For the BioNTech/Pfizer, Moderna and Vaxzevria (AstraZeneca) vaccines, two doses are required for full protection. Depending on the vaccine, you will receive the doses in the following intervals: BioNTech/Pfizer and Moderna 3-6 weeks, Vaxzevria (AstraZeneca) 11-12 weeks. Your body will start building antibodies after the first dose, and protection will be achieved about 3 weeks after. For full, sustainable protection, the second dose is required. After the second dose, it takes about 7 days for the body to build up sufficient protection from an infection. For the Janssen (Johnson & Johnson) vaccine, only one dose is required. Protection is achieved after about 3 weeks.