The Centers for Disease Control and Prevention (CDC) acknowledged Thursday that it is combining the results from viral and antibody COVID-19 tests when reporting the country’s testing totals, despite marked differences between the tests.
Viral tests — commonly referred to as PCR tests as most of them use a process known as polymerase chain reaction — are used by health professionals to determine whether or not a person is currently infected with the disease. Antibody, or serology, tests serve a different purpose. Unlike viral tests that are taken by nose swab or saliva sample, antibody tests examine a person’s blood to see if their immune system has created antibodies to combat COVID-19. These tests allow doctors to see if someone has previously been exposed to the virus. Serology tests are also less accurate than PCR tests, increasing the chances for a false negative.
The combining of the tests could lead to the skewing of the overall positivity rate of the test, a measurement that is one of the benchmarks used in the reopening guidelines released by the White House and CDC.
Read more at The Hill.