Antibody tests do not show whether a person is currently infected. A molecular (PCR) test is a more reliable indicator of current COVID-19 infection.
Antibody testing by itself should not be used to establish the presence or absence of COVID-19 infection or reinfection. Individuals might get tested too early before antibodies develop, and some individuals never develop detectable antibodies following infection. Additionally, having antibodies may indicate a previous infection and may be unrelated to the current illness.