Explanation:

• Diseases such as covid-19 and influenza can be fatal due to an overreaction of the body’s immune system called a cytokine storm.
• Cytokines are small proteins released by many different cells in the body, including those of the immune system where they coordinate the body’s response against infection and trigger inflammation. The name ‘cytokine’ is derived from the Greek words for cell (cyto) and movement (kinos).
• Cytokine storms are a common complication not only of covid-19 and flu but of other respiratory diseases caused by coronaviruses such as SARS and MERS. They are also associated with non-infectious diseases such as multiple sclerosis and pancreatitis.