Pfizer COVID vaccine rollout could begin Dec. 11, federal official says … C. diff rates fell in hospital inpatients but remained steady in outpatients during pandemic surge … New Eli Lilly COVID treatment arrives as hospitals scramble to solve logistical challenges … FDA approves emergency use for baricitinib-remdesivir combo in COVID … Alzheimer’s plaques may be caused by ‘traffic jam’ in nervous system, scientists say