Health and Fitness

What difference is between a molecular test and rapid antigen tests for COVID-19?

Rapid antigen testing identifies the virus’s antigens (proteins). Although results are obtained more quickly than with molecular or antibody tests, they are less sensitive, particularly in discovering asymptomatic persons. In addition, they are only capable of detecting active infection during the disease’s early stages.

Molecular assays, such as real-time polymerase chain reaction (PCR), detect the virus’s genetic material, RNA. As a result, they exhibit a greater degree of sensitivity and specificity. In addition, compared to quick antigen tests, they can detect the virus in asymptomatic persons and detect active infection for a longer time.

COVID-19 test accuracy

COVID-19 is a respiratory disease that can cause serious illness, particularly in patients who have prior health disorders such as diabetes, obesity, or hypertension.

Two different types of testing are frequently performed to determine whether a person is currently infected with SARS-CoV-2, the coronavirus that causes COVID-19.

The first sort of test is a polymerase chain reaction (PCR), sometimes referred to as a diagnostic or molecular test. A polymerase chain reaction (PCR) test can aid in the diagnosis of COVID-19 by detecting the coronavirus’s genetic material. The Centers for Disease Control and Prevention (CDC) believe PCR tests to be the gold standard for diagnosis.

The second type is a test for antigens. These assays aid in diagnosing COVID-19 by looking for chemicals on the surface of the SARS-CoV-2 virus.

Rapid tests are COVID-19 tests that offer results in as little as 15 minutes and do not require laboratory processing. They are frequently in the form of antigen testing.

While fast tests can deliver findings quickly, they are not as accurate as PCR tests performed in a laboratory. Continue reading to learn about the accuracy of quick testing and when they should be used in place of PCR tests.

How accurate are COVID-19 fast tests?

Rapid COVID-19 testing frequently offers results within minutes and does not require professional laboratory analysis.

Most fast tests are antigen tests, and the names are frequently used interchangeably. However, the CDC discontinued the term “quick” when referring to antigen tests, as the FDA has approved laboratory-based antigen tests.

Rapid testing, often known as point-of-care tests, can be performed at the following locations:

  • a residence with a residence COVID-19 examination
  • a physician’s office
  • pharmacies
  • clinics in schools
  • facilities for long-term care
  • airports
  • Drive-thru testing locations

You or a medical practitioner will insert a cotton swab into your nose, throat, or both to collect mucus and cells during the test. Typically, your sample is transferred to a strip that changes color if you test positive for COVID-19.

While these tests are quick, they are not as accurate as laboratory testing since they require a higher concentration of virus in your sample to give a positive result. Rapid testing has a significant likelihood of producing a false negative effect.

A false negative result indicates that you do not have COVID-19 when you do.

Molecular Examinations

They look for the virus’s genomic material and are currently the gold standard for diagnosing COVID-19.

Method: Nasal or throat swab and saliva for specific tests.

Turnaround time varies according to the type of test.

Most testing locations employ polymerase chain reaction (PCR) tests, which are highly accurate but require big certified labs and competent lab personnel. It may take several days for results to be returned.

Rapid molecular testing at the point of care, such as Abbott’s ID NOW, can offer results in as little as 13 minutes. Other permitted platforms take between 20 and 120 minutes to complete and are pretty simple. These tests are also applicable outside of traditional health care settings, and they are rapidly gaining popularity.

Accuracy: Some molecular point-of-care assays, notably Abbott ID NOW, are less sensitive than reference laboratory tests. False negatives do occur with molecular tests, although they are uncommon. False negatives are extremely infrequent during the period when a person has the most virus, typically the first five days of symptoms.

Takeaway: If you tested negative for the virus during the first week of exhibiting symptoms, you are most likely not infected. It may be more challenging to determine at a later sickness stage.

Antigen Examinations

What they do: These rapid tests, which look for proteins on the virus’s surface or within, are inexpensive, effective, and quick. FDA-approved for emergency use, including those for use in the home. They can make a clinical diagnosis in patients who present with symptoms within the first five days. However, they are not suggested for screening asymptomatic populations.

Nasal or pharyngeal swab

Turnaround time is as little as 10–15 minutes or 30 minutes.

Accuracy: False-positive findings are uncommon when these tests are utilized, as stated above, but if you have symptoms and receive a negative antigen test result, you may still have COVID-19 and may require confirmation with a molecular test. Although data are more limited in asymptomatic individuals, the test is less accurate.

Takeaway: Antigen testing would be excellent screening tests for early symptomatic individuals, especially in areas where access to molecular tests is limited or results are delayed for an extended period. Screening symptomatic pediatric kids at risk of contracting respiratory viruses may also be a cause to employ them.

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