Covid-19 Testing: Nose or Throat?
The surge in Covid-19 infections caused by the Omicron variant has placed a noticeable strain on testing sites. The result is that more people are opting to go for at-home testing options such as the Healgen tests.
In the UK, the previously provided free government tests are no longer available for most people. However, people can still access paid PCR or lateral flow tests (LFT) from pharmacies and online shops.
Some lateral flow tests available in the UK can be used with both nasal and throat swabs. Most are nose only. One of the common questions we get from our clients is why some lateral flow tests are nose-only while others require users to take a swab from both the nose and the throat.
Well, there is reason to believe that tests from the two parts of the body can yield different results. This has a lot to do with the changing understanding of the Covid-19 virus, especially the most current Omicron variant. While past versions of the Covid-19 virus settled in the lungs, the Omicron variant, according to past studies, starts in the throat and later moves to the nasal cavity. What this means is that swabbing the throat of someone who has just been infected with this variant may yield positive results, but a nose swab in the same person will most likely yield negative results.
Also, there have been claims on social media suggesting a throat swab may give more accurate results than the recommended nasal swab for self-testing kits, considering that one of Omicron’s major symptoms is a sore throat.
So, the big question is, do you have to swab a nose or throat for Covid-19?
Well, to shed more light on this issue, let’s look at the nasal vs. throat swab for Covid-19 in detail.
Nose or Throat: What Is Better for Covid-19 Testing
When it comes to testing infectious diseases such as Covid-19, small details like the source of the sample can greatly impact the results. Most of the rapid antigen tests for Covid-19 are designed to collect samples from the nasal cavity. A few others recommend swabbing from both the nasal and throat areas.
A nasal swab collects the bodily fluid from the back of the nostrils and can be generally self-administered at home. On the other hand, throat swabs collect samples from the back of the throat, and in most cases, a medical provider performs this swab.
There is limited research to determine the most accurate method to test for Covid-19. And although evidence suggests that the Omicron variant tends to infect the upper respiratory tract compared to the lower respiratory tract, research is still in progress on whether a throat swab is more likely to detect it than a nasal swab.
In one recent study, the researchers suggest that saliva swabs may give more accurate results than nasal swabs when it comes to the detection of the Omicron variant. However, the study focused on the use of PCR tests which are totally different from at-home rapid tests.
Why Experts Say That Nasal Swabs Give the Most Accurate Results
When it comes to Covid-19 at-home antigen tests, experts agree that they were designed and validated for use using nasopharyngeal swabs. This means that extensive studies on these tests were done using nasal swabs and not swabs from other parts of the body.
Also, considering that the nasal microenvironment is different from that of the throat, a rapid antigen test such as the FlowFlex Covid test may not produce the same results when using samples from the two body areas. Experts advise that it’s important to use LFTs as authorized and that users should follow the instructions provided on how to obtain the sample needed for testing.
Another concern raised by experts regards the collection of an accurate throat swab. In most cases, healthcare professionals who are familiar with the correct throat swabbing procedure collect these sample types. Self-administering of a throat swab is highly discouraged as the process is more complicated than nose swabbing. Besides, if the right throat swabbing procedure isn’t followed, it will not only lead to false negatives but can also cause harm to the user.
Experts also warn that Covid-19 rapid tests are highly susceptible to changes in pH levels. Unfortunately, the pH or acidity level of the throat is affected by foods and drinks. For instance, school-going children in the UK found out that drinking fruit juice often led to false positive Covid-19 results. The reason is that drinks such as fruit juices, soft drinks, and coffee lowers the pH level of your throat, which can affect a Covid-19 antigen result.
In closing, there has been a lot of advice on social media to swab your throat in addition to your nose when using home Covid-19 tests. However, experts are yet to recommend this. Instead, they advise that if you’re looking for a lateral flow test to order in the UK, it’s best to use it as per the manufacturer’s instructions. And although the new Omicron Covid-19 variant may lead to changes in the testing strategy, users need to use tests as they’re designed until more scientific evidence suggests otherwise.