Yale researchers have created a kit that does away with a distinct step or equipment to extract the virus RNA.
Saliva tests: Earlier this month, an alternative form of COVID-19 diagnostic testing was approved by the US’ Food and Drug Administration (FDA). This testing method processes saliva samples and the FDA termed it as ground-breaking, according to a report by IE. The emergency-use approval was given to SalivaDirect, the diagnostic kit prepared by Yale School of Public Health. The report quoted FDA as saying that this was the fifth test that was approved by the US FDA that used saliva samples for testing. But how does a saliva test work?
Similar to RT-PCR, saliva test is also used to detect the presence of the coronavirus. The report stated that in order to do that, the test converts the RNA of the virus into DNA, and then amplifies the DNA. However, the Yale researchers have created a kit that does away with a distinct step or equipment to extract the virus RNA.
The report quoted Yale study as saying that their approach could be implemented on a broader scale, since it did not require saliva collection tubes containing preservatives. Their test also did not require any equipment for the extraction of nucleic acids or specialised reagents.
The kit developed by Yale was initially tested on a group of National Basketball Association’s players and some of its support staff. It has been validated as a test for asymptomatic individuals.
The test that is widely being conducted presently uses nasal and throat samples collected with the help of swabs, which are inserted into the individual’s nose and throat. As compared to this, the saliva test is not invasive. The swab sample collection requires trained healthcare professionals to collect the samples, which puts the healthcare workers at a risk, and increases the requirement for PPE kits as well. On the other hand, a saliva sample does not require a medical professional to intervene, thereby making it safer for healthcare staff and also reducing the usage of PPE kits by nearly 90%, according to the IE report.
SalivaDirect also does not need saliva collection tubes to contain preservatives. It also does not require specialised reagents or any special equipment.
However, the report stated that the test also has its limitations. First, a negative test would not necessarily preclude a SARS-CoV-2 infection and it would have to be complemented by other procedures and observations. Moreover, sometimes saliva samples might contain mucus or blood, and that might make it difficult to pipet.