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LETTER TO THE EDITOR
Year : 2021  |  Volume : 14  |  Issue : 1  |  Page : 110-111  

COVID19: Why the Dog did not bark? The Explanation can be unearthed by Immunoepidemiology


Department of Biochemistry, Christian Medical College, Vellore, Tamil Nadu, India

Date of Submission13-May-2020
Date of Decision06-Jun-2020
Date of Acceptance03-Jul-2020
Date of Web Publication22-Jan-2021

Correspondence Address:
S S Prakash
Department of Biochemistry, Christian Medical College, Vellore - 632 002, Tamil Nadu
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/mjdrdypu.mjdrdypu_255_20

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How to cite this article:
Prakash S S. COVID19: Why the Dog did not bark? The Explanation can be unearthed by Immunoepidemiology. Med J DY Patil Vidyapeeth 2021;14:110-1

How to cite this URL:
Prakash S S. COVID19: Why the Dog did not bark? The Explanation can be unearthed by Immunoepidemiology. Med J DY Patil Vidyapeeth [serial online] 2021 [cited 2021 Mar 9];14:110-1. Available from: https://www.mjdrdypv.org/text.asp?2021/14/1/110/307670

Dear Sir,

Coronavirus Disease 2019 (COVID19) is an infectious disease pandemic that is caused by a novel coronavirus, severe acute respiratory syndrome-coronavirus 2 (SARS-CoV-2).[1] The disease has impacted the human population throughout the world, with some countries and regions affected more severely than the others. This has been brought out nicely by the editorial in this journal.[2] The future course of this pandemic is still uncertain.[1]

Just like in the story of “The Adventure of Silver Blaze” by Sir Arthur Conan Doyle, where Sherlock Holmes points out that the narrative does not include the bark of the dog, in the case of COVID19 in some countries and regions of the world, the narrative does not include significant numbers of severe or critical cases and/or deaths overflowing which could not have been missed unlike asymptomatic patients or those with only mild or moderate symptoms.[2] The question is not whether the dog existed or not, but why it did not bark the way it was expected. The editorial points to three factors that may account for the lower impact of COVID19 in some regions of the world. They include the age of the population, the percentage of the population who are overweight, and prior infections with other coronaviruses that are one of the common causes of the common cold.[2]

The epidemiological basis of a disease can be studied by the analysis of the classic triad of agent, host, and environment under different dimensions [Table 1]. The epidemiological factors would be helpful to explain the susceptibility, exposure, and risk of infection. The pathophysiological and clinical aspects of the infection can be ascertained by studying the viral and host factors. The contextual factors are essential to consider, which include the social demographics, environmental, and ecological aspects. The explanation of the outcomes in the current pandemic can be provided by an integrated analysis of the knowledge derived from all these domains. These can be contributed by the newer dimensions of epidemiology, such as molecular epidemiology, social epidemiology, and socio-temporal epidemiology of the disease.[3]
Table 1: Epidemiology and Coronavirus Disease 19

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The host factors would be expected to play a major role in the differential outcomes. These would include the physiology of the organ(s) affected, in the case of SARS-CoV-2, it is predominantly the lungs, preexisting conditions, and comorbidities. In addition to these, one of the most important host factors that may influence the outcomes would be the immunological responses of the host and the determinants of host-pathogen interactions. The immunological response itself can be considered under the framework of the integrated responses of the factors associated with the host, virus, and the context.[4] The field of immunoepidemiology would help us to understand the processes that contribute to the variations seen in individuals and populations for infectious and noninfectious diseases.[5] Epidemiological factors are somewhat stable compared to immunological factors, which are difficult to predict given the several known and unknown variables involving both the host and the virus, causing the disease. The reasons for differential outcomes can be deciphered by bridging the frontiers of knowledge of epidemiology and immunology.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
Biswas A, Bhattacharjee U, Chakrabarti AK, Tewari DN, Banu H, Dutta S. Emergence of novel coronavirus and COVID-19: Whether to stay or die out? Crit Rev Microbiol 2020;46:182-93.  Back to cited text no. 1
    
2.
Banerjee A. COVID-19: The curious case of the dog that did not bark. Med J DY Patil Vidyapeeth 2020;12:189–91.  Back to cited text no. 2
    
3.
Jacquez GM, Goovaerts P. The emerging role and benefits of boundary analysis in spatio-temporal epidemiology and public health. Spat Spatiotemporal Epidemiol 2010;1:197-200.  Back to cited text no. 3
    
4.
Ss P. Immune class regulation as an integrated response of factors related to host, stimulus and context. Scand J Immunol 2018;87:e12656.  Back to cited text no. 4
    
5.
Hellriegel B. Immunoepidemiology-bridging the gap between immunology and epidemiology. Trends Parasitol 2001;17:102-6.  Back to cited text no. 5
    



 
 
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