Is saliva-based Covid test more accurate to trace Omicron? Here’s what scientists say

Since the onset of the Coronavirus pandemic, the most reliable way to diagnose coronavirus infection has been the swab test which includes probing your nose. Explaining the approach of the health experts, Dr Donald Milton, who is an expert on respiratory viruses at the University of Maryland, told news agency Reuters that testing the nose has been the traditional approach when it comes to diagnosing respiratory infections.

However, the questions over the accuracy of the at-home tests that also rely on the nose test have led experts to debate whether the best way to detect the virus is through the nose. A section of health experts have said that the fool-proof way to test the presence of viruses is through the mouth. Milton said that the virus has a tendency to first show up in the mouth and throat and there is a fundamental problem in the testing approach being adopted during the Coronavirus pandemic.

A few research and studies have also suggested that testing the mouth could help identify the presence of virus days earlier than the time period in which the virus manifests in the nasal swab. However, the saliva testing approach has challenges of its own as along with medical limitations, there are infrastructural gaps as well as most of the testing laboratories are not equipped to process saliva.

Why testing saliva could be helpful

At the very beginning of the pandemic, health experts and scientists had thought of the possibility of conducting Covid-19 tests using saliva. The scientists were looking for an alternative to the deep swab nose test that made people hesitant and fearful of getting tested. The scientists were initially skeptical of the utility of saliva for testing, but by the end of 2020, a number of studies had pointed out that saliva testing was a suitable and accurate method to test the presence of the virus.

Glen Hansen who is associated with the clinical microbiology and molecular diagnostics laboratory at Hennepin County Medical Center in Minnesota told Reuters that there has emerged evidence that points out that saliva, if not better, is as good as the nose swab when it is collected and processed properly. The studies also pointed out that the virus manifested itself a couple of days before in the saliva in comparison to nasal swab.

A recent research of which Milton and his colleagues were a part of found that the presence of virus in the saliva was detected as early as three days before the onset of symptoms and testing the saliva was 12 times more likely to give a positive result than the nasal swab based test. The study is yet to be published in a scientific journal, Reuters reported. The Food and Drug Administration has also authorised a number of saliva-based PCR tests in the last few months which have come to the aid in testing school kids in the United States.

Health experts, more importantly, have pointed out that the saliva-based testing can prove to be particularly beneficial in detecting the virus caused by the Omicron variant which is known to replicate very quickly in the upper respiratory tract. Research in South Africa has also found that while nasal swab based tests were more reliable with the Delta variant, the saliva-based testing can prove more helpful in case of the Omicron variant.

However, before the governments take decisive steps in adopting the saliva-based testing infrastructure, it is important for the scientists’ community to provide conclusive evidence to prove that saliva-based testing is more helpful in containing the spread of the pandemic.