ABSTRACT
Background: Almost a year has passed since the start for Covid 19 pandemic, however with no human immunity and no vaccine for prevention early diagnosis remains the mainstay to contain the infection and prevent the spread of the vi- rus. RT-PCR is said to be the most sensitive test currently. However, Truenat is also widely used being approved by ICMR, hence a comparative study of RT-PCR & Truenat was taken up in this study. Methods: A total of 200 samples were taken from patients having signs and symptoms (clinically suspected) of COVID 19. Samples obtained via oropharyngeal and nasopharyngeal swabs were analyzed on both RT-PCR and Truenat. Viral load in samples were evaluated using Ct value of targeted genes by both the techniques. Results: Out of 200 samples, 184 showed similar results via RT-PCR and Truenat i.e., 61 positive and 123 negatives. 16 samples showed discordant results. Out of 16 samples, 5 were positive and 11 were negative by RT -PCR. However, by Truenat 11 were positive and 5 were negative. The Ct values of targeted genes range between 13-30 for E-gene and 16-32 for RdRp gene. Conclusions: The detection of SARS COV-2 patients with mild form of disease (which were persistently negative by RT- PCR) was higher by Truenat. P value being 0.077 which is significant at 90% level of significance. Hence though identifi- cation of viral RNA by RT-PCR is the gold standard, its sensitivity is lower compared to Truenat. Hence, we can suggest that Truenat is a diagnostic method with higher sensitivity, closed system hence lower chances of contamination and at the same time providing faster results at low cost, easy to perform as a point of care test, portable and requiring lower expertise to operate compared to RT-PCR
ABSTRACT
Background:COVID-19 being an airborne High Consequence Infectious Disease (HCID) warrants early detection to con- tain spread especially in a pandemic that has gripped the world by storm. RT-PCR (Real time polymerase chain reaction) is considered the gold standard confirmatory test for COVID-19. The assay is based on detection of viral RNA and genes located in different regions of SARS-COV 2 genome with a potent detection limit of >=10 genomic copies per reaction. Average duration of RT-PCR result becoming negative from positive gives an idea as to how long a patient needs quaran- tine and also a perception of clinical recovery. Methods:This study includes 1766 positive patients tested at JLN Medical College Ajmer, Rajasthan, out of the total pa- tient who underwent RT-PCR testing from 26-08-2020 to 17-11-2020. The samples were collected through oro or naso- pharyngeal swabs. Automated RNA extraction was done using Thermofisher and Perkin Elmer machines and RT -PCR was done on Bio-Rad Machines. Results:Out of 1766 samples, 61 samples in the age group of 0-14 years (children and young adolescents) showed an average duration of 10.5 days and range of 3-18 days to be reported negative, 1537 in the age group of 15-65 years (working age population) had an average duration of 11.3 days and range 1 -32 days, 168 for >=66 years (elderly popula- tion) had an average duration of 10.7 days and range of 1-23 days. When gender is compared, 505 were females with average illness duration of 10.7 days and range 1-32 days and 1261 were males with average duration of 11.2 days and range 1-31 days. Conclusions:Once tested positive there is a very subtle difference in duration of being reported negative between the various age groups and gender with children and young adolescents getting an earlier negative result than others and females earlier than the male population.