Covid-19 fatality rates low in countries with poor hygiene, low-quality water: Indian study

Even as global Covid-19 mortalities continue unabated in some countries, a new study carried by scientists in India has found that countries having poor hygiene & sanitation standards and low-quality water provisions have a lower fatality rate from the virus as compared to richer countries where sanitation quality is high. 

According to the scientists, poor health and hygiene standards in India and many other countries along with poor quality of water may be having a beneficial impact on millions as their immune systems get naturally trained to fight the virus.

In a recent paper, the Indian scientists – Bithika Chatterjee and Shekhar C Mande from Pune-based National Centre for Cell Science, (NCCS) and Rajeeva Laxman Karandikar from Chennai Mathematical Institute – explored the higher prevalence of infection and deaths from Covid-19 in richer countries as opposed to poorer ones. 

Based on publicly available data for 106 countries on parameters like demography, prevalence of communicable and non-communicable diseases, BCG vaccination status, sanitation parameters, water supply etc, the study indicates that the poorer the water sanitation in a country, the lower the Covid-19 deaths per million.

The team collected all possible variables that quantify the cleanliness parameters in countries including the percentage of access to handwashing facilities, access to basic drinking water, availability of basic sanitation, prevalence of open defecation, safe drinking and safe sanitation. 

However, the study does not, in any way, promote pursuing weak hygiene as a disease coping mechanism.

“Per million population (deaths) number appears to be high in countries that are richer and having high GDP and (in) countries with low GDP, less number of people are dying, which is very paradoxical,” Mande, a former NCCS director, was quoted as saying in local news reports.

“One of the primary manifestations of Covid-19 has been a severe autoimmune reaction in the later phase of the disease. Among the reasons for rising prevalence in autoimmune disorders in western countries is proposed to be related to the ‘hygiene hypothesis’,” said Mande.

In the first few months of its deadly spread across the world, Covid-19 mortality has exhibited a wide range of variability across different nations. “In order to explain this phenomenon empirically, we have taken into consideration all publicly available data for 106 countries on parameters like demography, prevalence of communicable and non-communicable diseases, BCG vaccination status, sanitation parameters etc. We ran multivariate linear regression models to find that the incidence of communicable diseases correlated negatively while demography, improved hygiene and higher incidence of autoimmune disorders correlated positively with Covid-19 mortality and were among the most plausible factors to explain Covid-19 mortality as compared to the GDP of the nations”, the authors noted.

Higher GDP and improved Human Development Index (HDI) has led to improved sanitation and consequently reduction in the load of communicable disease burden in many countries. Interestingly, disease burden of non-communicable diseases now occupies areas of major concern in the higher HDI countries. Thus, a distinct correlation between HDI status of a country, and the prevalence of specific diseases has emerged in recent history, noted the study.

About half of the world’s population lives in low and low middle-income countries. Typically access to healthcare facilities, hygiene and sanitation is poorer in these countries and is often believed to be the contributing factor of higher incidence of communicable diseases in these countries. 

“Thus, it is not unexpected if infectious disease pandemics, such as that due to SARS-CoV-2, have catastrophic consequences in the low and low-middle income countries. Yet on the contrary, the disease prevalence and the Case Fatality Ratio (CFR) during the Covid-19 pandemic show a contrasting opposite trend in the low and low-middle income countries when compared to that of the high income countries”.

An interesting relationship between severity of Covid-19 outcome and several non-communicable disorders such as diabetes, hypertension, cardiovascular disorders has been noted, said the study, adding that among the many parameters that lead to non-communicable diseases, auto-immunity occupies an important place.