https://gnews.org/1503749/

07/09/2021 Prof. Sucharit Bhakdi: The immune system can make many components. When it meets a new virus, it will make an antibody IGM. If it has seen this virus before, and remembers it, then it quickly makes other antibodies, IGG and IGA. The antibodies can try to prevent the entry of the virus into yourself.
They are called protective antibodies, they can protect the cell from getting infected by the virus.
If however, the cell does get infected, then lymphocytes are there behind the scenes that will come out and recognize that the cell is infected. And these killer lymphocytes have the duty to kill the cell. So once the cell is killed, the virus factory is destroyed, the virus can’t be produced anymore.