The COVID-19 vaccine won't transfer during a blood donation. A blood donation isn't an effective way to get a COVID-19 vaccine. The blood you receive during a transfusion only contains red blood cells. Red blood cells don't contain any antibodies.
The antibodies your body makes that know how to fight COVID-19 after a vaccine are located in plasma. This means you'd need a plasma transfusion to receive COVID-19-fighting antibodies.
However, even a plasma transfusion is not a substitute for your own COVID-19 vaccine. Plasma transfusions are sometimes used to fight COVID-19, but they're not meant to be used as a preventive measure.
The antibodies from blood transfusions or plasma transfusions from a vaccinated donor aren't enough to provide COVID-19 immunity.