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COVID-19 ISO Insights

How Effective Are Covid-19 Nasal Swabs?

December 13, 2021

By Travis Decaminada

Key Takeaway: Getting tested for Covid-19 has become a routine part of many people’s lives, and said tests generally involve a nasal swab. There are three different types of nasal swab tests, with more invasive tests reportedly being more accurate. Complicating the matter, countries and institutions around the world appear to be having difficulty agreeing on which best practices to promote when it comes to nasal swabs.

Most people are likely aware of Covid-19 tests involving nasal swabs. To some, these tests are merely an inconvenience, whereas others insist that the tests can cause everything from nosebleeds to headaches. Regardless, since the start of the pandemic millions of noses have been swabbed, reports the New York Times, but are some swabbing kits or methods better than others?

Techniques for swabbing vary by geography. Reportedly, in some areas of the U.S. healthcare workers will allow patients to swab their noses themselves, whereas in other countries, such as South Africa, practitioners are more likely to swab areas deep within a patient’s throat. From the article:

The range of swabbing raises questions: Who is doing it right? How deeply should the swab slide into your nostril? How long should it spend up there? Does an accurate test have to be uncomfortable? Unfairly or not, some countries have reputations for brutal tests.

Several different governments and health agencies from around the world have released guides detailing best practices, but oftentimes these directives disagree with each other. Some guides suggest that swabs only be inserted a few centimeters into a patient’s nostril, whereas others assert that a swab should be inserted until it meets resistance. China has even made anal swabs a requirement for some foreign visitors. Ultimately, all these tests are trying to do is collect evidence of the presence of Covid-19.

The Nasopharynx

At the very back of a person’s nasal cavity lies their nasopharynx, which plays an important role in breathing, but is also a site where the Covid-19 virus actively replicates. Unsurprisingly, many testing methods involve swabbing a person’s nasopharynx. When conducting a swab test practitioners must be precise to avoid hitting sensitive areas around the nasopharynx (bone in particular) - administered at the wrong angle or too deeply these tests can lead to pain or discomfort.

Three Different Swabs

According to the New York Times, there are three widely used Covid-19 nasal swab tests:

  • Nasopharyngeal – This test aims to swab the deepest areas of the nasal cavity, specifically the nasopharynx.
  • Mid-Turbinate – A middle ground between the three tests, mid-turbinate tests swab areas in the middle of the nasal cavity.
  • Anterior Nares – The least invasive test, generally involves only swabbing the shallow areas of the nose.

Nasopharyngeal tests were widely administered during the beginning of the pandemic due to the tests known ability to detect both SARS and influenza, and although opinions are still forming, most experts agree that this test is still the most accurate diagnostic available. Allegedly, nasopharyngeal tests are about 98% accurate at detecting Covid-19 whereas mid-turbinate and anterior nares tests only have an accuracy range of between 82-88%. A noticeable difference.

Of interest, several different countries are currently working on developing robots that could theoretically test for Covid-19 more effectively than a human practitioner.

See also:

Information about Covid-19 tests from the Centers for Disease Control and Prevention (CDC)

Information about Covid-19 tests from the World Health Organization (WHO)

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