|Year : 2020 | Volume
| Issue : 3 | Page : 189-191
COVID-19: The curious case of the dog that did not bark
Department of Community Medicine, Dr. DY Patil Medical College, Hospital and Research Centre, Dr. DY Patil Vidyapeeth, Pune, Maharashtra, India
|Date of Submission||01-May-2020|
|Date of Decision||02-May-2020|
|Date of Acceptance||05-May-2020|
|Date of Web Publication||08-May-2020|
Department of Community Medicine, Dr. DY Patil Medical College, Hospital and Research Centre, Dr. DY Patil Vidyapeeth, Pune, Maharashtra
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Banerjee A. COVID-19: The curious case of the dog that did not bark. Med J DY Patil Vidyapeeth 2020;13:189-91
In a story from Arthur Conan Doyle's classic detective series, Sherlock Holmes speculates at the scene of the crime, “Why the dog did not bark?” Following up this lead solves the murder mystery.
The present pandemic of COVID-19 has a number of “Dog not barking moments,” which need to be explored. What are these moments in time?, the right term as the pandemic is still evolving and the dog may yet bark before the hurly-burly is over. The data presented in this editorial capture the moment as on May 3, 2020.
Western countries have better hygiene and sanitation with low population density than most Asian and African countries. Still, they are the worst affected not even the royalty being spared [Table 1]. And, the COVID-19 dog is yet to bark in South Asia and Africa [Table 2] and [Table 3].
[Table 1], [Table 2], [Table 3] compare how the pandemic has evolved in selected South Asian and African countries compared to some Western countries. The dog has been quite silent, so far, in these South Asian and African countries compared to the USA and the European countries. Most of the South Asian and African countries have very high population densities and large proportion of slum population conditions not conducive to “physical distancing” or frequent “hand-washing,” the measures touted as sheet anchors to control transmission.
This strongly challenges the evidence base of these measures at least in South Asian and African countries. None of these countries have reached double digits per million from COVID-19 deaths [Table 2] and [Table 3], whereas the USA and European countries have death rates from COVID-19 ranging from 200 to over 500 per million, the outliers being Germany with 79 deaths per million, and surprisingly, Belarus, which has not implemented lockdown, with just 10 deaths per million population [Table 1]. Besides Belarus, Sweden has also not implemented lockdown. Its death rate is comparable to other European countries, once again challenging the evidence base of drastic measures such as lockdowns for controlling respiratory infections.
Examples from India best illustrate this uncertainty. India's total slum population is more than 6.5 crores. This is almost equal to the population of the UK, France, or Italy and higher than the total population of Spain, as tabulated in [Table 1].
For more than a month, a sort of experiment is underway among this 6.5 crores slum population in India. They are cooped up in highly crowded living accommodations in the slums due to the lockdown as they cannot come out to the streets or go for work. Slums have limited water supply barely sufficient for drinking and cooking. People share common toilets. The lockdown in slum conditions achieved perhaps just the opposite of “physical distancing” and frequent “hand-washing.” If the same transmission dynamics applied to this population, the dog should have barked loudly by now. It has not, yet. The death rate even for the whole country of over 130 crores is just 1 deaths per million compared to 373–525 deaths/million in countries (France, Italy, the UK, and Spain) equal to the size or smaller than the Indian slum population of 6.5 crores.
Three possible explanations requiring confirmation by evidence are offered by population-level observations with the risk of ecological fallacies. First is the different demographic profile, particularly the median age of Western countries being higher compared to that of African and South Asian countries. It is evident from the tables that the median age of most Western countries is more than a decade higher than that of most South Asian and African countries. There is a powerful interaction of demography and age-specific mortality from COVID-19, with older ages more vulnerable. The much younger population of South Asia and Africa may be cushioning the impact of the pandemic.
Another effect modifier may be the higher overweight prevalence among the Western people compared to those of South Asian and most of the African countries. As obvious from [Table 1], [Table 2], [Table 3], the prevalence of overweight is almost two to three times more in the Western countries as compared to those in South Asian and most African countries except for Egypt and South Africa. Obesity has been established as a major risk factor for both severity and fatality from influenza and respiratory infections. Besides, it may be a surrogate marker for noncommunicable comorbidities, increasing the case fatality rate for COVID-19 infection. An interesting observation from [Table 3] is that the countries in Africa with the largest prevalence of overweight, i.e. 63.5% in Egypt and 53.8% in South Africa, had 4 per million and 2 per million deaths from COVID-19, respectively, the highest fatalities by African standards but still far lower than that of Western countries. The much higher overweight prevalence in these two African countries compared to other countries in the continent increased the death rate by 5–10 times.
Lastly, it has been postulated that past infections with other coronaviruses may offer some cross immunity toward COVID-19.
It is possible that factors such as lower age of population, lower prevalence of overweight, and past infections with other coronaviruses may be acting in isolation or more likely synergistically to cushion the impact of COVID-19 in Asian and African countries where a large proportion of urban population live in slums. In many instances, the slum population exceeds the size of many European countries; physical distancing and frequent handwashing practices can be observed by only more privileged populations. Given these ground realities in poor-income countries, one would have expected that COVID-19 pandemic would spread like a wildfire among the crowded populations of Asia and Africa. This has not happened, but to our surprise, the mortality from COVID-19 is many hundred times more in the more privileged continents compared to underprivileged continents such as Asia and Africa.
To conclude, the reasons offered for the “dog not barking” are hypothesis-generating deductions, with a caveat that they are based on incomplete information and uncertainties at a particular moment in time. Deductions have to be updated as more data are available particularly post lockdown when many countries will be relaxing the containment measures.
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[Table 1], [Table 2], [Table 3], [Table 1], [Table 2], [Table 3]