In the past seven days, the asymptomatic positivity rate in all districts across Karnataka has remained below 2.3%. While the decline is a huge relief, especially when compared to the rate a few months ago, a closer look at the data shows that when it comes to the positivity rate among symptomatic COVID-19 patients, there is a huge variation across districts during the same period.
While one district, for instance, managed to keep the symptomatic positivity rate as low as 0.2%, in another it was as high as 22.5%. According to analysis the State COVID-19 war room as on Sunday, the symptomatic positivity rate over the past week in districts such as Bengaluru Rural and Bengaluru Urban was as high as 22.5% and 22%, respectively. On the other hand, districts such as Koppal and Bagalkot had a symptomatic positivity rate under 1%.
Giridhar R. Babu, a member of the State’s COVID-19 Technical Advisory Committee, said that the percentage of symptomatic cases was an index of how active the district’s surveillance system was. “In districts with a higher proportion of symptomatic cases, it indicates that the syndromic approach [for detecting cases] is implemented well,” he said.
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The syndromic approach involves active case seeking on the part of health workers by looking out for and identifying people with COVID-19 symptoms. “Districts having a lower proportion of symptomatic cases indicates that they aren’t actively finding more people with symptoms,” Mr. Babu said.
He also pointed out that in districts with a higher proportion of asymptomatic cases, one would expect them to have higher cases with symptoms as well. “But the health administration has not detected those with symptoms.”
According to a doctor at a public health centre in Bengaluru, the number of tests conducted on symptomatic patients remains far lower than those conducted on asymptomatic patients, which had resulted in wide variations. “Many districts need to improve their outreach programmes and ensure that they test more people with symptoms. This will help in ensuring that the symptomatic positivity rate is low,” the doctor added.
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However, C.N. Manjunath, director of Sri Jayadeva Institute of Cardiovascular Sciences and Research, who is also part of the State’s COVID-19 expert committee, said the wide variation in symptomatic positivity rate could be the result of statistical error if the number of tests conducted among symptomatic persons is very low.