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Epidemiology of SARS-CoV-2 Infection in Karnataka State, South India: Transmission Dynamics of Symptomatic vs. Asymptomatic Infections

14 Pages Posted: 22 Oct 2020

See all articles by Narendra Kumar

Narendra Kumar

National Institute of Mental Health and Neurosciences (NIMHANS) - Department of Neurovirology

Shafeeq K. Shahul Hameed

National Institute of Mental Health and Neurosciences (NIMHANS) - Department of Neurovirology

Girdhara R. Babu

Indian Institute of Public Health, Bengaluru

Manjunatha M. Venkataswamy

National Institute of Mental Health and Neurosciences (NIMHANS) - Department of Neurovirology

Prameela Dinesh

Government of Karnataka - State Surveillance Unit

Prakash Kumar BG

Government of Karnataka - State Surveillance Unit

Daisy A. John

Indian Institute of Public Health, Bengaluru

Anita Desai

National Institute of Mental Health and Neurosciences (NIMHANS) - Department of Neurovirology

Ravi Vasanthapuram

National Institute of Mental Health and Neurosciences (NIMHANS) - Department of Neurovirology

More...

Abstract

Background: In this report, we describe the epidemiology of SARS-CoV-2 infection, specifically examining how the symptomatic persons drove the transmission in the state of Karnataka, India, during the lockdown phase.

Methods: The study included all the cases reported from March 8 to May 31, 2020 in the state. Any person with history of international or domestic travel from high burden states, those presenting with Influenza-like or Severe Acute Respiratory Illness and high-risk contacts of COVID19 cases, who were SARS-CoV-2 RT-PCR positive were included. Detailed analysis based on contact tracing data available from line-list of the state surveillance unit was performed using cluster analysis software package.

Findings: Amongst the 3404 COVID-19 positive cases, 3096 (91%) were asymptomatic while 308 (9%) were symptomatic. Majority of the asymptomatic cases were in the age range of 16-50 years while symptomatic cases were between 31-65 years. Most of those affected were males. Cluster analysis of 822 cases indicated that the secondary attack rate, size of the cluster (dispersion) and occurrence of overt clinical illness is significantly higher when the index case in a cluster was symptomatic compared to an asymptomatic.

Interpretation: Our findings indicate that both asymptomatic and symptomatic SARS-CoV-2 cases transmit the infection; however, the main driving force behind the spread of infection within the state was significantly higher from symptomatic cases. This has major implications for policies related to testing. Active search for symptomatic cases, subjecting them to testing and treatment should be prioritized for containing the spread of COVID-19. 

Funding: The study is funded by an Intermediate Fellowship of the Wellcome Trust-DBT India Alliance (Clinical and Public Health Research Fellowship) to Giridhara R Babu, Grant number: IA/CPHI/14/1/501499.

Declaration of Interests: GRB and DAJ are employees of Indian Institute of Public Health, Bengaluru, Public Health Foundation of India and their employer had no say in the design of the study or the decision to publish. All other authors are employees of either state government (PD, PKBG) or NIMHANS (Central government). The employers had no role in the design of the study or the decision to publish. The authors declare that they do not have any other financial or non-financial relationships that could present a conflict of interest.

Ethics Approval Statement: This is to certify that the study entitled "Epidemiology of SARS-CoV-2 Infection in Karnataka State, South India: Transmission Dynamics of Symptomatic vs. Asymptomatic Infections" was reviewed and approved by the NIMHANS Institutional Ethics Committee (Basic and Neurosciences) in its 24th meeting held on 3rd June 2020 (Ref No.
NIMHANS/IEC/2020-21)

Keywords: SARS CoV-2 virus, COVID-19, epidemiology, Karnataka, Symptomatic Vs Asymptomatic

Suggested Citation

Kumar, Narendra and Hameed, Shafeeq K. Shahul and Babu, Girdhara R. and Venkataswamy, Manjunatha M. and Dinesh, Prameela and BG, Prakash Kumar and John, Daisy A. and Desai, Anita and Vasanthapuram, Ravi, Epidemiology of SARS-CoV-2 Infection in Karnataka State, South India: Transmission Dynamics of Symptomatic vs. Asymptomatic Infections. Available at SSRN: https://ssrn.com/abstract=3696841 or http://dx.doi.org/10.2139/ssrn.3696841

Narendra Kumar

National Institute of Mental Health and Neurosciences (NIMHANS) - Department of Neurovirology

India

Shafeeq K. Shahul Hameed

National Institute of Mental Health and Neurosciences (NIMHANS) - Department of Neurovirology ( email )

India

Girdhara R. Babu

Indian Institute of Public Health, Bengaluru

Manjunatha M. Venkataswamy

National Institute of Mental Health and Neurosciences (NIMHANS) - Department of Neurovirology ( email )

India

Prameela Dinesh

Government of Karnataka - State Surveillance Unit ( email )

Kengeri Post, Bangalore-Mysore Road
Bangalore, 5600 60
India

Prakash Kumar BG

Government of Karnataka - State Surveillance Unit ( email )

Kengeri Post, Bangalore-Mysore Road
Bangalore, 5600 60
India

Daisy A. John

Indian Institute of Public Health, Bengaluru ( email )

Anita Desai

National Institute of Mental Health and Neurosciences (NIMHANS) - Department of Neurovirology

India

Ravi Vasanthapuram (Contact Author)

National Institute of Mental Health and Neurosciences (NIMHANS) - Department of Neurovirology ( email )

India

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