What is PCR? Polymerase chain reaction (PCR) is a common laboratory technique used in research and clinical practice to amplify, or copy, small segments of genetic material. PCR is sometimes referred to as "molecular photocopy" and is incredibly accurate and sensitive. Short sequences called primers are used to selectively amplify a specific DNA sequence. PCR was invented in the 1980s and is now used in a variety of ways, including DNA fingerprinting, diagnosis of genetic disorders, and detection of bacteria or viruses. Since molecular and genetic analyses require significant amounts of a DNA sample, it is almost impossible for researchers to study isolated pieces of genetic material without PCR amplification.
How does the COVID-19 PCR test work? The COVID-19 test uses a modified version of PCR called quantitative polymerase chain reaction (qPCR). This method adds fluorescent dyes to the PCR process to measure the amount of genetic material in a sample. In this case, healthcare workers measure the amount of SARS-CoV-2 genetic material. Sample collection Reverse transcription of SARS COVID-19
The testing process begins when healthcare workers collect samples using a nasal swab or saliva tube. The SARS-CoV-2 virus, which is the pathogen that causes COVID19, uses RNA as its genetic material. First, PCR is converted from single-stranded RNA to double-stranded DNA in a process called reverse transcription. Next, the two strands of template DNA are separated. Primers attach to the end of these strands. Primers are small pieces of DNA designed to bind only to a specific genetic sequence of the viral DNA, ensuring that only the viral DNA can be duplicated (right). Once the primers bind, new complementary DNA strands extend along the template strand. As this occurs, fluorescent dyes attach to the DNA, providing a marker of successful duplication. At the end of the process, two identical copies of viral DNA are created. The cycle is repeated 20-30 times to create hundreds of DNA copies corresponding to the SARS-CoV-2 viral RNA.
What do the results of a COVID-19 PCR testing mean?
A positive result occurs when the SARS-CoV-2 primers match the DNA in the sample and the sequence is amplified, creating millions of copies. This means that the sample is from an infected individual. The primers only amplify the genetic material of the virus, so a sample is unlikely to be positive if there is no viral RNA. If it does, it is called a false positive.
A negative result occurs when the SARS-CoV-2 primers do not match the genetic material in the sample and there is no amplification. This means that the sample does not contain any virus.
A false negative result occurs when a person is infected, but there is not enough viral genetic material in the sample for the PCR testing Lab to detect it. This can occur shortly after the person is exposed. In general, false-negative results are much more likely than false-positive results.
FAST COVID-19 TESTING With Official Travel Certificate
Globally recognized certificate suitable for international travel. Fast Lab Results
Results ready in 30 minutes, including approved QR code for travel. Approved By FDA & CDC We are a certified CLIA Lab with CAP Accreditation.