Are Indians More Immune To Coronavirus Than The Rest?
Now the most common day to day word that everyone utters is “Coronavirus”. During December 2019 in the Wuhan District of China, doctors reported that few people had pneumonia-like symptoms, and the disease was later named as “Covid-19 (Coronavirus Disease 2019)”. Coronavirus is group of viruses known to cause respiratory illness.
Here are the top five countries affected by Covid-19:CountryCasesDeathRegionUnited States6,787,587200,171North AmericaIndia5,018,03482,091AsiaBrazil4,384,299133,207South AmericaRussia1,073,84918,785EuropePeru738,02030,927South America
Source: worldometers.info/coronavirus/countries-where-coronavirus-has-spread/, accessed on 16/09/2020
The population of India is 1,380,004,385. So 0.36% of the Indian population is affected by Covid-19 and the reported death rate is 2%. The severity of the disease is also less among Indians as evidenced by the rate of ICU admissions.
So the question that arises is “Are Indians more immune to coronavirus than the rest?”
Are Indians More Immune To Coronavirus than the Rest?
Though nothing can be concluded that Indians have better immunity against coronavirus, a few things can be hypothesized that are likely to be the governing factors in providing immunity to Covid-19 in Indians. The following are the factors that may contribute to immunity against Covid-19.
Indian SARS-Cov-2 Strains Differ From The Rest?
Host Factors
Food
Genetic Diversity
BCG Vaccines
Indian SARS-Cov-2 Strains Differ From The Rest?
Coronavirus, Credits: pixabay
Six genera of coronavirus are known to cause disease in humans and two (SARS-CoV and the Middle East Respiratory Syndrome coronavirus [MERS CoV]) are associated with severe outbreaks.
The Indian SARS-CoV-2 strains, unlike the strains elsewhere, are more closely related to bat-CoV RaTG13 (93% homology) than pangolin CoV (83.5% homology).
Phylogenetic analysis also reveals that there are two major lineages of SARS-CoV-2 genomes. The L lineage is supposed to be aggressive and contagious than S lineage. In India, the L lineage is more prevalent (95.7%) than S lineage (4.3%). L lineage is dominant in Gujarat, where surprisingly the fatality rate is also high.
So to conclude, strain difference has some impact on virulence and pathogenesis.
Host Factors
T helper cells, Credits: pixabay
The human immune system is very much molded by the environment and the diversity of microbes that an individual encounters in their lifetime.
Indians are exposed to huge microbial load early in life that confers broad-based immunity to the population. Since birth, Indians are exposed to a variety of pathogens like bacteria, viruses, fungi, and parasites. This exposure leads to the induction of immune responses.
Rathore et al., carried a comparative analysis to find whether there are any differences in immune phenotypes between Indians and Americans. The study revealed that Indian infants had a higher proportion of dendritic cells, monocytes, natural killer (NK) cells, memory CD4 + T cells, and naïve B cells, compared to American infants.
Also, India has an overwhelming burden of tuberculosis, malaria, and HIV, much higher than the developed countries. Due to such endemic disease, we are constantly subjected to pathogen-assault, invoking a more proactive-cell mediated immune response, than the Western population.
Though the role of chloroquine and hydroxychloroquine in the treatment of Covid-19 remains unclear, there is a possibility that frequent use of these drugs for the treatment of malaria in our country can confer protection against Covid-19.
Food
Herbs and spices like turmeric, cloves, ginger, mustard, saffron, cardamom, and garlic are indispensable ingredients of Indian cuisine. These spices contain bioactive compounds and phytochemicals that offer medicinal properties.
Turmeric contains a bioactive component called curcumin that has anti-inflammatory, antimutagenic, antimicrobial, and anticancer properties. Curcumin is proven to act against several viruses like Influenza Virus (H1N1, PR8, and H8N1), Herpes Simplex Virus (HSV) 1 and 2, Hepatitis B and C viruses, and Human Papillomavirus (HPV) types 16 and 18.
Similarly ginger is effective against the human respiratory syncytial virus.
Garlic possesses antiviral activity against HSV-1 and -2, Parainfluenza Virus type 3, and Human Rhinovirus type 2.
Though this evidences might be insufficient, these Indian spices may have some role in defense against SARS-CoV-2.
Genetic Diversity
DNA,, Credits: pixabay
Indian population has a great genetic diversity in the immune response genes called the Human leukocyte antigen (HLA) complex than the Caucasians. The HLA complex serves to induce and regulate immune responses. Several novel HLA alleles and haplotypes have been reported in the Indian population which may play a role in conferring immunity against SARS-CoV-2. Also, Indians have more KIR genes than Chinese and Caucasians.
BCG vaccines
A boy given a vaccine, Credits: pixabay
The BCG vaccine, given universally to Indian babies at birth for protection against tuberculosis, might confer some protection against SARS-CoV-2, probably through activation of T-cell mediated immune response.
Take-Home Message
Epigenetic factors play a crucial role in shaping the immunity of an individual.