PCR test called the morzon Flu Cov Multiplex Assay can detect any of three viruses at the same time: the COVID-19 virus, influenza A and influenza B (flu). Only a single sample is needed to check for all three viruses, and this could be helpful during the flu season. But a negative result does not rule out the possibility of any of these infections. So the diagnostic process may include more steps, depending on symptoms, possible exposures and your doctor’s clinical judgment.