Diagnostic evaluation of nasopharyngeal swab and saliva kits against SARS-CoV-2: Adequate rapid screening is deemed necessary to overcome COVID-19 Pandemic

Abstract

SARS-CoV-2 is the virus associated with the disease called COVID-19 and become a global pandemic. The only way to prevent its severe scenarios is through timely and rapid testing. In comparison to more time taking gold-standard RT-PCR testing, rapid diagnostic kits are used. For better prevention and diagnosis of SARS-CoV-2, the analysis of rapid diagnostic kits' accuracy and specificity is necessary. This study is meant to assess and examine the viability, responsiveness, and explicitness of quick antigen distinguishing nasopharyngeal swabs (NPS), and saliva-based units. The study was conducted on 200 suspected COVID-19 patients from Islamabad, 100 of which were RT-PCR positive while 100 were RT-PCR negative. For the analysis of Rapid diagnostic COVID-19 kits (RDT), nasopharyngeal swabs (NPS) and saliva samples were taken from the RT-PCR positive and negative patients. Among 100 RT-PCR positive patients, 62% were males (19 - 91 years), 34% were females (20 - 78 years) and 4% were children (6 - 17 years). False-negative results were significantly more observed in saliva-based RDTs of the sample (49%) as compared to nasopharyngeal swab RDT (38%). There were 2% invalid results in saliva-based RDT and 3% invalid results in Nasopharyngeal swab RDT. While among 100 RT-PCR negative patients 69% were males (19 - 80 yrs), 27% were females (18 – 77 yrs) and 4% were children (12 - 16 yrs.). False positive results were significantly more in saliva-based RDT (22%) as compared to Nasopharyngeal swab RDT (13%). The sensitivity and specificity of saliva-based RDT were 67% and 87% respectively while that of Nasopharyngeal swab (NPS) was 72% and 82% respectively, both of which were less than the gold standard RT-PCR sensitivity demanding the introduction of more sensitive RDT kits in Pakistan for accurate detection of COVID-19.