The common cold is a viral infection of the upper respiratory system (nose, throat, sinuses, Eustachian tubes, trachea, larynx, and bronchial tubes). Rhinoviruses cause about 30%-50% of colds. However, more than 200 different viruses may cause the common cold. Colds are contagious, can spread from person to person, and have an incubation period of about 1-7 days. A cold’s duration (how long it lasts) is about 7-10 days. However, depending upon the viral strain, a cold can last up to 2 weeks. Colds are a mild upper respiratory illness with a runny, stuffy nose without fever. Doctors mainly diagnose colds using clinical observation and medical history. No tests are necessary.
Influenza (commonly termed the flu) is a viral infection of the upper respiratory and/or lower respiratory system. Influenza viruses cause the flu. These viruses usually cause more serious symptoms in the respiratory system than cold-causing viruses. The flu is contagious, can spread from person to person, and has an incubation period of about 1-4 days. The flu’s duration varies from about 5 days to 2 weeks depending upon the severity of the infection. The flu can become an intense and potentially fatal illness (pneumonia) in some individuals. Hallmarks of the flu include mild to high fever, moderate to severe headache, cough, fatigue, and body aches/pains. Severe flu may have symptoms that develop rapidly and require supportive care. Doctors diagnose the flu based on clinical symptoms and by readily available lab tests.
COVID-19 (2019 novel coronavirus)
COVID-19 (also termed the Wuhan coronavirus, 2019 novel coronavirus, 2019-nCoV, and others) is a single-stranded, positive-sense RNA coronavirus. It is a new strain of coronavirus (the term corona means crown) responsible for causing a pandemic of serious respiratory problems that started in Wuhan, China. Researchers believe it originated from infected animals and jumped over to infecting people in a large open seafood/animal market. Also, it has been able to spread from person to person and is rapidly spreading worldwide. It is related to the SARS and MERS coronaviruses. It has an incubation period ranging from 2-14 days. Person-to-person spread may happen even if the infected person has no symptoms during the incubation period. Infected people may also not be aware they have the virus and may not show symptoms. The main symptoms of COVID-19 are fever (usually high), moderate to severe coughing, and shortness of breath. Other symptoms and signs may include a sore throat, diarrhea, body aches and pains, and a stuffy or runny nose. At first, it seemed to target people over 60 years old and have severe underlying health conditions like heart disease, lung disease, and diabetes, but recent data from Italy suggests that people 20-60 years of age may get the disease at about the same rate. About 80% recover without specific treatment, while about 20% may require some respiratory support (oxygen and/or ventilator support).