Different vaccines work in different ways to provide protection. But with all vaccines, the body still has a supply of “memory” T lymphocytes as well as B lymphocytes that will remember how to fight that virus in the future.
It usually takes several weeks after vaccination for the body to produce T lymphocytes and B lymphocytes. Therefore, a person can become infected with the virus that causes COVID-19 just before or shortly after receiving the vaccine. -vaccinated and then get sick because the vaccine doesn’t have enough time to protect.
Sometimes after vaccination, the process of building immunity can cause symptoms, such as fever. These symptoms are normal signs the body is building immunity.
