COVID-19: Detection Of Silent Carriers By Saliva Testing
At Hokkaido University, Japan, scientists have shown an effective testing approach using saliva samples to identify covid-19 infected persons who have not shown any symptoms yet.
Takanori Teshima, a researcher at Hokkaido University says, “Rapid detection of asymptomatic infected individuals will be critical for preventing covid-19 outbreaks in communities and hospitals.”
Testing and tracing have become very crucial to cope with rising covid-19 infected numbers so that isolation can be done as soon as possible. For mass screening, a rapid but effective method is required to take action before virus spreads to a healthy community.
Teshima and other researchers tested and compared nasopharyngeal swabs and saliva of about 2000 people in Japan who showed no symptoms of covid-19. Both PCR test and RT-LAMP test were performed on the samples. The number of positive and negative results was similar in all the samples. The nasopharyngeal swabs and saliva samples were able to detect 77-93% and 83-97% of subjects respectively. Both of these tests were also able to identify infected without infection in more than 99.9% of subjects. The viral loads in nasopharyngeal swabs and saliva samples were equivalent and highly correlated. Teshima says, “Sensitivity of PCR is much higher than previous information that came from initial symptomatic patients data i.e. of about 70%.
This saliva testing carries a volume of advantages as it can easily be self-collected without pain and close contact with health workers can be avoided. This testing can overcome the common practice of nasopharyngeal swab testing. Teshima adds, “ We also discovered that it is not true that sensitivity of RT-LAMP is significantly less than that of PCR test. Moreover, it might be a reliable alternative to diagnose covid-19 infection especially where the diagnosis is required at the place of sample collection such as airport, sports venue and so on,”
The researchers reached the conclusion that self-collected saliva and RT-LAMP testing can provide easy, quick, non-invasive, and accurate results for mass screening with reduced risks of viral transmission to health workers, based upon the research that showed good indication.