Rapid Testing has Potential to Give False Negative Results

Sevilla Tovar, News Editor

   Since the Omicron variant of COVID-19 hit, more and more people are reporting getting false negative results from rapid testing, resulting in giving infected people false sense of relief and creating a complication in fighting the global pandemic.

   According to the Food and Drug Administration (FDA), there are two tests that are commonly used to diagnose a person infected with COVID-19, the polymerase chain reaction, or PCR, and the antigen test, or rapid test (fda.gov).

   According to Harvard Health, “Antigen tests detect specific proteins on the surface of the COVID-19. They are sometimes referred to as rapid diagnostic tests because it can take less than an hour to get the test results” (health.harvard.edu).

   According to Healthline, “Although these tests provide quick results, they aren’t as accurate as laboratory tests because they require more of the virus in your sample to report a positive result. Rapid tests come with a high risk of giving a false negative result” (healthline.com).

   According to UC High Biomedical Science Teacher Leslie Wymer, “Rapid tests are unreliable for a multitude of reasons, which include user error and manufacturing defects. PCR tests detect the antigen, the virus, just like the rapid antigen tests. However, the PCR tests are exponentially more sensitive in detecting the virus, and therefore are much more accurate.”

   Rapid diagnostic tests have their benefits and drawbacks. According to the UMass Chan Medical school, they are significantly cheaper and more available than PCR tests, but since they can be performed outside of a professional medical setting, many people are misdiagnosed (umassmed.edu).

   One of the explanations behind incorrect diagnoses is due to the nature of the test. Since the test recognizes larger amounts of the virus, it is easily able to identify a symptomatic person. However, a person in the early stages of infection, someone that doesn’t have much of the virus inside their sinuses, could be overlooked (umassmed.edu).

   False negatives may also be the fault of the person administering the test. According to Gavi, The Vaccine Alliance (GAVI), “How carefully material was collected from the nose and/or throat could also influence the likelihood of an infected person testing negative [a false negative].” Since there are no medical requirements to conducting the test, there is always a chance that the test was taken improperly (gavi.org).

   According to research done regarding tests administered at Johns Hopkins Hospital, “Researchers estimated that those tested with SARS-CoV-2 [the strain of COVID-19 that gets people sick] in the four days after infection were 67 percent more likely to test negative, even if they had the virus. When the average patient began displaying symptoms of the virus, the false-negative rate was 38 percent. The test performed best eight days after infection (on average, three days after symptom onset), but even then had a false-negative rate of 20 percent” (clinicaloncology.com).

   There are many complications to an infected person receiving a negative result. According to the FDA, risks include: not receiving treatment, unintentional spread of the virus to potentially immunocompromised close contacts, and other unintended events (fda.gov).

   One of the most dangerous repercussions of false negatives is the possibility of spreading the virus. GAVI continued, “The average incubation period for COVID-19 is 5-6 days (although it can be up to 14 days), and researchers estimate that people become infectious 2-3 days before they develop symptoms.” If someone infected gets tested too early, they could receive a negative and continue to expose people without their knowledge.

   Many suggest only using rapid diagnostic tests as a first ruling to check for COVID-19. Healthline advised, “A rapid COVID-19 test can be a useful preliminary test to see if you have the virus that causes COVID-19. However, if you have symptoms and your rapid test comes back negative, it’s a good idea to confirm your results with a PCR test” (healthline.com).

   If someone has been told or suspect they have been exposed to the virus, the best course of action for them would be to self-isolate until they either are symptomatic (when either test could diagnose them) or are able to receive a PCR test (healthline.com).