If at all the virus is spreading stealthily in the community, Kerala has no idea how and where.
Rapid tests have not yet begun, the tests at Pothencode using the kits quite painstakingly purchased by Thiruvananthapuram MP Shashi Tharoor, because of the inappropriate choice of samples and timing, are feared to be inconclusive. The advanced testing Rajiv Gandhi Centre for Biotechnology had been asked to do among viral pneumonia patients of 10 private hospitals in each district has been done only in Thiruvananthapuram, and that too only in a limited manner.
Given the long waiting period for the results of RT-PCR (Reverse Transcription-Polymerase Chain Reaction) tests, now the most accurate method to detect the presence of the virus, antibody tests that can give results in about 15 minutes are seen as the best way to sense undetected virus activity in the community and intensify quarantine measures.
Pothencode in Thiruvannthapuram was the first place chosen for the rapid tests. Since the source of infection of Abdul Azeez from Pothencode who died of COVID-19 could not be found, there are fears that a silent carrier is unknowingly moving about infecting people in the panchayat.
Also, Shashi Tharoor managed to fly in 3000 kits from a private lab in Pune. As many as 33 people in Pothencode panchayat were identified and transported to the capital on April 4 for their throat swabs to be taken.
As it turned out, the kits Tharoor brought in using his MP funds were not rapid test kits that look for antibodies but the more accurate PCR kits that detects the presence of virus. “The RT-PCR machines we use now to get results have a two stage process. First it will extract the RNA virus and then, as the next stage, it will convert the RNA into DNA, which will then be amplified to check for the virus strain. The unique thing about the Tharoor kits was that it did both these stages, extraction of RNA and then its conversion into DNA, in one go. It was rapid only in that sense,” a top health official said.
If the normal RT-PCR tests used countrywide took four hours, the Tharoor kits could give the results in two-and-a-half hours. That is, only if a sample is positive, or in other words, was infected by the novel coronavirus (the RNA virus). If the sample does not have the RNA virus, in which case there is nothing to convert into DNA, both these tests take the same amount of time to provide the result. All the same, Tharoor's kit, which has the additional advantage of being portable, are as accurate as PCR machines used in our labs.
All the Pothencode samples, incidentally, were negative. This should in the normal case be a matter of big relief. But health officials are not particularly enthused. “A negative result means nothing at this stage. Even in a PCR test the virus can be detected only in the last two days of the incubation period, or only two days before symptoms start to show. We are not sure whether it was the right time to collect the samples of the people picked for the test,” the health official said.
There are three major worries about the tests conducted using Tharoor kits on April 4. One, was the timing right? “Some of the people chosen for the collection of swabs had come into contact with Abdul Azeez (the man who died on March 31) only a day or two before he had died. It will take at least six to seven days for the virus to make its presence felt in the throat sample. So a negative result, in such cases, has no value,” the health official said.
Two, have the right people been chosen? “People from the panchayat have been randomly selected but we are not sure whether they were the ones Abdul Azeeez had come into contact at mosques, weddings and funerals. That number must be more than 100,” the official said.
Three, did the administration get its priorities wrong? The question health workers ask is this: should we have gone ahead with such a costly test if the results would still remain inconclusive.
The tests done using Tharoor's kits have not ruled out community transmission. And, therefore, rapid tests will still have to be done in Pothencode once the antibody kits are ready.
Health officials Onmanorama talked to are of the opinion that Tharoor, though his intentions were highly laudable, should have been advised to use the money he had spent on PCR kits to purchase N-95 masks or PPE (personal protective equipments) kits for health workers.
Rapid but thoughtfully done tests
Any tests, be it viral (PCR) or antibody (rapid), cannot be done on a whim. There are certain protocols. “The first step is to quarantine a person, and only when the person starts showing symptoms should testing be done,” the health official said. It is said that some people selected for the test in Pothencode did not have any symptoms.
Even rapid tests are not done straightaway on those with even symptomatic influenza-like illnesses like cough, cold, low-grade fever and sore throat. These people are first quarantined for 14 days and only then a rapid antibody test is done on their blood samples. If they test positive for an antibody, then they are considered "probable COVID-19" and a confirmatory PCR test would be done.
If their samples throw up negative results, it is not as if they are freed of the virus. They will still be quarantined for 10 more days and a second antibody test would be conducted. This is done because a rapid test can identify antibodies only seven days after the incubation period; meaning, even if there are symptoms, a rapid test could still throw up a negative result if it is done before the virus shows up in the swab.
RGCB tests yet to take off
The RGCB's attempts to detect community transmission, too, has not gone anywhere. The RGCB was supposed to carry out PCR tests on viral pneumonia patients in private hospitals to check whether they were silent Sars-CoV-2 carriers. This was to be done in 10 hospitals each in all the districts.
“We have not got any positive results so far. But we have not done large samples, only about 20-30 samples in Thiruvananthapuram district,” RGCB director professor Radhakrishna Pillai M told Onmanorama. “So it is too early to say anything about community transmission,” he said. The director said that restriction on travel had impeded the extension of the project to other districts.
The rapid test kits developed by RGCB would be handed over to Indian Council of Medical Research on April 8.