I’m Unable To Receive The 2nd Dose On Day 21, What Is The Window Between Shots?

The second dose of the Pfizer-BioNTech vaccine may be given up to twelve weeks after the first dose following guidance from the UK’s Joint Committee on Vaccination and Immunisation. If an interval longer than the recommended interval is left between doses, the second dose should still be given. The course will not need to be restarted.