Viral load is a measure of virus particles. It is the amount of virus present once a person has been infected and the virus has had time to replicate in their cells.
A higher viral infective dose or more viruses a person comes in contact with can result in a higher risk of infection, and in some cases, the infection may be more severe compared to others. Studies have shown the same to be true for other viral infections, such as influenza.
Dr Connor Bamford, Research Fellow in virology and antiviral immunity at the Wellcome-Wolfson Institute for Experimental Medicine at Queen’s, explains how a high infectious dose may lead to a higher viral load, which can impact the severity of Covid-19 symptoms.