PCR/RT-PCR testing

PCR tests (also known as “molecular tests”) are the gold standard in Covid-19 testing. PCR is the most reliable and widely available testing method.

PCR testing has three steps: Material collection, extraction, and PCR. Let’s examine them one by one.

  1. The collection stage consists of inserting a swab into the patient’s nose and/or pharynx, to collect material from their respiratory canal. After extraction, the sample will be sent for analysis.
  2. Extraction will be performed by laboratory technologists, who will extract the genetic material from the sample. This genetic material may or not include the virus’s genes.
  3. The sample will then undergo a Polymerase Chain Reaction (PCR). Basically, the technologists will use a PCR machine to “amplify” the DNA sample. This stage will also involve the use of chemicals. One of these chemicals will produce a fluorescent light if it detects the presence of the virus’s genetic material.

Results for PCR tend to be available within 72 hours.

The Science

A virus survives by producing copies of itself within the body of a host, be it a human or an animal. Therefore, a virus’s genetic material will be present in the host’s body.

Some viruses produce DNA, while others, such as SARS-CoV-2, produce RNA. PCR tests are designed to detect the SARS-CoV-2 RNA in the body of the host. Namely, in their respiratory canal.

Polymerase chain reaction (PCR) is the process of amplifying – or making many copies – of a short piece of RNA or DNA. PCR is used to detect a known sequence of RNA/DNA. Using very specific probes designed to bind the DNA sequence of interest, a short piece of DNA is amplified through many cycles of heating and cooling. PCR amplification allows scientists to determine if a piece of DNA is present in a sample.


Frequently asked questions

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How accurate are PCR tests?

PCR tests are considered the gold standard in Covid-19 testing. According to the FDA, these tests are so accurate that their results don’t need to be double-checked by repeating the test.

However, PCRs are the most accurate when conducted on patients that have been infected 5-7 days before the test.

Do PCR tests require previous preparation?

While some testing locations may recommend abstaining from eating or brushing your teeth before taking the test, it’s rarely mandatory. We recommend you contact your testing location for extra information.

Can PCR detect whether I’ve had Covid-19 in the past?

There are two types of Covid-19 tests: Diagnostic tests and antibody tests. PCR tests are diagnostic. That is, they aim to diagnose whether someone is infected with SARS-CoV-2 at the moment. Antibody tests, detect the signs of a previous Covid-19 infection.

What’s the difference between PCR, RT-PCR, and NAAT?

These terms are usually handled as synonyms. But it’s worth explaining their subtle differences.

RT-PCR (Reverse Transcription Polymerase Chain Reaction) tests involve amplifying and detecting the virus’s genetic material at the same time. These tests are slightly faster than regular PCRs.

A Nucleic Acid Amplification (NAA) is any process of amplifying nucleic acids. Nucleic acids are the building blocks of genetic material. Therefore, a PCR is technically an NAA.