The United States Food and Drug Administration (FDA) has recently given the green light for the emergency use of a novel saliva-based laboratory diagnostic test for Covid-19, named ‘SalivaDirect’. Instead of the traditional nasopharyngeal swabbing method, this test uses saliva samples, making it quicker, more affordable, and minimally invasive.
Introducing SalivaDirect
Developed as an alternative to nasopharyngeal swabbing, SalivaDirect is a newly introduced rapid diagnostic test for detecting coronavirus infection. Nasopharyngeal swabs, often used in Polymerase Chain Reaction (PCR) and antigen tests, are typically employed to identify upper respiratory tract infections like whooping cough and Covid-19 by collecting secretions from the back of the nose and throat. SalivaDirect presents a less invasive and simpler approach.
The Testing Process
The process of collecting and testing saliva samples involves three steps. Firstly, saliva is collected without preservative buffers. Next, it is treated with proteinase K and subjected to a heat inactivation step to eliminate contamination. Finally, it is used directly in the dualplex RT-qPCR mechanism. This is a Quantitative Reverse Transcription Polymerase Chain Reaction mechanism where the viral RNA is quantified to identify the presence of novel coronavirus.
The Science Behind SalivaDirect
Coronaviruses are composed of Ribonucleic Acid (RNA). The RT-qPCR mechanism in SalivaDirect tests is designed to quantify this viral RNA to detect the presence of the virus. Secretions from traditional nasopharyngeal swabs are typically sent to a laboratory where they are grown to make it easier to identify which viruses, bacteria or fungi are present. With SalivaDirect, the need for this process is eliminated.
The Benefits of SalivaDirect
SalivaDirect boasts an impressive sensitivity of about 93%. This means it can detect the virus when the number of copies present in the saliva sample is as low as 6-12 copies per microliter. As the samples are collected from saliva, not nasal specimens, the test is non-invasive, making it more comfortable for individuals.
A major advantage of SalivaDirect is that it significantly reduces the risk of healthcare workers being exposed to the virus. Traditional nasopharyngeal sampling can often cause irritation, sneezing, and coughing, putting healthcare professionals at risk. With saliva sampling, this potential hazard is avoided.
Large-Scale Testing with SalivaDirect
SalivaDirect holds promise for enabling large-scale SARS-CoV-2 testing. As saliva samples prove to be a viable alternative to nasal swabs, it opens up the possibility for at-home, self-administered sample collection. This will result in more accurate testing on a larger scale. Furthermore, because nasopharyngeal swabbing can be uncomfortable for many people, it may discourage them from getting tested. The convenience and comfort of the saliva test are likely to promote testing compliance, facilitating the global fight against Covid-19.
The source of this content is TH.