How long can I wait for the second COVID vaccine dose? What the vaccine shortage, rollout delays mean for Massachusetts Updated Feb 02, 2021; With the COVID vaccine in short supply nationwide, and states rushing to ramp up their ability to deliver doses, not all vaccine-eligible residents in Massachusetts may be able to secure an appointment in the coming weeks. If you’ve received your first dose of the Moderna vaccine, the Centers for Disease Control and Prevention recommends getting your second dose roughly one month after the first injection. For the Pfizer-BioNTech vaccine, federal health officials suggest getting the second shot at about the three-week mark.