Dr. Purvish Parikh answers questions about Indian immunity and throws light on how we Indians could be fighting COVID-19.

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With global numbers crossing a million cases, we are staring at an unprecedented crisis due to the COVID-19 (SARS-CoV2) pandemic. The western world is reeling from healthcare infrastructure overflowing with serious patients and deaths numbering in thousands (Italy, USA, Germany, Spain, etc).

Geographical variations in the incidence, severity and mortality of COVID-19 have been well documented. Specifically, countries like India are not having such a high incidence of mortality. Some argue that the low numbers are because of inadequate testing. But could there be other reasons for the same? Are Indians protected to some extend from the COVID-19 virus? Perhaps most of us had a mild illness and recovered spontaneously.

We have previously reported in the Indian Journal of Medical Sciences that one of the factors giving immunity to Indians could be that we are living in a malaria endemic region. We believe that there is an inverse relation between past malaria exposure and COVID-19 infections.

Does having been exposed to malaria in the past also mean being exposed to viral RNA?

An analysis of published WHO data from 107 countries, comparing malaria incidence (per 1000 population at risk) data (from 2000-2017) and their number of COVID-19 positive cases till 24th March 2020, showed that the incidence rate of malaria and natural number of COVID-19 cases were inversely related at 95% confidence level (P-value < 0.0004; highly statistically significant).

Source: Feachem RG et al. Shrinking the malaria map: progress and prospects. Lancet. 2010 Nov 6;376(9752):1566-78.
 

How is this possible?

The answer is quite simple. The malaria parasite Plasmodium vivax carries with it Matryoshka RNA virus 1 (MaRNAV-1). Genomic sequencing shows that it shares a 93.75% identical sequence with that of the surface glycoprotein coding region of COVID-19 virus. This means that many Indians (especially adults) have already been exposed to a significant viral protein associated with malaria. Our immune system is therefore already primed to attack the surface glycoproteins of COVID-19 – basis for pre-existing immunological memory among Indians.

Is there any evidence that BCG vaccination confers a protective immunity against viruses?

Introduced mass BCG vaccination in 1948 and is currently part of our universal healthcare program. Earlier BCG Vaccination was shown to be effective in reducing the intensity of SARS infections. In the COVID-19 pandemic, those geographies that have the most cases (western world) had stopped their universal BCG vaccination from 1963 onwards. In fact, Australia and Netherlands have already commenced trials using BCG vaccine to protect their healthcare professionals against COVID-19.

While both these factors look promising to attenuate the impact of COVID-19 amongst Indians, we await further data to verify the real impact in protecting against the current global COVID-19 pandemic.

Disclaimer- The views and opinions expressed in this article are those of the author's and do not necessarily reflect the official policy or position of M3 India.

The author, Dr. Purvish Parikh is the Group Oncology Director & Professor of Medical Oncology at Shalby Cancer & Research Institute, Ahmedabad.