As early as October last year, the Philippine Red Cross (PRC) has eyed the adoption of saliva testing as a “faster and cheaper” alternative in tracing COVID-19. Now, PRC has gotten the green light from the DOH to start saliva testing and has officially begun operations last January 25.
Before we compare saliva testing to the previous procedure of nasal swab testing, let’s first understand how it’s carried out.
As advertised, saliva testing looks as simple as it sounds: a person merely needs to spit into a sterile 1-milliliter vial, then it’s sealed and prepared for processing. Individuals undergoing the test are instructed not to ingest or consume anything 30 minutes prior to the procedure. Processing the result takes three to four hours, which is a lot faster than swab tests, which often take a full day to see results.
As of writing, the published price of coronavirus saliva testing through the PRC is at P2,000 per test. This is at least P1,800 cheaper than nasal swab testing done by the same organization.
The test can afford to post a lower price since it solicits less effort and it does not require finite chemical reagents.
Ask anyone and they’ll tell you that spitting into a tube is much more preferable than getting either your throat or nasal cavity invaded by a long cotton swab.
The procedure is also perceived as a safer substitute for swabbing because not only do you spend less time inside the facility, you can also collect the drool yourself and avoid contact with any health personnel.
In the US, the Food and Drug Administration (FDA) issued an emergency use authorization to Rutgers University to conduct tests and begin administering spit kits to consumers, enabling them to do the procedure from the safety of their homes and mailing the sample to the laboratory. If such a service is made available here, then saliva testing may be that much more secure.
It’s just as accurate
It may not post better results than the usual nasopharyngeal swab testing, but it yields just as accurate results, and that’s enough.
According to a report by Rappler, the two are equally effective since they both undergo the RT-PCR technique, which is the benchmark for COVID-19 testing.
Paulyn Ubial, PRC’s biomolecular laboratories chief, shared that their initial saliva testing yielded a 98.11% accuracy compared with the saliva pilot test of the University of Illinois which yielded a 99.99 % accuracy. The discrepancy, according to Ubial, could be attributed to differences in sample sizes, since the university tested 1.1 million individuals, while PRC only tested 1,080 saliva samples.
In a study led by epidemiologist Anne Wyllie from Yale University’s New Haven Hospital, she found that “saliva samples often contained more copies of SARS-CoV-2 than did swab samples, and a higher percentage of saliva samples were positive up to 10 days after the initial diagnosis.” To wit, after conducting tests among 495 healthcare workers, “saliva tests identified two more asymptomatic cases than swabs did.”
Sure, it isn’t as widespread of an option as we would have liked, but we still welcome saliva testing as a more effective and less invasive way of detecting coronavirus. The hope now is that more facilities get to carry out this new method, if not completely allowing individuals to take the test at home.