“Omicron, first detected in the mouth”… Raises the need for nasal swab and saliva testing together


As the mutation of Corona 19 showed a different trend from the existing mutation, the debate over a more effective Corona 19 test method was rekindled.

According to the New York Times on the 14th (local time), the medical community is claiming that the existing test method, which collects a sample by scraping the deep inside of the nose with a cotton swab, is not effective against Omicron mutations.

This is because it is difficult to detect infection quickly enough to prevent further spread by nasal examination because it mainly proliferates above the airways and has a short incubation period.

Dr. Robbie Sica said, “I think the omicron mutation has changed the game for COVID-19 testing. It is because of the speed at which the omicron mutation replicates and spreads.”

Therefore, some experts are arguing that the saliva of the test subject should be used instead, saying that more viruses are detected in the mouth than in the nose in the early stages of COVID-19 infection.

Dr. Donald Milton of the University of Maryland in the US recently published a study result showing that the amount of virus detected in saliva is three times higher than that in the nose for five days from three days before the onset of COVID-19 symptoms.

After that, the amount of virus in the nose is greater than that of saliva.

Therefore, using a patient’s saliva, Dr. Milton argued, could detect the presence of COVID-19 several days earlier than when using a sample collected from the nose.

In fact, in South Africa, there was a research report that showed that the conventional method of collecting a sample by scraping a cotton swab deep inside the nose for the delta mutation was more effective than the saliva test, but the opposite result was found for the omicron mutation. .

However, the COVID-19 test using saliva also has disadvantages.

When trying to diagnose an infection at an early stage with a relatively small amount of virus, the possibility of errors is relatively high, and it can be easily contaminated with food than the inside of the nose, and it is difficult to apply to dehydrated patients.

“It’s a more uncontrolled environment compared to the nasal passages,” said Joseph Drissy, a biochemist at the University of California who served as chairman of the Chan Zuckerberg Biohub. said.

For this reason, self-diagnosis kits that test both nasal samples and saliva in the mouth are emerging in the UK and other countries.

Experts predicted that in the long term, various methods of testing will be established and the COVID-19 test will change in the direction of a customized test that takes into account the condition or situation of the test subject.

Dr. Marie Hayden, a clinical microbiologist at Rush University Hospital in Chicago, said, “We need to have flexibility in our testing system in response to the future global infectious disease pandemic and the evolution of Omicron.”


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