothof, who received both doses of the coronavirus vaccine and yet he still wears a mask.
He says, "The last thing I want to do is take my patients who are already struggling with something and then get them sick with COVID-19."
Both Pfizer and Moderna's vaccine clinical trials found they were about 95 percent effective in preventing symptomatic and severe COVID-19 infections. But the studies didn't measure whether a vaccinated person is less likely to infect someone else.
"We don't have any good experience about whether or not it provides the kind of immunity in your nose and in your mouth that will keep you from getting a low-grade sort of transient infection with COVID in those spots that you might still be able to pass on to other people," says Dr. Emily Landon, an epidemiologist at the University of Chicago Medicine.
So until studies come out to prove that's not the case, mask up, says the CDC.
"This vaccine is mostly to protect you and not really to protect other people. So you still need to put that mask on," says Landon.
There are also lots of unknowns.
"With the vaccines, we know that there is protection offered up front, but we don't know how long that immunity will last," says Dr. Preeti Malani, the chief health officer at the University of Michigan.
New COVID-19 variants could also change the effectiveness of the vaccines. Malani adds,"Vaccination is happening slowly and until we reach a level of herd immunity where we really don't have transmission in the community. The recommendation is for everyone to still be wearing a mask."