ABSTRACT
Background@#Nasopharyngeal swab/oropharyngeal swab (NPS/OPS) qRT-PCR is the gold standard for detecting SARS-CoV-2. However, it has its own limitations including cost and invasiveness. As an alternative, individual qRT-PCR testing of saliva samples was validated and shown to be comparable in sensitivity and specificity with NP-OP qRT-PCR. To further maximize its utility, the researchers wish to explore antigen and pooled testing methods.@*Objective@#The study aimed to evaluate the diagnostic accuracy of detecting SARS-CoV-2 infection using saliva-based pooled qRT-PCR and rapid antigen test compared with individual saliva qRT-PCR.@*Methodology@#In this retrospective cross-sectional study, saliva specimen from individuals aged 18 years old and above from the outpatient specimen collection station at the Philippine Children’s Medical Center were tested individually using qRT-PCR (Mag-bind RNA Extraction Kit/MACURA, Allsheng Extraction Machine, Sansure PCR kit, and MA-600 Sansure Biotech). Non-probability convenience sampling was utilized. Based on the individual results, pools of five (5) individual specimens, which includes one (1) positive sample were tested with qRT-PCR for sensitivity. DNK-2150-1S Dynamiker SARS-CoV-2 Ag Rapid Test (Dynamiker Biotechnology Co., Ltd., Tianjin, China) was also used to test individual saliva specimens. . Out of 196 individual saliva specimens, 73 were detected to have SARS-COV-2 by qRT-PCR, while the remaining 123 were negative. Compared with the individual saliva qRT-PCR, rapid antigen tests done showed sensitivity of 46.58% (95% CI 35.13%, 58.02%), specificity of 86.18% (95% CI 80.08%, 92.28%), positive and negative predictive value of 66.67% (95% CI 53.71%, 79.60%) and 73.10% (95% CI 65.89%, 80.32%) respectively. Based on the results of individual saliva-based qRT-PCR, 62 pools were tested and showed sensitivity of 98.39% (95% CI 91.34%, 99.96%). @*Conclusion and Recommendation@#Pooled saliva-based testing for SARS-CoV-2 is comparable with individual saliva-based rapid antigen testing. The use of rapid antigen testing is less sensitive and less specific compared with qRT-PCR consistent with prior reports. Additional studies are recommended to determine optimal conditions for testing.
Subject(s)
SARS-CoV-2 , COVID-19ABSTRACT
Background@#The availability of reverse transcription-polymerase chain reaction (RT-PCR) in detecting severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is limited by the scarcity of resources prompting the use of pooling strategies. Evaluated in this study is the Philippine Children’s Medical Center’s (PCMC) experience in pooled testing done in asymptomatic population.@*Objectives@#Review the pooled SARS-CoV-2 RT-PCR results and case investigation forms (CIF) in asymptomatic population. Determine the incidence of SARS-CoV-2 in asymptomatic population and compare all the individual and pooled tests results. Determine the number of saved test kits and identify clustering in the community.@*Methodology@#This is a retrospective study that reviewed the pooled and individual SARS-CoV-2 RT-PCR results using Allsheng Auto-Pure 32a extraction kit, Sansure Biotech PCR machine and Maccura Sars-CoV-2 test kits. The pooling protocol used by the institution followed the recommendation by Lo et al in the study entitled “An Evaluation of Pooling Strategies for RT-qPCR testing for SARS-CoV-2 infection.”@*Results@#There are 1828 samples which resulted to 165 negative, 68 indeterminate, and 137 positive pools. There are 157, 135, and 68 pools containing 5 individual samples that were classified as negative, positive and indeterminate pools, respectively. Additionally, the negative pools contained 8 pools with 3 individual samples and the positive pools contained 2 pools with 2 individual samples. Deconvolution of the positive and indeterminate pools resulted to 227 and 74 positive individuals, respectively. In this review, the laboratory saved 24% of the test kits and shorten the overall turnaround time by 23 hours.@*Conclusions and Recommendations@#The incidence of SARS-CoV-2 in the population is higher compared to the prevalence of infection in the country. Pooled testing conserved test kits and congruence of pooled and individual ORF Ct-values was observed. An in-depth study including other genes is recommended and assessment of pooling in other population may be pursued.