How many doses of a COVID-19 vaccine will be needed? Will a second booster dose be needed?
The number of doses of a COVID-19 vaccine that will be needed will depend on the type of vaccine that is administered. The coronavirus vaccines being studied are evaluating one or two doses. When giving two doses, they are usually given approximately one month apart. Since several vaccines are likely to become available over time, it is possible that some vaccines will require one dose while others may require two doses. It is also possible that over time, additional doses of vaccine may be needed to provide continued protection. It will take ongoing evaluation over several months and years to understand how our immune systems respond to this virus and how vaccines that become available assist in that response.