How long does it take for the COVID-19 vaccine to work?

It typically takes a few weeks for a vaccine to work. That’s how long your immune system needs to produce antibodies against a virus. Sometimes after vaccination, the process of building immunity can cause mild symptoms, such as fever. These symptoms are normal and a sign that your body is building immunity as it should.*

*https://www.cdc.gov/coronavirus/2019-ncov/vaccines/different-vaccines/how-they-work.html