Viral load is the amount of a virus present in someone's blood. Also known as viral burden or viral titer, viral load determines whether or not that person will get sick, whether they will be contagious and how sick they could get from the infection itself.
As a general rule, the higher the viral load in a person's blood or body, the higher the likelihood of the infection spreading in their body.
Viral load is measured in the amount of virus present per millilitre of blood. There are specialised viral load tests that are available to find out the extent of infection in a patient, or how much of the live virus is present in a person's body.
A viral load test has been critical in the treatment of HIV/AIDS in the past, and more recently, during the COVID-19 pandemic in order to analyse not only how severe the infection may be in a patient, but also to understand how infectious a person is. A higher viral load also indicates how a person carrying a virus is able to spread it to other people through viral shedding.
Viral load in a person also indicates how the immune system responds to the pathogen invading the cells. As in the case of HIV/AIDS, a high viral load indicates that the CD4+ cells that are deployed to fight the infection have been destroyed, leading to a faster progression of the disease in the body.
Read more: What HIV/AIDS patients need to know about COVID-19
Usually, an increase in the viral load in a person's body indicates progression of the disease. The reverse is also true: the infection is suppressed if there is a reduction in the viral load. However, recent research into COVID-19 patients in order to find out more about the spread of the disease has yielded some interesting results.