Molecular PCR Test: The Most Accurate Method to Detect COVID-19

Hundreds of COVID-19 tests have been approved by the FDA since the pandemic began. Molecular PCR testing continues to be the “gold standard” method for detecting COVID-19.

Since the launch of the COVID-19 pandemic in the United States, more than 46 million positive coronavirus test results have been reported to the US Centers for Disease Control and Prevention (CDC).

Regarding the detection of the virus that causes SARS-CoV-2, or COVID-19, the U.S. Food and Drug Administration (FDA) has included molecules in diagnostic tests that can show whether a person has an active infection. Molecules and antigens. Nick of the VERIFY viewer wants to know the tests that are considered to be the most effective way to detect active COVID-19 infections.


Are molecular tests more effective than antigen tests in detecting COVID-19 infection?

Source of information


Yes, molecular PCR testing is the most accurate method for detecting active COVID-19 infections.

What we found

According to Yale Medicine, molecular tests such as nucleic acid amplification tests (NAAT) and polymerase chain reaction (PCR) tests use sophisticated chemicals and equipment to replicate millions to billions of copies. , Search for genetic material in SARS-CoV-2 virus. Of virus-related DNA even from the smallest sample. Therefore, molecular tests are more sensitive and generally considered to be more accurate than antigen tests.

Antigen tests, sometimes called rapid tests, look for protein fragments in the virus. Antigen test samples are treated with reagents and are usually analyzed in the field by a medical professional. Unlike molecular testing, Yale medicine says that antigen testing requires a high level of virus in the test sample before the test is positive, which means that the antigen test can lead to false negatives.

“Sensitivity measures how often a test gives a correct positive result to people who are being tested,” Yale Medicine says on its website. “High-sensitivity tests capture almost everyone with the disease and do not produce many false-negative results.”

There are various ways to collect sample samples for the COVID-19 test, including nasal swabs, throat swabs, and saliva. According to the FDA, samples of nasal swabs are collected using short or long Q-Tip-like swabs. There are three ways to collect nasal samples: the anterior nares (nose), the middle turbinate, and the nasopharynx.

According to Yale University, the anterior nares method involves placing a three-quarter-inch cotton swab in the nostril and rotating it at least four times to collect the sample. In the middle turbinate method, a soft cotton swab less than an inch is placed straight back into the nostril to collect the sample. With the nasopharyngeal procedure, a medical professional inserts a long cotton swab deep into a person’s nostrils to collect water from behind the nose. Oropharyngeal (throat) swabs, on the other hand, are collected using the swab on the back of the throat, and saliva samples are usually collected by spitting into a tube.

Dr. Christopher D. Doan, Dean of Clinical Microbiology at Virginia Commonwealth University, said he would confirm that nasopharyngeal swabs can be unpleasant for some patients, but in terms of sensitivity they are “best”. He says it is considered the best.

“This is the gold standard,” says Doern. “We know it’s the best test in terms of picking up the most positive ones.”

According to Doern, scientific studies vary, but nasopharyngeal swabs usually detect an average of 10 out of 10 positive COVIDs-19 cases, but saliva, for example, 8 out of 10 positive COVIDs. -19 may result in cases. But he also says that it is necessary to take into account whether a person is showing symptoms.

Dr. Gerard Cangelosi, a professor of environmental and occupational health sciences at the University of Washington, who has helped develop non-invasive screening methods for the detection and diagnosis of COVID-19, said nasopharyngeal swabs could be the “gold standard” method. It states that there is. When detecting COVID-19 positive cases, it is not always the most practical method for collecting sample samples from different populations.

“The gold standard usually applies to diagnostics. The term is used because it is the most sensitive and accurate method, but it is not always the best method because practical considerations need to be considered. Not always, “Cangelosi told VERIFY. “They are very invasive and uncomfortable. It’s difficult for patients because it’s basically deep in the nasopharynx, or basically at the base of the skull. It’s also done for healthcare providers. It’s difficult because you have to stand in front of the patient while you’re there, and the patient often coughs, sneezes, and curses. It’s not an easy process. ”

According to Cangelosi, “the most important limiting factor in finding COVID-19-positive cases is the frequency of testing,” not necessarily the method of collecting sample samples.

“There aren’t many places to sample. You need to sample frequently. People with active illnesses can be negative one day, positive the next day, and negative the next day. Virus Because the types of viruses go up and down during the day, “Cangelosi said. “To find someone who can infect a virus, you really need to test people very often.”

Cangelosi states that he prefers to use a less invasive nasal swab, such as the middle turbinate or anterior method, during the test because it is easier to collect samples more often than the turbinate method. ..

“It’s a bit less sensitive, but it can be collected more often. If you collect samples and test them more often, you’ll find more cases,” says Cangelosi.

Jason Feldman, CEO of Vault Health, a leading virtual healthcare platform, states that Vault offers nasal swab and saliva COVID-19 testing options to workplaces and schools across the country. Vault’s priority is to ensure accurate results from the tests, he says.

“The reason I started saliva testing is to make it easier for young children, family members, and people doing the test at home. Just spit on a tube and you’ll get a good sample. If the test asks you to take a nasal swab and take your own sample, it is difficult, especially if it is a deeper nasal swab, and it can also ensure proper sampling of biomaterials. Difficult .. If you don’t get the right sample. You don’t get the correct results. When you spit on a tube, the saliva contains so many viral substances that the tests we provide Is enough to make sure that is an accurate result, “says Feldman.

According to Yale University, most molecular test specimens are sent to the laboratory for processing the results and are usually available within 1 to 7 days, depending on the location. According to the CDC, laboratory-based tests such as molecular PCR tests have “generally high” test sensitivities.

Other articles on VERIFY: Yes, the COVID-19 rapid test at home is as accurate as the rapid test performed at the inspection site.

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Molecular PCR Test: The Most Accurate Method to Detect COVID-19

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