Fri 3 Jul 2020
More convenience is important when mass testing
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The current testing blitz in Victoria will be using saliva samples from residents of infection hotspots. The main reason for this is that saliva samples are much easier to collect than nasopharyngeal swabs and also safer for the person carrying out the sampling. The collector only has to give the person being tested a specimen jar and ask them to collect a few millilitres of saliva in their mouths and then spit it into the container.
A number of studies have been done in countries around the world comparing saliva sample testing with nasopharyngeal swabs, oropharyngeal swabs and sputum. Sputum is different from saliva. Saliva is the watery liquid that collects in our mouths. Sputum is material that has been coughed up from deeper in our airways.
Most studies including one from the Doherty Institute in Melbourne have found that saliva is about 80 – 90% as effective in picking up COVID-19 infections as nasopharyngeal swabs which are the current standard sample. When trying to test very large numbers of people such as in the current testing in Melbourne, the convenience and safety of saliva sampling outweighs to small loss of sensitivity in disease detection.
Doherty Institute report
European Centre for Disease Control and Prevention report