What is "PCT Test"

PCR tests detect the presence of the virus's genetic material using a technique called reverse transcriptase polymerase chain reaction, or RT-PCR. For this test, a sample may be collected through a nasal or throat swab, or a saliva sample may be used.

The sample is typically sent to a laboratory where coronavirus RNA (if present) is extracted from the sample and converted into DNA. The DNA is then amplified, meaning that many copies of the viral DNA are made, in order to produce a measurable result. The accuracy of any diagnostic test depends on many factors, including whether the sample was collected properly, when during the course of illness the testing was done, and whether the sample was maintained in appropriate conditions while it was shipped to the laboratory. Generally speaking, PCR tests are highly accurate.

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How reliable are the tests for COVID-19?

The PCR test has been the gold standard test for diagnosing COVID-19 since authorized for use in February 2020.

The accuracy of any diagnostic test depends on many factors, including whether the sample was collected properly. For PCR tests, which are typically analyzed in a laboratory, test results may be affected by the conditions in which the test was shipped to the laboratory.

Results may also be affected by the timing of the test. For example, if you are tested on the day you were infected, your test result is almost guaranteed to come back negative, because there are not yet enough viral particles in your nose or saliva to detect. The chance of getting a false negative test result decreases if you are tested a few days after you were infected, or a few days after you develop symptoms.

Generally speaking, if a test result comes back positive, it is almost certain that the person is infected.

If you experience COVID-like symptoms and get a negative PCR test result, there is no reason to repeat the test unless your symptoms get worse. If your symptoms do worsen, call your doctor or local or state healthcare department for guidance on further testing. You should also self-isolate at home. Wear a mask when interacting with members of your household. And practice physical distancing.