Common human coronavirus generally causes a mild to moderate upper respiratory infection. It is the third leading cause of the common cold. Young children are more likely to get infected, but infections can occur multiple times throughout their lifetime. Symptoms of the common coronavirus include runny nose, sore throat, headache, fever, cough, and general malaise. Common coronavirus can also cause severe lower respiratory infections in infants, older adults, and those with compromised immune systems. Transmission generally occurs with close contact with someone coughing or sneezing, touching contaminated surfaces, and touching your face.
Coronavirus is an enveloped positive-sense RNA virus in the Coronaviridae family. This virus is smaller, with a 60–125 nm diameter, and has a glycoprotein "spike" (S) and hemagglutinin esterase on the surface. The spike protein binds to the host cell. Seven coronavirus types are recognized, including MERS-CoV, SARS-CoV, and SARS-CoV-2.
In addition to the symptoms associated with common coronavirus infections, SARS-CoV-2 symptoms can also include shortness of breath, difficulty breathing, a new loss of sense of smell or taste, and nausea, vomiting, or diarrhea. These enhanced symptoms are related to the spike proteins on the virus that can mutate or morph into different shapes to elude detection and improve attachment to the host cell.
Figure 3. PHIL Public Health Domain/Eckert, A., & Higgins, D. (2020). This illustration, created at the Centers for Disease Control and Prevention (CDC), reveals ultrastructural morphology exhibited by coronaviruses. Centers for Disease Control and Prevention. https://phil.cdc.gov/Details.aspx?pid=23313
