A positive PCR test means that you are currently infected with COVID-19 and can spread COVID-19 to others.
Antibody tests check to see if you’ve developed antibodies against COVID-19, which occurs after being exposed to the virus. Antibody tests do not show whether a person is currently infected. It usually takes around 10 to 18 days after COVID-19 infects you for your body to produce enough antibodies for detection in the blood.
Getting an antibody test too soon after being infected may cause a negative result that is incorrect (false negative). Additionally, some individuals who are infected with COVID-19 may not develop detectable levels of antibodies, such as those with weakened immune systems due to a medical condition or certain medications.