Booster COVID-19 Pfizer and Moderna vaccine available for 70+ 6 months after second dose . You can book your booster vaccine if you received your second dose in April or prior to April 2021. Booster is also available for health care worker 6 months after second dose. Third dose is available for people with immunosuppressive conditions or taking immunosuppressants. The third dose can be given 8 weeks after their second dose in that population.