You may hear the term “viral load” referred to in a HIV (Human Immunodeficiency Virus) education course, but term/concept may be more broadly applied to other types of viral infections including SARS-COV-2.
“Viral load” (VL) is a term used to describe the amount of virus (usually copies of virus or viral RNA) per unit volume. It is a measurement of concentration. Typically in medicine, VL refers to the number of viral copies per milliliter (mL) of blood.
Let’s think about some simplified examples. Let’s say there are 2 copies of virus-X in 1 mL of blood. That’s a LOW VL. It does NOT mean that there are no viruses in the blood; it just means a very low concentration. Another example, let’s say there are 10,000 copies of virus-X in 1 mL of blood. That is a considerably HIGHER VL.
The key to thinking about this is just because there is a low concentration of virus per unit volume of blood (i.e. low VL), it does NOT mean that there is NO virus there.
Why is this important? This is an important concept because many tests (including the test for HIV) have a concentration sensitivity level or range whereby the results of such a test are fairly accurate. If the VL is very low, the test for viral presence may not pick up the virus at all thus giving a false-negative.
VL may be very low and virtually undetectable if someone just contracted the virus (early stages of infection). In the case of HIV infection, antiretroviral protocol seeks to decrease the VL to such a low count that it is virtually undetectable.
Depending on the nature of the virus, knowing the incubation period would be helpful because one would want to test and retest the patient at the earliest possible opportune time, but also not too early.
References
Fletcher, J. (2018, November 29). HIV viral load: What it means, detection, and CD4 levels. Retrieved from https://www.medicalnewstoday.com/articles/323851#overview
