The injected vaccine then stimulates the immune system to produce antibodies and T-cell immune responses. The Vaccine Doses: The vaccines from each of the three companies require two doses. Each dose consists of 30 mcg for Pfizer and 100 mcg for Moderna, while for Novavax, each vaccine dose consists of 5 mcg of NVX-CoV2371 and 50 mcg of Matrix-M1 adjuvant that are co-formulated. The interval between the two doses — the priming and booster dose — is 21 days each for Pfizer and Novavax and 28 days for Moderna.