Covid data released by Telangana continues to show statistical conundrums

Hyderabad: The daily Covid-19 bulletin issued by the state government continues to throw up statistical conundrums that are flummoxing even seasoned epidemiologists. The data presented every day by the government in the bulletins also shows that for every new positive Covid-19 case found over the past week, a large number of primary contacts are being tested.

However, surprisingly, irrespective of the number of tests performed each day, or the number of positive cases that are reported daily, the percentage of primary and secondary contacts has remained constant, at 44 per cent and 12 per cent respectively.

While the statistics are confounding in the least on this front, even more worrisome is the fact that irrespective of the number of daily tests, the number of positive cases has doubled between March 22 and March 28. While one out of every 165 persons tested positive for Covid-19 on March 22 (68,171 tests, 412 new cases), on March 28, these numbers stood at 33,930 tests with 403 positive cases, at the rate of one out of every 84 people tested turning up positive for the disease.

This is not the first time that data released on Covid-19 cases has been found to be statistically impossible. Consistencies in the data related to age groups of Covid-19 victims, or those who have died after contracting the disease but are classified as dying from comorbidities and not from Covid-19 infection, have remained the same for months.

The latest to join this category of statistical consistency are the numbers related to primary and secondary contacts being tested every day. For instance, on March 22, the health department said in its Covid-19 bulletin, that 68,171 tests were performed. It also said that 29,995 primary, and 8,180 secondary contacts were among those tested on the day, representing 44 per cent and 12 per cent of the day's total tests respectively.

Over the course of the next six days, while the number of total, primary and secondary contacts tested changed, what did not change was the proportion these two categories of people comprised in the total tests, which remained rock steady at 44 and 12 per cents.

Asked if such consistent numbers can possible in case of a highly infectious disease, Dr Ranga Reddy Burri, founder trustee of the Infection Control Academy of India, said "The numbers do not look correct."

Other epidemiologists that Deccan Chronicle talked to also said they were surprised at the numbers and how the same per centage of primary or secondary contacts happen to be turning up each day. Raising concerns over whether the true numbers are being presented to the people of the state, one specialist said "all you need is someone good at Excel sheets to fill numbers up."

Date Tests Primary* Secondary* Contacts**

March 22 68,171 29,995(44%) 8,180 (12%) 72

March 23 70,280 30,923(44%) 8,433 (12%) 71

March 24 56,464 24,844(44%) 6,775(12%) 50

March 25 57,548 25,321(44%) 6,905(12%) 48

March 26 58,029 25,532(44%) 6,963(12%) 52

March 27 57,942 25,494(44%) 6,953(12%) 47

March 28 33,930 14,929(44%) 4,071(12%) 37

*Tests done. Percentage of total tests for each category in parenthesis.

** Number of primary contacts per positive case

Data from TS health department's Covid-19 bulletins.