Indians have some genetic advantage, but these are still early days to come to any conclusion

The fewer-than-expected cases positive to the novel coronavirus (SARS-CoV-2) in Indiahave spawned severaltheories, one of them being,Indians being immune to the virus.

It is theoretically possible as Indians are constantly exposed to microbes that keep the immune system primed, destroying pathogens attempting to attack. This is why children in very clean environments fall sick at the slightest exposure to a pathogen a concept known as the hygiene hypothesis.

Indians have some genetic advantage as well: Theyhave evolved to gain more genes that protect against viral infections, according to Rajalingam Raja, director of Immunogenetics and Transplantation Laboratory at the University of California in San Francisco, US. He said:

These genes enable natural killer (NK) cells, a type of white blood cells in our body that provide a first line of defense against viral infections

Two families of genes KIR genes and HLA genes playa part in this protective function. Indians have more KIR genes than the Chinese and caucasians. This could makeIndians more immune to the virus, according to Raja.

A similar mechanismprotectsbats from viruses like Ebola and SARS. Bats are immune since they have expanded gene families that enhance NK cell function, said Raja, who first wrote about NK cells in 2008 in journal Genes and Immunity.

This alone is, however, not enough to guide Indias strategy to fight the disease or even suggest that strict measures are not needed. A team of researchers from India and the US studied umbilical cord blood of children in the two countries and found differences. The findings were published in journal PLoS One in 2018.

We interpreted our study to suggest that Indian babies could be more susceptible to early-life infections if they had lower frequencies of certain immune cells, said Holden Maecker, director of the Human Immune Monitoring Center at Stanford University School of Medicine.

Persistent pathogen assault especially early in life is almost certainly detrimental. Thisisseen in the phenomenon of environmental enteropathy, where kids with poor sanitation and high enteric pathogen loadsdevelop malnutrition and stunting, Maecker said. But he agreed exposure to pathogens could equip the immune system better to fight new assaults like Zika or coronavirus, to an extent.

This was similar to the protective effect provided by latent tuberculosis. It was certainly possible that there was increasing resistance if not specific immunity to COVID-19 in certain genetic groups. It is difficult, however, to extrapolate this to all Indians who are a diverse collection of ethnic groups.

It is a balance and my guess is that its too soon to say where Indians as a whole will fall on this balance in terms of their sensitivity to COVID-19, hesaid.

Arguments about the Indian immune systemsare mostly speculative, according to Satyajit Rath of the National Institute of Immunology. He co-authored the 2018 study with Maecker.

I am yet to see any indication that COVID-19 will, in fact, turn out to be less prevalent and/or milder in India, since the epidemic is still in its early stages in the subcontinent, he said.

There are no publications, as of now, on the differential prevalence or outcome of COVID-19 among Indians and those of other ancestries worldwide.

Good nutrition, exercise and sleep can improve the immune system.

We are a voice to you; you have been a support to us. Together we build journalism that is independent, credible and fearless. You can further help us by making a donation. This will mean a lot for our ability to bring you news, perspectives and analysis from the ground so that we can make change together.

More:
COVID-19: Do Indians have higher immunity to novel coronavirus - Down To Earth Magazine