According to a study published in the journal Clinical Infectious Diseases , testing saliva samples are effective in detecting asymptomatic Covid-19 cases .

For the study, the researchers tested and compared the nasopharyngeal swabs and saliva samples of around 2,000 people in Japan who did not demonstrate Covid-19 symptoms.

Takanori Teshima from Hokkaido University in Japan said in the study: “Rapid detection of asymptomatic infected individuals will be critical for preventing Covid-19 outbreaks within communities and hospitals.”


Researchers carried out two virus amplification tests on the collected samples for study: the widely available PCR (polymerase chain reaction) test, and the less commonly used RT-LAMP test.

Also read: Saliva swab test better in detecting Covid-19 than nasal swab test: Study

Both the tests yielded almost the same number of positive and negative outcomes, with the nasopharyngeal swabs and saliva samples able to detect those with the infection in 77-93 per cent and 83-97 per cent of subjects, respectively.

The virus loads detected in nasopharyngeal swab and saliva were equivalent and highly correlated, they said.

“PCR sensitivity is much higher than previously thought 70 per cent that came from initial data of symptomatic patients,” Teshima said.

Teshima believes that saliva testing has significant logistic advantages over the commonly used nasopharyngeal swab testing.

“Self-collection of saliva is painless for examinees and, more importantly, it eliminates the close contact with the examiners, reducing the risk of viral exposure,” said Teshima.

Teshima mentioned it is unlikely that the sensitivity of RT-LAMP is significantly less than that of the PCR test.

This suggested that it might be a useful alternative for diagnosing Covid-19 infection, especially where the diagnosis is required at the point of sample collection, like in sports venues or at airports.

Researchers claimed that rapid RT-LAMP testing could provide easy, non-invasive, quick, and relatively accurate results, with minimal risk of viral transmission to healthcare workers.