Tamil Nadu — currently the second-worst-hit state in the country with COVID-19 cases — reported 69 new cases on Tuesday. Of these, 63 originated from a “single source” believed to be from Tablighi Jamaat. The state’s Health Department has stopped referring to the Tablighi Jamaat Markaz by name in an attempt to remove communal connotation.
The rise in positive cases has taken the overall state count to 690 as of April 7, with seven deaths. Of all cases, 636 were attendees of the Markaz.
What has puzzled observers though is the fact that Tamil Nadu, the state with the second-highest COVID-19 cases in the country is likely testing samples way below its optimum capacity.
Only 289 samples tested in 24 hours
“Till now, 5,305 samples have been taken for testing,” said a state health bulletin issued on Tuesday. Of these, while 690 samples tested positive, 4,414 samples turned out negative. Testing for 201 samples is currently underway. On Monday, the state’s daily health bulletin reported that 5,016 samples were tested.
This means that in a span of 24 hours, Tamil Nadu had tested an underwhelming number of 289 samples. In stark contrast to the total of 5,305 cases in the state (690 positive cases), Maharashtra has done 17,563 tests (1,018 positive cases).
The verdict seems clear: test more, detect more cases. The Tamil Nadu government, however, isn’t buying into the verdict. “If they have 14,000 kits why aren't they testing more?” asked political commentator, Sumanth Raman, referring to the comments made by Tamil Nadu health secretary, Beela Rajesh on the state’s more than sufficient supply of testing infrastructure.
Test only when required
The government’s defence is rather simple: test only on a need-to-test basis — or in other words, only when symptoms develop. “Those with symptoms of coronavirus shall approach government hospitals and get themselves tested and treated,” said a state health bulletin on March 16.
Indeed, this was a step up from an earlier bulletin, which made it clear that patients without travel history to COVID-19-affected countries do not need to be tested. Even the Chennai Corporation’s latest COVID-19 drive has officials knocking on residents’ doors, checking for symptoms, and not collecting samples, thus reaffirming the government’s symptom-first approach.
Single-source sample bias
Irrespective of whether or not the government is testing cases only on the basis of symptoms, the one instance that it has suspended its seemingly general rule of thumb, is for attendees of the Tablighi Jamaat Markaz in Nizamuddin, New Delhi around mid-March.
That the government has tested 1,475 attendees of the Markaz, with no specific insistence on symptoms, only to turn up with 636 positive cases points to one simple statistical flaw, that of sample bias.
A grand total of 1,475 attendees of the Markaz were tested because the probability of these attendees being coronavirus carriers was considerably high. So the question remains: if the Tamil Nadu government were to test more of its populace this way, would the state report more positive cases?
Rapid-test kits ordered
There is some semblance of hope that the state will test more samples in the future. Tamil Nadu health minister C Vijayabaskar has said that rapid-test kits were being imported from China to conduct random tests and possibly detect more COVID-19 cases.
“As per the chief minister’s instructions on rapid testing, we have placed orders for 1 lakh rapid-test kits through TNMSC (Tamil Nadu Medical Services Corporation),” Vijayabaskar told reporters.
In the event of more random testing and a departure from sample bias as in the case of testing attendees of the Markaz, a more clear picture would emerge on just how much of an impact COVID-19 has had on Tamil Nadu. Also, wider testing like in Kerala (10,221) and Maharashtra will help Tamil Nadu understand the spread and magnitude of the outbreak a whole lot better.
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