Both the Pfizer-BioNTech and Moderna vaccines require two doses given several weeks apart. The first shot helps your body begin to build protection. The second shot a few weeks later gives your body the most protection the vaccine has to offer. Some individuals may benefit from an additional dose or a booster dose of the Pfizer-BioNTech vaccine, especially if they have a condition that severely weakens their immune system. Please follow up with your healthcare provider for additional information on whether you need more than two shots.