Epidemiology of COVID-19 and effect of public health interventions, Chennai, India, March-October 2020: an analysis of COVID-19 surveillance system

Jagadeesan M; Parasuraman Ganeshkumar; Prabhdeep Kaur; Hemalatha Masanam Sriramulu; Manikandanesan Sakthivel; Polani Rubeshkumar; Mohankumar Raju; Lakshmidevi Murugesan; Raajkumar Ganapathi; Mahalakshmi Srinivasan; Aswini Sukumar; Kumaravel Ilangovan; Madhusudhan Reddy; Divyadharshini Shanmugam; Prakash Govindasamy; Manoj Murhekar

doi:10.1136/bmjopen-2021-052067

Epidemiology of COVID-19 and effect of public health interventions, Chennai, India, March-October 2020: an analysis of COVID-19 surveillance system

BMJ Open. 2022 Mar 14;12(3):e052067. doi: 10.1136/bmjopen-2021-052067.

Authors

Jagadeesan M¹, Parasuraman Ganeshkumar², Prabhdeep Kaur³, Hemalatha Masanam Sriramulu¹, Manikandanesan Sakthivel⁴, Polani Rubeshkumar⁴, Mohankumar Raju⁴, Lakshmidevi Murugesan¹, Raajkumar Ganapathi¹, Mahalakshmi Srinivasan¹, Aswini Sukumar⁵, Kumaravel Ilangovan⁴, Madhusudhan Reddy¹, Divyadharshini Shanmugam¹, Prakash Govindasamy¹, Manoj Murhekar²

Affiliations

¹ Greater Chennai Corporation, Government of Tamil Nadu, Chennai, Tamil Nadu, India.
² Division of Epidemiology, ICMR - National Institute of Epidemiology, Chennai, Tamil Nadu, India.
³ Division of Non-communicable Diseases, ICMR - National Institute of Epidemiology, Chennai, Tamil Nadu, India kprabhdeep@gmail.com.
⁴ Field Epidemiology Training Program, ICMR - National Institute of Epidemiology, Chennai, Tamil Nadu, India.
⁵ Division of Non-communicable Diseases, ICMR - National Institute of Epidemiology, Chennai, Tamil Nadu, India.

Abstract

Objectives: To describe the public health strategies and their effect in controlling the COVID-19 pandemic from March to October 2020 in Chennai, India.

Setting: Chennai, a densely populated metropolitan city in Southern India, was one of the five cities which contributed to more than half of the COVID-19 cases in India from March to May 2020. A comprehensive community-centric public health strategy was implemented for controlling COVID-19, including surveillance, testing, contact tracing, isolation and quarantine. In addition, there were different levels of restrictions between March and October 2020.

Participants: We collected the deidentified line list of all the 192 450 COVID-19 cases reported from 17 March to 31 October 2020 in Chennai and their contacts for the analysis. We defined a COVID-19 case based on the real-time reverse transcriptase-PCR (RT-PCR) positive test conducted in one of the government-approved labs.

Outcome measures: The primary outcomes of interest were incidence of COVID-19 per million population, case fatality ratio (CFR), deaths per million, and the effective reproduction number (R_t). We also analysed the surveillance, testing, contact tracing and isolation indicators.

Results: Of the 192 450 RT-PCR confirmed COVID-19 cases reported in Chennai from 17 March to 31 October 2020, 114 889 (60%) were males. The highest incidence was 41 064 per million population among those 61-80 years. The incidence peaked during June 2020 at 5239 per million and declined to 3627 per million in October 2020. The city reported 3543 deaths, with a case fatality ratio of 1.8%. In March, R_t was 4.2, dropped below one in July and remained so until October, even with the relaxation of restrictions.

Conclusion: The combination of public health strategies might have contributed to controlling the COVID-19 epidemic in a large, densely populated city in India. We recommend continuing the test-trace-isolate strategy and appropriate restrictions to prevent resurgence.

Keywords: COVID-19; epidemiology; public health.

MeSH terms

COVID-19* / epidemiology
COVID-19* / prevention & control
Humans
India / epidemiology
Male
Pandemics / prevention & control
Public Health
Quarantine