Filenews 18 August 2020
Researchers from Yale University in the US developed a program called SalivaDirect that relies on saliva testing instead of a nasopharyngeal smear.
A huge role in monitoring the transmission of coronavirus is considered to be the regular control of large numbers of people. The rapid detection and isolation of active cases – i.e. individuals who can transmit the virus, whether symptomatic or asymptomatic – is a key tool for limiting the spread of the disease.
In addition, as experts point out, accurate data on the number of active cases are required for health policy-making and similar measures (at local, and wider e.g. prefectural, regional or national level).
Regular check-up is also important to inform each individual what the short-term risk of transmission is and how safe it is to return to work, school, etc.
Many obstacles to increasing the number of tests
However, the increase in the number of tests for effective surveillance of SARS-CoV-2 encounters many obstacles.
One of these is the need to take nasopharyngeal smears that can be unpleasant, which discourages people from being tested frequently.
Smears must also be collected by someone trained to do so, adding another logistical barrier and endangering exposure to those performing the download.
In addition, the rapid global spread of SARS-CoV-2 has caused huge problems in supply chains that provide materials for molecular tests, including masks for obtaining coatings and necessary reagents.
Molecular test with saliva test
Researchers from Yale University in the US have tried to overcome some of these obstacles by developing a program called SalivaDirect, and relying on saliva testing instead of a nasopharyngeal smear.
While it is still based on a similar molecular process to previous tests (called RT-qPCR), it is simpler to reduce the cost and need for reagents.
The Professors of the Therapeutic Clinic of the Medical School of the National and Kapodistrian University of Athens, Efstathios Kastritis and Thanos Dimopoulos (Rector of ekpa), summarize the data on this program. First of all, the molecular test is done from a saliva sample and not from a nasopharyngeal smear.
In addition to easier collection of the sample, the researchers found that expensive preservatives are not required for saliva tests, which reduces costs. The researchers also tried and succeeded in bypassing the process of extracting nucleic acid from the samples before the test.
The extraction of nucleic acid is time consuming and costly and there have been global shortages of consumables needed to be made. So, for SalivaDirect, they have managed to skip this step, making the test accessible to more labs.
The test is flexible as different variants of equipment can be used in different laboratories and reagents, so that more laboratories can do molecular tests and prevent deficiencies in specific reagents only.
SalivaDirect received "rapid" authorisation (it is an initial approval only) from the FDA on 15 August in order to further develop it. it could be an excellent tool that laboratories can use for quick examination of many people, while to a significant extent it addresses the problem of the adequacy of consumables.
But additional improvements and additional testing are needed.
Efforts are also directed at increasing the number of people who can be tested per day.
Automation of the process is also necessary and researchers are working with various institutions to develop validation of robotic systems for the processing of samples and/or PCR.
Most available tests for SARS-CoV-2 have not been validated for the detection of asymptomatic infections, which is the primary objective of a large-scale screening and population monitoring program. SalivaDirect will need to be compared with conventional methods of detecting such cases. Researchers have their research available on the pre-publication platform medrxiv.org.
Source: in.gr
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