The number of doses needed depends on which vaccine you receive. To get the most protection:
Two Pfizer-BioNTech vaccine doses should be given 3 weeks (21 days) apart.
Two Moderna vaccine doses should be given 1 month (28 days) apart.
Johnson & Johnsons Jansen (J&J/Janssen) COVID-19 vaccine requires only one dose.
If you receive a vaccine that requires two doses, you should get your second shot as close to the recommended interval as possible. However, your second dose may be given up to 6 weeks (42 days) after the first dose, if necessary.. You should not get the second dose earlier than the recommended interval.