* Fourth, the authors discuss only a single case of someone with a false-negative antibody test because the patient was taking a potent immunosuppressive drug (
mycophenolic acid, used to prevent organ rejection in some transplant patients). (I previously have said that such cases are theoretical, with few if any actual reported cases. My belief is now confirmed, and in particular people need not worry if they are taking mild immunosuppressive medications, corticosteroid creams, etc.