Saliva tests for Covid-19 as accurate as nasal swabs, UAE study finds

The technique could lead to faster and less intrusive screening

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Saliva screening is as effective as nasal swabs when it comes to testing for Covid-19, researchers at a university in the UAE have found.

The study, published the peer-reviewed journal Infection and Drug Resistance, found testing for the virus using saliva is equally as accurate as the widely used PCR tests, which require a more invasive and uncomfortable nasal swab.

The findings could change the way people are screened and increase testing capacity, as a saliva sample could be self-administered without the help of medical staff.

This would also reduce potential exposure of staff to the virus and minimise the amount of medical equipment used.

With everyone looking for easy alternatives, our study shows how the adoption of saliva as specimen for Covid-19 testing can decrease the strain on healthcare resources

A team from Mohammed Bin Rashid University of Medicine and Health Sciences took saliva and nasal swabs from 401 adults who had attended Khawaneej Health Centre for a Covid-19 test. Half of the sample size were asymptomatic.

The samples were tested for detection of Sars-CoV-2, the virus that causes Covid-19, at Unilabs Dubai.

The findings of the study showed that the saliva can be used for viral detection with 70 per cent sensitivity and 95 per cent specificity, proving to be just as effective as the nasal swab.

Studies have suggested that coronavirus initially binds to cells in the body’s nasal cavity and then begins replicating, spreading through the body’s respiratory tract. The virus is understood to then spread to the body’s oral cavity. Previously, it was questioned whether there would be enough virus to be spotted easily with a saliva test. The UAE study, among others, indicates that it is possible.

Patients collected specimens of their own saliva in sterile containers. No preservative was needed while they were being taken to the laboratory.

Covid-19 saliva test

“This study has shown good diagnostic accuracy for saliva and the feasibility for its utilisation as a potential specimen of choice in community settings and population-based screening,” said Prof Abiola Senok, lead investigator of the study and professor of microbiology and infectious diseases at the College of Medicine at MBRU.

Co-author Dr Hanan AlSuwaidi said saliva testing would reduce strain on critical health equipment, eliminate the need for preservatives and be a more cost-efficient method of mass testing.

“With everyone looking for easy alternatives to nasopharyngeal swab, our study shows how the adoption of saliva as specimen for Covid-19 testing can decrease the strain on healthcare resources,” she said.

“For the current nasopharyngeal swab, staff need to wear personal protective equipment when taking the samples from the patients. With saliva the patients collect their own samples, therefore PPE resources can be freed up for use elsewhere.”

The research team from MBRU was joined by teams from Dubai Health Authority, Unilabs, Cleveland Clinic Abu Dhabi; NYU Abu Dhabi and the National Reference Laboratory.

The study was one of the first research projects to receive approval from the Emirates Institutional Review Board for Covid-19 Research.

Several Covid-19 tests are currently available across the UAE.

These include the standard nasal swab PCR test, the Dh50 laser DPI test, which scans the blood for signs the body is fighting a virus, the LamPORE test, designed to test both saliva and swab RNA samples, and a serology test, which scans for Covid-19 antibodies and can tell if someone has had the virus and has any immunity to it.