https://orcid.org/0000-0001-9766-7108
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ABSTRACT
Background
Comparison of clinical value of RT-qPCR-based SARS-CoV-2 tests performed on saliva samples (SSs) and nasopharyngeal swab samples (NPSs) for prediction of the COVID-19 disease severity.
Methods
Three paired SSs and NPSs collected every 3 days from 100 hospitalised COVID-19 patients during 2020 Jul-2021 Jan were tested by RT-qPCR for the original SARS-CoV-2 virus and compared to 150 healthy controls. Cases were divided into mild+moderate (Cohort I, N = 47) and severe disease (Cohort II, N = 53) cohorts and compared.
Results
SARS-CoV-2 was detected in 65% (91/140) vs. 53% (82/156) of NPSs and 49% (68/139) vs. 48% (75/157) of SSs collected from Cohort I and II, respectively, resulting in the total respective detection rates of 58% (173/296) vs. 48% (143/296) (P = 0.017). Ct values of SSs were lower than those of NPSs (mean Ct = 28.01 vs. 30.07, P = 0.002). Although Ct values of the first SSs were significantly lower in Cohort I than in Cohort II (P = 0.04), it became negative earlier (mean 11.7 vs. 14.8 days, P = 0.005). Multivariate Cox proportional hazards regression analysis showed that Ct value ≤30 from SSs was the independent predictor for severe COVID-19 (HR = 10.06, 95% CI: 1.84–55.14, P = 0.008).
Conclusion
Salivary RT-qPCR testing is suitable for SARS-CoV-2 infection control, while simple measurement of Ct values can assist in prediction of COVID-19 severity.
Acknowledgments
The authors would like to acknowledge Jonas Belevicius, Vaida Kurmauskaite, and Ieva Asmenaviciute for laboratory testing.
Disclosure statement
Mantvydas Lopeta and Julius Gagilas are employees at JSC Diagnolita. JSC Diagnolita has developed the kits used in this research. The authors declare no other conflicts of interest.
Author contributions
KS and BZ performed data analysis and drafted the manuscript. BZ, RS, KZ, EM, TS, MP, and JG participated in sample collection and handled the clinical data. KS, BZ, RZ, and ML performed statistical analysis. JG, AP, LJ, and SJ carried out the study design. All authors read and approved the final version of the manuscript.