MSNBC Craig Melvin Reports September 24, 2021 15:35:00
Doctors. the fda now authorizing a booster, a third dose of the pfizer vaccine. right now it's only approved for people ages 65 and up as well as those 18 and older at high risk of exposure to the coronavirus, or severe illness. we've got a question asking how do they know the vaccine is waning and not just more people being exposed due to relaxed mandates with the higher transmission of the delta? what do we know about that? >> this is a good question. you know, we've had a whole lot happen in the last week on booster doses for the pfizer vaccine. it's not straightforward. the evidence presen...