Colds are caused by many different viruses, but most commonly a rhinovirus or coronavirus. A cold is also a viral infection, but it only affects the upper respiratory tract (nose and throat) instead of the lungs. While patients may feel miserable when they have a cold, the symptoms are generally mild compared to more aggressive viruses like the flu. A typical cold will last on average 7-10 day. Contagious for 1-2 days before symptoms start, patients with a cold could be contagious as long as their symptoms are present – in rare cases, up to two weeks.
With a fast onset, seasonal flu is a common respiratory infection caused by a virus that affects the nose, throat, and lungs which generally last 5-7 days. Patients with flu are most contagious in the first 3-4 days after their illness begins.
Covid-19 is a respiratory illness caused by SARS-CoV-2. Many people experience mild symptoms, while some experience no symptoms at all. Most people who develop Covid-19 symptoms improve without treatment in 2-6 weeks. However, this does not necessarily reflect how long the virus itself remains active in the body.