There are seven types of coronaviruses that are known to affect humans, all of which cause upper respiratory infections. These different types are categorized into two groups: those that cause mild symptoms and those which pose more serious risks.
The four common human coronavirus types that cause mild symptoms include 229E, NL63, OC43 and HKU1. Mild symptoms could include nasal congestion, sore throat, cough, headaches or fever.
Occasionally these common coronaviruses can cause complications in your lower respiratory tract, resulting in pneumonia. The risk of this is higher among infants, older adults and those with a weakened immune system.
There are three types of coronaviruses that pose more serious risks to humans including SARS-CoV, which causes severe acute respiratory syndrome (SARS), MERS-COV which causes Middle East Respiratory Syndrome (MERS), and SARS-CoV-2 which causes COVID-19.