Short review on Saliva PCR Tests
Short review on Saliva PCR Tests
Saliva PCR testing diagnostic accuracy is similar to nasopharyngeal swab testing
An article on saliva PCR testing was published in “Infection and Drug Resistance” journal by our collective in collaboration with the Department of Laboratory Medicine of Kauno Klinikos and the Department of Infectious Diseases of Lithuanian University of Health Sciences. A good concordance between the NP swab and saliva samples was found. The positive percent agreement was 98.28% (CI 90.76– 99.96%) and negative percent agreement was 98.11% (CI 89.93– 99.95%).
In addition to our results, meta-analyses of SARS-CoV-2 RNA detection with different specimen types have shown that sensitivity and specificity of saliva PCR tests are similar to nasopharyngeal swab tests and no significant difference was found (Nasiri K, Dimitrova A, 2021; Butler-Laporte G et al., 2021). Accordingly, the use of saliva specimen is preferable as no close contact to heathcare personnel is necessary (Nasiri K, Dimitrova A, 2021; Beyene GT et al., 2021). Another benefit of saliva PCR test is that it is more appropriate for testing of children and quarantined individuals (Butler-Laporte G et al., 2021).
Saliva PCR testing is applicable for the detection of asymptomatic and pre-symptomatic infection
A study published in Nature Medicine journal confirms that SARS-CoV-2 virus is detected in the epithelial cells of oral cavity and salivary glands. It was shown that saliva contains infectious virus even if individuals themselves are asymptomatic (Huang N et al., 2021). Feasibility of saliva for testing asymptomatic subjects is supported by another study of a large cohort of workers in Singapore. In the study three types of samples were compared: saliva, nasopharyngeal swabs and nasal swabs. It was found that sensitivity of saliva PCR testing is of a similar or higher level than sensitivity of NP and nasal swabs PCR testing (Teo AKJ et al., 2021).
Saliva PCR testing is superior for children testing
It is often the case that parents oppose nasopharyngeal swab testing of their children as the procedure of sample collection is invasive and uncomfortable. Taking this into consideration, saliva testing was chosen as a simple and uninvasive alternative in Zurich, Switzerland. After testing 170 children a good concordance between saliva and NP swab samples was observed: the positive percent agreement was 93.3% (78.0–99.2%) and the negative percent agreement was 96.4% (91.9–98.8%). As a result, mass PCR testing from saliva samples was launched in Zurich schools (Huber M et al., 2021).
Butler-Laporte G et al. Comparison of Saliva and Nasopharyngeal Swab Nucleic Acid Amplification Testing for Detection of SARS-CoV-2: A Systematic Review and Meta-analysis. JAMA Intern Med. 2021 Mar 1;181(3):353-360. doi: 10.1001/jamainternmed.2020.8876. Erratum in: doi: 10.1001/jamainternmed.2021.0245. PMID: 33449069; PMCID: PMC7811189.
Teo AKJ et al. Saliva is more sensitive than nasopharyngeal or nasal swabs for diagnosis of asymptomatic and mild COVID-19 infection. Sci Rep. 2021 Feb 4;11(1):3134. doi: 10.1038/s41598-021-82787-z. PMID: 33542443; PMCID: PMC7862309.
Nasiri K, Dimitrova A. Comparing saliva and nasopharyngeal swab specimens in the detection of COVID-19: A systematic review and meta-analysis. J Dent Sci. 2021 Jan 29. doi: 10.1016/j.jds.2021.01.010. Epub ahead of print. PMID: 33558826; PMCID: PMC7846225.
Beyene GT et al. Saliva is superior over nasopharyngeal swab for detecting SARS-CoV2 in COVID-19 patients. Sci Rep. 2021; 11: 22640. doi: 10.1038/s41598-021-02097-2. PMID: 34811429; PMCID: PMC8608806.