Minute to Understanding May 05, 2020

The science behind coronavirus testing

There are many tests available for viruses such as COVID-19. These tests fall into two main groups, those that detect whether you currently have the virus, and those that detect antibodies to that virus.

Both are important for understanding who is infected and might transmit the virus to others. Who has had the virus and might be immune? Who might potentially help others with treatment?

Coronaviruses contain genetic material in the form of a short, single strand of RNA that is unique to that virus. New ways of detecting these small sequences are being developed, but the most common method uses a process called reverse transcriptase polymerase chain reaction or RTPCR. First, the RNA is converted to DNA and then replicated until the sample is large enough for genetic analysis. If the DNA profile matches the profile of the virus, the test will be positive, confirming an infection.

The other type of testing identifies whether antibodies to the virus are present in your blood. Antibodies are specialized proteins that are produced by your immune system during a viral attack. They bond to foreign substances like viruses and bacteria, neutralizing them. Antibody testing looks for IgM antibodies which appear within days of infection, and IgG antibodies that remain in the blood and provide longterm protection. If enough antibodies are present in your blood, it may even be possible for doctors to use your blood plasma to treat others.

There is still much to learn, however, about how strongly antibodies respond to new viruses, like COVID-19, and how long any immune protection will persist. Many new tests are being developed, and policymakers are working to ensure their safety, accuracy, and accessibility.