COVID-19 Testing, from PCR to Antigen and Antibody


COVID-19 testing is often referred to as one thing by many people. In reality, more than 200 tests have been authorized by the U.S. Food and Drug Administration (FDA), to detect COVID-19 virus-related infections.

PCR tests

Most COVID-19 testing in America is currently done using polymerase chain reaction technology (PCR). These tests look for genetic material in a sample, which is most commonly taken via a throat or nose swab. False negatives are more common with COVID-19 tests than false positives. If you receive a positive result, it is very likely that you have the virus. You should self-isolate if you have coronavirus symptoms and/or recently met someone with the virus.

Saliva tests

Coronavirus saliva day 2 and 8 test are a novel type of PCR diagnostic for COVID-19. Mehta states that saliva testing is dependent on standard PCR technology and requires some manual labor to move the sample through the tests. Mehta states that collecting spit is easier than a throat or nose swab, and can be done at home without any medical training. SalivaDirect, a Yale test, does not require any proprietary chemical reagents, nor test tubes. This will allow for easier supply and access.

Antigen tests

Antigen tests can deliver results in minutes, but speed is not without its limitations.

Antigen tests are similar to PCR tests. They usually require a nose and throat swab. Antigen tests are different from PCR tests which search for genetic material of the SARS-CoV-2 viruses. Instead, they look for proteins on the virus’s surface. Because there is less chemistry involved in this process, it is less labor-intensive and also more sensitive than PCR testing. Mehta states that false positives can occur if the test detects proteins similar to those found in SARS-CoV-2, or negatives if it misses any proteins. False positives with antigen testing are very rare, but half of all negative results are inaccurate. Your doctor may order a PCR test if you are negative, but still have symptoms or have been exposed to risky substances.

Antibody tests

Antibody tests, unlike the other tests mentioned here, are not meant to detect current SARS-CoV-2 infection. They look for antibodies in the blood, which are proteins that the body produces in response to infection. These antibodies may give immunity against future infections. These tests check for antibodies specific to SARS-CoV-2 in order to determine if you have had coronavirus.

Antibody tests are currently unable to do anything other than satisfy curiosity. False results are quite common, Mehta states. Scientists don’t know how effective or long the coronavirus antibodies can protect against COVID-19. However, a positive antibody test does not necessarily mean that you are immune to COVID-19. At least, this is what current science shows.

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