An analysis of COVID-19 cases over the last few weeks shows how the pandemic has thoroughly spread across Tamil Nadu.

The State has added 1,02,572 patients since July 5, when the lockdown was relaxed across the State. While 26,441 (25.8%) of these cases came from Chennai, 17,317 (16.9%) came from nearby Kancheepuram, Chengalpattu and Tiruvallur districts. The remaining majority of 58,814 cases (57.3%) came from other districts. In contrast to the initial stages of the pandemic, when Chennai and its surrounding districts accounted for more than 75% of the cases, the region now accounts for below 60%.

This reduction is not due to a fall in cases in the Chennai region, but due to an increase in cases in other districts. While many districts reporting a high number of cases are from the southern districts, the spread is across all regions, with districts like Coimbatore and Salem in the west, Ranipet and Tiruvannamalai in the north and Tiruchi and Thanjavur in the delta also seeing a spike.

Growth in cases

On July 5, 21 districts had less than 1,000 cases, but on Sunday, there were only 11 districts with less than 1,000 cases. Similarly, in the same period, districts with 2,000-10,000 cases increased from just five to 20.

The number of deaths reported in the districts too has gone up, with 31 of the 37 districts reporting a marginal to significant increase in their Case Fatality Rates (CFRs).

As COVID-19 cases continue to surge in Tamil Nadu, the data below shows how the growth is driven by districts across the State in contrast to how the cases were concentrated around Chennai in the initial stages of the pandemic.

This graph shows the percentage of cases accounted by different regions when the State crossed the 50,000, one lakh, 1.5 lakh and two lakh marks on Jun 17, Jul 5, Jul 15 and Jul 25 respectively.

The regions have been classified as Chennai, the districts surrounding Chennai - Kancheepuram, Chengalpattu, Tiruvallur (*shown in the graph as KCT) - and Rest of Tamil Nadu (RoTN).

As the graph shows, while KCT and RoTN’s shares have increased over time, Chennai’s share has decreased.

Average cases

The visualisation below shows the average number of cases reported daily in each of these districts in the last three weeks and the total new cases reported in the whole three weeks period.

All the districts that reported an average of more than 100 cases a day in the last week have been included.

The cases getting reported daily have gone up in all these 19 districts, except Madurai, Dindigul and Vellore. While Madurai saw a considerable decline, the decline in the other districts were minor.

Fatalities

Deaths due to COVID-19 are also getting reported from many districts, The below table shows the ten districts that had  reported the maximum number of deaths in the past three weeks. The Case Fatality Rate (CFR) has gone up in 31 of the 37 districts in three weeks.