WE often assume that viral infections are caused by individual virus types. But in reality, we’re exposed to many viruses on a day to day basis, and co-infection – where someone is simultaneously infected by two or more virus types – is quite common. MATTHEW JAMES, Research Assistant, Wellcome-Wolfson Institute for Experimental Medicine, Queen's University Belfast The cells lining our throat and lower airways are exposed to the environment around us, making them a prime target for co-infection by respiratory viruses. These range from common-cold-causing rhinoviruses to the more serious influenza viruses, which are often the cause of global pandemics.…