Since March 11, 2020, the start of the current pandemic, there have been more than twenty-seven million cases of COVID-19 in the world and almost 900,000 deaths. More than six million of these cases have been in the United States (CDC 2020). A recent study, conducted by scholars in the Journal of Clinical Microbiology, investigated two different methods of COVID-19 testing. They found that the saliva test method is overall a better method than the nasopharyngeal (NPS) test method. These findings are significant because people are dying of this disease, and the testing method needs to be improved to save lives.
An article from the Journal of Clinical Microbiology described an investigation in Melbourne, Australia that tested a pool of patients using the NPS test method and the saliva test method. Eloise Williams, Katherine Bond, Bowen Zhang, Mark Putland, and Deborah Williamson conducted this study, and they all work at the Royal Melbourne Hospital in the department of microbiology. This investigation determined the adequacy, viability, and suitability of the saliva test. The authors explain the benefits, “The use of saliva has several advantages compared to collection of NPS…Further, saliva collection does not require specialized consumables, causes less patient discomfort, and may be a useful sample for self-collection” (Williams et al. 2020, 1). Other virus strains have been found in patients about one month after they are infected, which means that saliva is possibly more advantageous for detecting coronavirus (Sri Santosh et al. 2020).
In the span of eight days, 622 patients were tested for COVID-19 at a screening clinic in Australia. Every patient was tested with the NPS test, and 522 patients were tested with the saliva test. Patients collected saliva in their mouth for 1 to 2 minutes and spit one to two mL of saliva into a container. The specimens were brought to the lab and an Amies medium containing charcoal was added to prolong life of the pathogens. Amies is used for the transportation of specimens to the laboratory. They used the Amies medium instead of the vital transport medium (VTM) to conserve the VTM. The time it took to get the medium in the sample collection ranged from 55 to 537 minutes. RNA, which is ribonucleic acid, converts DNA information into proteins and is extracted from the NPS and saliva samples. Finally, the samples underwent reverse transcriptase testing to find if it was positive or negative. The findings were that the saliva test is more efficient and practical than the nasopharyngeal test.
COVID-19 developed into a pandemic in March. However, there is prior research on nucleic acid extraction kits and the diagnosis of coronavirus. Another article written in August of 2020 describes the pros and cons of each method of testing (Wang et al. 2020). The authors explain that the advantage of saliva sampling is a lower risk of healthcare infections. A disadvantage of this method is that there are limited tools available (Wang et al. 2020). This study responds to the debate over whether saliva tests are better than the NPS tests. The NPS tests are more widely known and used, but with the continuation and spread of the virus, research and studies expand.
The authors admitted that they designed their investigation with ambulatory patients, meaning that they are not bedridden. Normally when studying COVID-19, testing is conducted on inpatients who stay in the hospital during treatment. They also point out that saliva is highly sensitive in diagnosing COVID-19. Often times in studies, the situations are simulated, making it dangerous to generalize results to the world. However, this study uses real people and real testing for COVID-19, so the results should be accurate. Another limitation noted throughout researching this topic is the lack of information and knowledge on the topic due to the recency of the new strand of the virus.
This information is important because if a patient receives the SalivaDirect test, results can be delivered in almost one day. The saliva test also saves swabs and other reagents needed. It is significant because the saliva test means less risk for health care workers because a patient can administer the test in the privacy of his own home. Most importantly, the saliva test saves money for personal protective equipment and also the time of many health care workers.
Julia Strait published a recent article from the Washington University School of Medicine on August 28, 2020. Strait provides helpful information about a new saliva test (different from SalivaDirect) that could benefit the city of St. Louis and the state of Michigan as schools and businesses start to reopen. This new test is anticipated to detect the virus before patients even have symptoms as well as asymptomatic patients (Strait 2020).
Getting tested for Coronavirus has become a frequent necessity for many people, and it should be comfortable, easy, and fast. Timely testing results have never before been more imperative concerning one’s ability to attend school, work, and thrive in a community. This information could be applied to a potential future pandemic informing scientists and doctors with the knowledge that saliva tests are more efficient and cheaper for this type of virus.
References
CDC. 2020 Mar 28. Coronavirus Disease 2019 (COVID-19) in the U.S. Centers for Disease Control and Prevention. [accessed 2020 Sep 8]. https://www.cdc.gov/covid-data-tracker.
Strait, Julia. COVID-19 saliva test enables screening on a massive scale. [accessed 2020 Aug 31]. https://medicalxpress.com/news/2020-08-covid-salivatest-enables-screening-massive.html.
Wang Y, Lee Y, Yang T, Sun J, Shen C, Cheng C. 2020 Aug 13. Current diagnostic tools for coronaviruses–From laboratory diagnosis to POC diagnosis for COVID‐19. Bioeng Transl Med. doi:10.1002/btm2.10177. [accessed 2020 Sep 1]. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7435577/.
Williams E, Bond K, Zhang B, Putland M, Williamson DA. 2020. Saliva as a noninvasive specimen for detection of SARS-CoV-2. J Clin Microbiol. 58(8). doi:10.1128/JCM.00776-20. [accessed 2020 Aug 26]. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7383524/.
Featured Image Source:
Britannica ImageQuest. [accessed 2020 Sep 8].
https://quest.eb.com/search/300_2259730/1/300_2259730/cite
For Further Reading
Caly L, Druce J, Roberts J, Bond K, Tran T, Kostecki R, Yoga Y, Naughton W, Taiaroa G, Seemann T, et al. 2020. Isolation and rapid sharing of the 2019 novel coronavirus (SARS-CoV-2) from the first patient diagnosed with COVID-19 in Australia. Medical Journal of Australia. 212(10):459–462. doi:10.5694/mja2.50569.
Kim Y, Yun SG, Kim MY, Park K, Cho CH, Yoon SY, Nam MH, Lee CK, Cho Y-J, Lim CS. 2017. Comparison between saliva and nasopharyngeal swab specimens for detection of respiratory viruses by multiplex reverse transcription-PCR. Journal of Clinical Microbiology. 55(1):226–233. doi:10.1128/JCM.01704-16.
Temporal profiles of viral load in posterior oropharyngeal saliva samples and serum antibody responses during infection by SARS-CoV-2: an observational cohort study. 2020. The Lancet Infectious Diseases. 20(5):565–574. doi:10.1016/S1473-3099(20)30196-1.
