ABSTRACT
The rapid spread and evolution of various strains of SARS-CoV-2, the virus responsible for COVID-19, continues to challenge the disease controlling measures globally. Alarming concern is, the number of second wave infections surpassed the first wave and the onset of severe symptoms manifesting rapidly. In this scenario, testing of maximum population in less time and minimum cost with existing diagnostic amenities is the only possible way to control the spread of the virus. The previously described RNA extraction-free methods using dry swab have been shown to be advantageous in these critical times by different studies. In this work, we show the temporal stability and performance of the dry swab viral detection method at two different temperatures. Contrived dry swabs holding serially diluted SARS-CoV-2 strains A2a and A3i at 25{degrees}C (room temperature; RT) and 4{degrees}C were subjected to direct RT-PCR and compared with standard VTM-RNA based method. The results clearly indicate that dry swab method of RNA detection is as efficient as VTM-RNA-based method in both strains, when checked for up to 72 hours. The lesser CT values of dry swab samples in comparison to that of the VTM-RNA samples suggest better sensitivity of the method within 48 hours of time. The results collectively suggest that dry swab samples are stable at RT for 24 hours and the detection of SARS-CoV-2 RNA by RT-PCR do not show variance from VTM-RNA. This extraction free, direct RT-PCR method holds phenomenal standing in the present life-threatening circumstances due to SARS-CoV-2.
ABSTRACT
SARS-CoV-2 pandemic is having a devastating effect on human lives. Individuals who are symptomatic/asymptomatic or have recovered are reported to have/will have serious health complications in the future, which is going to be huge economic burden globally. Given the wide-spread transmission of SARS-CoV-2 it is almost impossible to test each and every individual for the same and isolate them. Recent reports have shown that sewage can be used as a holistic approach to estimate the epidemiology of the virus. Here we have estimated the spread of SARS-CoV-2 in the city of Hyderabad, India which is populated with nearly 10 million people. The sewage samples were collected from all the major sewage treatment plants (STPs) and were processed for detecting the viral genome using the standard RT-PCR method. Based on the average viral particle shedding per individual, the total number of individuals exposed to SARS-CoV-2 (in a window of 35 days) is about 6.6% of the population, which clearly indicates the rate of community transmission and asymptomatic carriers is higher than the number of reported cases. It is important to note here that the samples collected from the inlet of STPs were positive for SARS-CoV-2, while the outlets were negative indicating the efficient treatment of sewage at STPs. These studies are going to be essential to manage the pandemic better and also to assess the effectiveness of control measure.
ABSTRACT
Rigorous testing is the way forward to fight the Covid-19 pandemic. Here we show that the currently used and most reliable RT-PCR based SARS-CoV-2 procedure can be further simplified to make it faster, safer and economical by bypassing the RNA isolation step. The modified method is not only fast and convenient but also at par with the traditional method in terms of accuracy, and therefore, can be used for mass screening. Our method takes about half the time and is cheaper by about 40% compared to current most widely used method. We also provide a variant of the new method that increases the efficiency of detection by about 20% compared to the currently used method. Taken together, we demonstrate a more effective and reliable method of SARS-CoV-2 detection.
