Home Features Dr EAS Sarma Cautions About Rapid Coronvirus Testing

Dr EAS Sarma Cautions About Rapid Coronvirus Testing

Dr EAS Sarma IAS (rtd)
(EAS Sarma)
I have corresponded with you (union health minister Harshavardhan) time and again on your Ministry’s  anti-COVID19 efforts. Let me compliment your Ministry for the relentless effort made so far.
I write this letter as a concerned citizen with particular reference to the Containment Strategy Guidelines issued recently by your Ministry. In the case of AP where I reside, there are many containment zones already identified and the State govt has started undertaking tests on a large scale.
As far as the public are concerned, they are aware that there have been occasional violations of the lockdown restrictions and there have also been instances of quarantined persons breaking the rules. In other words, it is possible that even during the lockdown period, those infected would have spread the virus to the others. It is equally possible that there are many asymptomatic virus carriers moving around in the community.
In this connection, there are several questions lingering in the minds of the residents of my area. These are as follows.
How accurate are these COVID19 tests? 
Is it possible that rapid testing done on a mass scale fails to identify both symptomatic and asymptomatic persons, thereby endangering the lives of the others in these parts?

WHO has been recommending a much higher testing rate to be adopted by India. Has India missed out many virus carriers who have already entered the community and are likely to spread the virus far and wide?

While the government has so far identified some specific clusters as on date, is it likely that more and more clusters will emerge in the coming days? This is important as there was no airport screening in India for most of December 2019 & January 2020 and, even subsequently, screening was initially confined only to a few countries, whereas it was found later that several other countries in the East were also found to be prolific sources for the virus to spread to other countries.
Has there been under-reporting of virus cases?
In order to find some plausible answers to these questions, I have gone through your Ministry’s Advisories and the available scientific literature on COVID19. The following seems to be the position.
Your Ministry’s containment strategy is rightly based on identifying the clusters where the virus incidence has been particularly severe, ring-fence those clusters, carry out 100% tests on symptomatic persons and also a large percentage of tests on all the others so that one can pin-point the incidence of the virus in that cluster and take both preventive and curative measures. When tests are conducted on asymptomatic persons within a cluster, either 100% of them should be covered or, if it is not feasible, carry out tests on a statistically random basis on a fairly large sample so that one can say with a high degree of confidence that the results represent those of the population of the asymptomatic persons.
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The strategy adopted will be of great importance to ensure that India does not go the same way as some of the European nations have gone.
In particular, there are serious public concerns about the accuracy of testing for the virus.
An  ideal diagnostic testing should be both specific and sensitive, which means that people who test positive truly have the disease and none of the people carrying the virus slip through the test as a false negative. To the best of my knowledge, no testing approach can assure 100% accuracy.
The RT-PCR testing meets both these criteria, but at best with only 90% accuracy. That implies that even if one tests negative in this test, it is always possible that there is a 10% chance that he/she is positive. It is therefore necessary that, in every case, the same person should be subject to a second independent test to establish the result beyond any reasonable doubt. RT-PCR test takes considerable time for the result to come out. In a fast- evolving situation, certainly, rapid testing needs to be considered, provided it is accurate.
The rapid testing methodology, as I understand, is based on determining the presence of antibodies, IgM and IgG in a person to find out whether he/she is infected and has developed the antibodies. I understand that the IgM antibody arrives within five to seven days of the patient acquiring the infection, whereas IgG arrives later, when the person has recovered. The .results of rapid testing come out within less than an hour. However, according to the scientific evidence available, these tests are not as accurate as RT-PCR tests. Though they are rated to have 80% accuracy, in one reported case, Spain had to return Chinese-made rapid testing kits, as they had an accuracy of less than 30%. Even if these kits can provide an accuracy of 70-80%, the results obtained from them can be wrong in 20-30% cases.
It is also not certain whether those conducting the tests are adequately trained and whether there are any technical shortcomings in the way they are conducting the tests.
Considering the accuracy level of rapid testing, depending exclusively on it can be misleading. In the case of COVID19 which seems to be highly contagious, over-caution should be preferred to under-caution.
I am not sure whether in different States including AP, each and every rapid test is being invariably cross-checked w.r.t to a second independent test. When those conducting the rapid tests quickly declare a large number of persons to be negative, how far can such results be relied upon? This is one aspect that your Ministry should carefully look into.
I am sure that neither the States nor the Centre would like to take any chances whatsoever with the containment strategy. In my view, in the case of every cluster, there should be different levels of technical oversight, at least at two levels in the State and one centrally controlled level of scrutiny by way of a random sampling check. Would it be possible for ICMR to institute a system to make sure that that the test results reported by the State authorities are by and large consistent with the WHO prescribed testing norms?
The first few cases of COVID19 appeared in Wuhan in the first week of December 2019. Should not your Ministry obtain the information of the travellers coming to India from that time onwards from China and the other South Eastern countries, institute a system to track all those persons and those who had come in contact with them and subject each one of them to virus tests, especially tests to determine the presence of  IgG to know whether they were infected and whether they are carrying the anti-bodies of that type?
There are many districts where no virus cases have been reported, though both domestic and global travellers visited those districts by road, rail and air. Should not the govt cross verify and ascertain the actual position by carrying out random tests?
In my view, there should be public awareness of the relative advantages and disadvantages of  RT-PCR tests and rapid anti-body tests so that the testing process remains demystified to the public.
The number of COVID19 cases touched 12,380 on Thursday (yesterday), including 414 deaths. The spread curve is yet to show any signs of flattening. It is not known as to how many virus cases have so far gone unreported. Against this background, the govt should plan for the worst possible scenario and take no chances whatsoever.
I hope you will consider these suggestions urgently.
(Contents of the letter, Dr EAS Sarma wrote to Harshavardhan, union minister of Health)
(E A S Sarma, Former Secretary to GOI, Visakhapatnam)