Mass Testing for SARS-COV-2 and Prevention of Next wave

Written By: / Articles / Saturday, 05 June 2021 17:24


By: Prof. Lisam Shanjukumar Singh
Head, Department of Biotechnology, Manipur University


Whether the deadly SARS-COV-2 is man-made or has naturally jumped from animal to human, it is now very clear that the weakest living virus particle has killed millions of people in a short time, the smallest living virus particle has put billion of human beings under house arrest and this simplest virus particle has become the highest authority of the world. If the virus is man-made, the people who have engineered the virus must be deeply regretful from the beginning of the pandemic if they are human and not a monster spraying lines of fire from their mouths across the continents. It is hard to know how many more people will be killed and for how many decades the virus will make us suffer like never before.
In India, many states have started mass vaccination and mass testing to curtail the spread of the Covid-19. Similarly, in Manipur, the government has launched the “Aggressive Mass Covid-19 Testing Drive” to identify the virus carriers. May I share some thoughts on the methods and management of mass testing in our state?
The prime objective of the mass testing/screening of SARS-COV-2 is to detect the virus if any person carrying the virus (both symptomatic and un-symptomatic) and to quarantine those carriers for preventing the spread of the virus to a virus-free (noninfected) person. Therefore, it is necessary to find the best method(s) of detection of the virus in human samples at the best possible level so that virus carriers are identified and the means to deliberately isolate the virus carrier from the virus-free people. In both cases of virus detection and isolation of virus carriers, we should not choose only the methods and means which are convivence to us. If we just use the methods of detection which are just convivence to us, the virus may escape undetected from the testing/screening and the person carrying the virus will be freely spread to other persons before becoming symptomatic or tested again and by that time virus is already spread to his/her four or five family members. If it is the case, the mass testing/screening will not serve its purpose and another wave (3rd and 4th waves) after the 2nd wave of COVID-19 may be very possible.

oja_sanju.pngIt is believed that the arrival of the second wave in Manipur is mainly because the testing methods used could not detect the virus during the first wave in some cases or positive persons were not isolated correctly. At the same time, if the public does not follow the guideline of the Government, the public is inviting the deadly virus. We all know that we are not a law-abiding society. However, I cannot comment much on that as I am not an expert in Social Science.
Rapid Antigen Test (RAT) and Real-Time Polymerase Chain Reaction (RT-PCR) are being used mainly in Manipur for testing. When roughly calculated the percentage about 25% to 40% of the testing done so far were tested by RT-PCR, 45%- 67% by RAT and only 7%-9% by TrueNAT/CBNAAT.
It’s a well-known fact that RAT can give a high number of false negatives because of the low accuracy of the test. A few months back (16th September 2020), the Delhi High Court pulled up the Delhi Government for choosing Rapid Antigen Testing (RAT), as the primary test of COVID-19 infection over RT-PCR (Reverse transcription-polymerase chain reaction) which is considered as the gold standard for testing as it gives nearly 100% accuracy.
Advantages of the RAT are; less time in testing (result in about 30 min per sample), very simple to run the test, cheap, no need for specialized technicians and machines, portable testing kits and high specificity. The disadvantage of the RAT is that it is not as accurate as of the standard RT-PCR tests for detecting the virus. Therefore, a significant percentage of those infected have passed the test as a false negative. In a few days, these persons will spread the virus among others, thinking they are healthy.
Although, the RT-PCR is highly accurate, there are disadvantages when coming to mass testing/screening. The disadvantages are; expensive, needs specialized trained persons and machines, not portable kits and time-consuming.
However, the advantages of the RT-PCR are; high accuracy, sensitivity and can test 94 samples (plus one negative and one positive controls) at a single test run. Although RT-PCR takes more time when compared to RAT, if we calculate the time consumed per sample for running the actual test, it is lesser than RAT. About 1 hrs to 1 and a half hrs will be consumed for running 94 samples on RT-PCR.
Moreover, many factors contribute to the consumption of time in getting RT-PCR results. Before the test run, the samples received have to be sorted out, make entry the details of the samples (names, age, address etc.) in the computer manually. After the results are out, details have to be upload to the portal manually.
However, if the above steps other than the test running are modified by using digital methods like barcoding while collecting the sample, manual data entry to a computer, sample sorting and portal uploading, the time-consuming in getting results will be reduced considerably. Another factor for consumption is the accumulation of samples at the testing centres due to the overloading of samples. There are some arguments from some section of people that there are some errors and false negative or false positive cases in RT-PCR testing. These errors and mistake are because of overloading/overpressure on the technicians as there are many steps involved in the RT-PCR testing and too many samples to run. However, accuracy and sensitivity also depend on the quality of the testing kit (enzymes, buffer, primers etc.) available to them. Therefore, the number of RT-PCR testing centre should be increased in the state to reduce the overloading/overpressure.
Therefore, coming to the Mass Testing for SARS-COV2, both the RAT and RT-PCR should be used tactically. RAT can be widely used. Those found positive in RAT should be isolated and those found negative should be confirmed by the RT-PCR test. In the confirmatory RT-PCR testing, those negative should be considered as the virus-free person at the time of testing and those found positive in the confirmatory RT-PCR testing should be isolated. If the above strategies testing is used and imposing stick isolation, there will be no much hole for the SARS-COV 2 to escape. At the same time, the Mass Vaccination program should be completed as the earliest. At the same time, people coming from outside should be tested by RAT and RT-PCR as above and isolated if positive rigorously.
If Government invests more resources in testing tactically described above and systematically isolation position persons, and the public bear some hardships by strictly following the Government’s guidelines and cooperating with the Government at the beginning of the Mass Testing, the 3rd or 4th waves of Covid19 can be prevented in our state. Therefore, a lot of government’s resource will be saved and the public will not go through hardship again and again. Otherwise, Government will keep on spending resources for another next wave of Covid19 and the public will face unbearable hardship.

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