of protection. so what people should do is make sure they go out and get their booster and be ready for the omicron variant when it becomeses more common in the u.s. >> there's a new preprint study which means it hasn't been peer reviewed yet but that study finds people who got pfizer and then got j&j as a booster are producing a strong immune response. and maybe better protected against more severe disease. so what do you think hearing that is the best course of action? should people who haven't gotten their boosters yet intentionally mix the vaccines? >> yeah, it's a great question. we've now got several studies on mixing and matching. i'd make two key points. one is we often have this idea, that somehow one vaccine is better than another. j&j vaccines are absolutely terrific. and they are absolutely, i think, as good as the mrna vaccines moderna and pfizer. if you want to use it as a booster, great. second, most of the evidence suggests it probably doesn't matter which booster you get. if you want to mix and match,