A: Influenza (flu) and COVID-19 are both contagious respiratory illnesses, but they are caused by different viruses, per the CDC. As they are caused by different viruses, the tests for determining the presence of these viruses are very specific. The oral or nasal swab tests performed during COVID-19 testing help scientists identify the presence of a specific beta coronavirus, SARS-CoV-2. This is the virus that causes the respiratory illness COVID-19. While no test is 100-percent accurate, it is highly unlikely someone with a flu or cold virus would test positive for COVID-19 and not have the SARS-CoV2 virus.