The Kerala government, in addition to having reduced its testing numbers, has also been unable to trace the primary source of at least 38 COVID-19 positive cases. This is a sign of community spread in the state. This comes in the backdrop of an increased inflow of persons into the state from both within the country and abroad.
On May 28, Kerala sent only 1,819 cases for testing. From this pool, 84 tested positive, the highest number of COVID-19 cases in a day. Of these five were cases of local transmission, 31 were returnees from foreign countries and 48 are those who came back from other states. As of May 28, there are a total of 1,088 positive cases in the state.
According to the figures released by the Kerala government, 1,12,469 persons have reached Kerala from other States and countries - 91,966 came back by road, 12,388 by flights, 6,494 by trains and 1,621 by ships.
Kerala’s testing numbers were never this low as the state had been working to contain the virus by aggressive testing all through March, until the end of April. In March, India had done only 35,000 tests and the representative testing figures were just 26 tests per million of its population (ppm). Kerala had then done 6,034 tests (17.2% of total tests done in India) and 178 ppm. This was 6.85 times the national average.
By May 28, the situation has reversed. At least 33,62,136 COVID-19 samples have been tested in the country as of Thursday, May 28, which means the representative testing figures were 2,497 tests ppm.
Kerala, after the initial strong start, has tested only 59,548 samples for COVID-19 until now, which makes it only 1,687 tests ppm. This is much less that the national average.
By mid-April, when the COVID-19 outbreak began to intensify in other parts of the country, the virus was seen to have slowed down in Kerala. There was a perception that Kerala had been able to stall the indiscriminate spread of the Coronavirus. In line with that, the state began to test fewer samples by mid-April.
On April 14, only 240 samples were sent for testing. For the week preceding April 26, the average number of tests done per day in Kerala was only 502. Sure enough, the Kerala government was heavily criticised by the media in the state.
On April 28, the Kerala government announced that 3,101 samples were taken for augmented or random testing. The results of these tests found 3 people positive for Coronavirus and 2,682 persons tested negative. Two days later, on April 30, the Kerala government stated that a total of 3,128 samples (an addition of 27 samples) were taken for augmented testing.
Of these samples, 3,089 samples were found negative and 4 samples were found positive. Of the remaining, 21 samples were rejected, and 14 samples needed to be re-tested. Often, re-testing is ordered when the sample results are on the borderline between positive and negative or if the swab sent for testing was faulty.
After these four people tested positive, the government abruptly stopped the augmented testing. On May 2, the government added these samples to the day’s figures. Details of these four persons are not known – whether they are from four different districts or all from one district.
These four positive results from random testing indicate that there could be community spread in the state, because these samples were taken from the general public. They were neither people at home or institutional quarantine, nor were they health workers, who fall in the highly exposed category.
If the above tests, ie 0.13% of the samples, were to be extrapolated to the entire population of the state (3.5 crore), it would mean that there could be 45,000 positive cases in Kerala. Alternatively, these four cases could be outliers. Experts point out that to confirm whether these results from random samples is a pattern or an outlier, at least three cycles of augmented tests should be repeated.
The COVID-19 expert committee in Kerala is of the same opinion. It has been reported that the chairperson of the expert committee, Dr B Ekbal, on May 26, underscored in a meeting that it has become difficult to trace the source of infection in a number of cases. He was of the opinion that steps should be taken with the belief that community transmission had happened.
Ekbal said this in the backdrop of the state not being able to trace the primary source of at least 38 people, which includes health workers. But, the Kerala Chief Minister Pinarayi Vijayan said on Thursday that the sentinel testing that the state has been conducting confirmed that there was no community transmission in the state.
Sentinel surveillance is carried out to check the prevalence of a disease in a community. In Kerala, health workers, newspaper boys, police, supermarket employees, all those who are in the high-risk category, are being tested under this.
“This has nothing to do with the rest of the cases. It has to do with the natural history of infectious diseases. If I get COVID-19 tomorrow, I will not be able to answer who my primary disease contact in the last 15 days would have been for the obvious reason that at least 60% of the COVID-19 cases are asymptomatic. In all the above cases, we found the situation in which the disease could have been transmitted, but could not exactly pinpoint from whom the infection could have transferred. Then we checked if there was clustering of such cases. A similar instance happened in Palakkad, so we took samples of several people along the route where the person went,” explained Dr Mohammad Asheel, executive director of Social Security Mission under the Kerala government.
However, concurring with Ekbal was Dr T Jacob John, former head of clinical virology and microbiology departments, Christian Medical College in Vellore said, “All new infections are imported.”
“Once the virus came to Kerala, the state tried its best to prevent the transmission from the imported cases to their contacts. It was highly successful. But, COVID-19 is a respiratory-transmitted infection. So, as long as people breathe and speak, the virus will manage to spread. Kerala has porous borders and people are returning from overseas. So, the probability of the virus leaking into the community is extremely high,” pointed out John.
Once it leaks into the community, it will be picked up by people. “It can be found out by people who are falling ill and then being diagnosed for COVID-19 or by random testing or sentinel surveillance. Some of these people who should not have been infected, have been found to be infected. And then we may not know what to do with the results. The scientific way of answering the question is, ‘Yes, they are infected. We don’t know how they got infected’. This means the virus is slipping between our fingers. These cases cannot be called outliers,” underscored John.
It is a result that is difficult to interpret or accept, explained John, because the state did not expect to see people who had no contacts with those infected to be infected. Kerala was keeping a tab on all those who were infected. “So, now out of science you shift to emotional and psychological response. If you want to disbelieve it, you will say it is unimportant. If you wanted to believe it, you will say that this result is important and there is need to be vigilant. In public health, the latter is preferred to the former,” added John.
Kerala has mobilised its public health resources to it capability, said Asheel. “We have to check tests positivity, which is cases per million vs tests per million. This is what checks the adequacy of tests. If we conduct 1,000 cases in Kerala, the test positivity is 15, whereas it is 142 in Maharashtra.
The national average is 49, which means if 1,000 samples are tested, 49 turn positive. Tests positivity is what is more indicative of the cases in a population. In the sentinel surveillance, of the 9,937 people who were tested, only 24 tested positive (0.002%). The results of 1758 tests are awaited. What we should check is whether amongst these 24 cases, there is clustering, but there is no such cluster amongst those who tested positive,” explained Asheel.
If a positive case has been found, it can be termed an anomaly or an outlier, but public health professionals have to ask a few questions. “If those questions cannot be answered, they will accept it as community transmission. If you deny it, it is at your own peril. It comes down to a human psychological decision; it is an emotional response. Accepting it is a public health decision,” said John.
The virologist asked If Kerala was not expecting such results, then what were they testing additionally for? “What was the original purpose of the sentinel surveillance? Wasn’t it to find positive cases? When you find a positive case, you cannot sweep it under the carpet. They will have to test aggressively. I can imagine that Kerala maybe hurt a little bit that after doing so much good work, the virus got into the community. But, if they feel like that, they are not doing the right thing ethically,” added John.
Kerala has been successful in tracing the contacts of all those who arrived in the state. In Kerala the R0 is 0.4, when across the world it is almost 3. “We have done it by concentrating on our public health approach. We have increased our sentinel sampling to 500 samples per day from 1,000 samples a week in April. Kerala has the capability to test at least 3,000 cases a day and for that we have appointed 180 lab technicians,” highlighted Asheel.
R0, pronounced R naught, of an infection is the expected number of cases directly generated by one positive case in a population. So far, it has been understood that one COVID-19 positive patient infects three others.