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Here Are The Types Of COVID-19 Tests You Can Take

Here Are The Types Of COVID-19 Tests You Can Take

With the third wave of the coronavirus taking over the country, the US has seen more than 13,9 million confirmed cases and over 273,000 deaths so far, the New York Times has reported.

According to Johns Hopkins data, the test-positivity rates have exceeded a World Health Organization-recommended threshold of 5% in the vast majority of US states.

With the rising number of COVID 19 cases across the US, doubts are being raised about the tests used for diagnosis and their ambiguity.

What has also caused doubts is the high number of false positives and false negatives shown by the tests. 

In a recent incident, Tesla Inc (NASDAQ: TSLA) founder Elon Musk took four rapid antigen tests and received two positive and two negative results. Musk called it “extremely bogus,” and he’s not wrong.    

Quest Diagnostics Inc (NYSE: DGX), one of the largest testing companies in the US, in a recent statement commented on the increasing number of cases, “Assuming national trends continue, we expect COVID-19 cases and corresponding orders for testing to increase for the foreseeable future, which may cause turnaround times to grow. The demand for COVID-19 tests rose 50% compared to six weeks before the rate of positivity rose to more than 10%.”

Talking about the demand for the coronavirus testing across the country, American Clinical Laboratory Association President Julie Khani says, “With demand for testing surging across the country, ACLA member laboratories are experiencing a significant increase in the volume of COVID-19 test orders. Clinical labs are also facing delays or cancellations on orders for critical supplies, such as pipette tips.” 

According to Julie, the laboratories could exceed their testing capacities with the increase in demand, resulting in significant delays.

Major manufacturers of the test kits in the US include Centers for Disease Control and Prevention (CDC), Wadsworth Center, New York State Department of Public Health, Roche Molecular Systems, Inc. (RHHBY: OTCQX), Thermo Fisher Scientific Inc. (NYSE: TMO), which the Food and Drug Administration(FDA) warned against in August, and Hologic, Inc. (NASDAQ: HOLX).

Here are the various types of tests being conducted for the coronavirus in the US at the moment.

Types of Tests: Primarily, there are two types of tests for COVID-19: the diagnostic test called “polymerase chain reaction,” or PCR, and Antigen tests, which detect parts of the SARS-CoV-2 virus. There are also antibody tests that sense molecules people produce after they have been infected by the virus. 

PCR Tests: The high-sensitivity PCR tests are considered to be almost 100% accurate in spotting infection when administered properly. According to the Centers for Disease Control, this is the so-called “gold standard” test for a clinical diagnosis. 

It is the most common test to detect SARS-CoV-2, the virus that causes COVID-19; it seldom gives a false positive. Its only downside is that it’s time-consuming.

Antigen Tests: Antigen tests, or the Rapid tests, give results in less than 30 minutes. This doesn’t have to be processed in any laboratory and is cheap to produce. Yet that speed comes with a cost insensitivity. 

Whereas a typical PCR test can detect a single molecule of RNA in a microlitre of the solution, antigen tests need a sample to contain thousands — probably tens of thousands — of virus particles per microlitre to produce a positive result.

This means that if a person has low amounts of virus in their body, the test might give a false-negative result.

According to MIT Medical, “Rapid tests or antigen tests — the COVID-19 equivalents of home-pregnancy or rapid strep tests. As with all rapid tests, there’s a trade-off between speed and accuracy. Besides, these tests were never intended to reliably detect infection in asymptomatic individuals.”

When Antigen tests are used as authorized, quick diagnostic tools, positive results are almost always accurate. This allows symptomatic people who test positive to be isolated quickly. 

But even when someone has a viral load high enough to produce symptoms of the illness, antigen tests have a false-negative rate of 10 percent or more. 

When this type of test is used on an asymptomatic individual, the likelihood of a false negative is even higher. 

False Positive: If a person does not have coronavirus but tests positive, the result is called “false positive.” 

As MIT Medical explains it, a false positive is a “ test result that is wrong, because it indicates the person is infected when they really are not or that they have antibodies when they really don’t.” 

The PCR test used by MIT, like other PCR tests, is very unlikely to return a false positive, MIT believes. 

“If the test comes back positive, we can be sure that it has correctly detected genetic material from SARS-CoV-2. But might PCR tests be too good at finding traces of the virus? That’s a question scientists are starting to investigate.”

False Negative: A false-negative test result indicates that a person is not infected when, in reality, they are, or that they don’t have antibodies when they do.

The CDC report says that false negative results on diagnostic tests happen relatively often.

“A negative result should not give you a sense of false security. If you have any symptoms of COVID-19, it is safest to assume you are infected and act accordingly, even if your diagnostic test comes back negative,” MIT warns.

Self-Administered Tests: The FDA has recently approved the first COVID-19 self-testing kit for home use. The test provides results in just 30 minutes. 

The single-use test, made by Lucira Health, has been given emergency use authorization “for home use with self-collected nasal swab samples in individuals age 14 and older who are suspected of COVID-19 by their health care provider,” the FDA said. 

The kit can also be used at hospitals, but in this case, it should be supervised by a medical expert.

Some of the home health test providers for COVID-19 in the US include Everlywell, Abbott BinaxNOW, Vault, Imaware, Nurx, Scanwell Health, and Radish Health.


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