Flu, RSV and COVID-19 have many symptoms that are similar, but public health experts tell ABC News how you may be able to tell the difference between the three. ABC News. Video. Live. Flu, COVID-19, strep throat and respiratory syncytial virus (known as RSV) have similar cold-like symptoms, and they all affect the respiratory system, but there are some key differences. In this episode of House Calls: Real Docs, Real Talk, Dr. Eduardo Sanchez explains in detail the symptoms of these diseases, how they are treated, and how practicing good hygiene can prevent their spread. The spread of the flu, COVID, and RSV has driven respiratory-illness activity to high levels in New York City and 17 states — and vaccination rates for the three viruses remain far too low What is the difference between Influenza (Flu) and COVID-19? Influenza (flu) and COVID-19 are both contagious respiratory illnesses, but they are caused by different viruses. COVID-19 is caused by infection with a coronavirus (SARS-CoV-2) first identified in 2019. Flu is caused by infection with a flu virus ( influenza viruses). Symptoms of influenza (flu), respiratory syncytial (sin-SISH-uhl) virus (RSV), and COVID-19 are similar and may include fever, cough, and shortness of breath. Because the symptoms are similar, it can be difficult to distinguish between illnesses caused by respiratory viruses. To diagnose a potential case, healthcare professionals may use a jCJs.