A new study found that the COVID-19 death rate is lower in countries with lower standards of hygiene, sanitation and water-quality as compared to countries with better hygiene and water-qualities.

The study from Pune’s National Centre for Cell Science (NCCS) and Chennai Mathematical Institute has not been peer-reviewed but is published as a preprint on Medix. It aimed to analyse the difference in COVID-19 mortality in different nations and aimed to “explore the dichotomy of rich and poor countries in relation to Covid-19 deaths.”

The results indicate that the worse the water sanitation in a country, the lower the COVID-19 deaths per million. However, it cautions against using poor hygiene as a disease coping mechanism.

The study looked at factors including the percentage of the older population, population density, the incidence of communicable and non-communicable diseases etc.

Dr Shekhar Mande, director-general, Council of Scientific and Industrial Research (CSIR) told The Indian Express that certain richer countries had demographic differences, better hygiene and higher incidence of autoimmune disorder that were linked to higher COVID-19 mortality. These factors better explained the link to COVID deaths than GDP, the paper argued.

Why does lower sanitation and therefore higher communicable diseases like malaria and dengue result in better immunity? According to the study, “As the parasite and bacterial disease burden is high in low and low-middle income countries, this can best be inferred upon by the “immune training” in the population of these countries due to chronic exposure to communicable diseases.” Paradoxically, better hygiene practices may reduce your immunity and increase your risk of autoimmune diseases, but on the other hand, hygiene and sanitation improvements can drastically reduce the spread of communicable diseases.

However, so far, there is no clear link to this proposed “immune training” resulting in lower COVID-19 death rates - but the study aims to explore this further.

(With inputs from The Indian Express )