Diagnostic tests determine whether a person has active COVID-19 cells invading the body. Medical professionals may use swabs to collect samples from nasal passages or take saliva samples.
Antigen tests attempt to determine whether the person has had COVID-19. If a person had the virus — even if there were no noticeable symptoms — he or she may have antibodies in their blood that were created by the body to destroy the attacking coronavirus. Studies suggest that these tests are not reliable because there are too many false negatives for people known to have had the disease. Blood samples are taken for this test.
The Ohio State University Wexner Medical Center hospital provides this article to explain how the tests are done.
In addition, the Wexner Center offers these pros and cons about tests for university employees that are applicable to all Ohioans:
Most reliable for diagnosis:
The COVID-19 polymerase chain reaction (PCR) test detects genetic material from the virus in a person’s body. (PCR is a process that rapidly duplicates the sample so that the genetic material can be examined.)
• Test is highly sensitive and can pick up miniscule amounts of the virus
• Highly accurate for people who are both symptomatic and asymptomatic
• Specimens are processed at trusted labs
• Tests take hours and patients may not receive results for days
• Requires special equipment and can be costly
Antigen tests to determine if a person has had COVID-19:
Commonly referred to as a rapid test, this diagnostic test can quickly detect fragments of viral protein. This test is similar to a rapid flu or strep test.
• Results on site within minutes
• Can be produced at a lower cost
• Positive results are thought to be highly accurate
• Scaling would allow rapid testing of large populations
• Less sensitive than PCR testing
• Higher chance of false negatives than other tests. Therefore, a negative result does not rule out infection. The FDA recommends follow-up PCR testing.