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Opinion

Covid-19: The Science Behind India’s Path | Analysis – analysis

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In the history of mankind, there have been several pandemics from Justinian’s plague in the 6th century to the Spanish flu (HINI influenza) in 1918. The 21st century has already seen three outbreaks related to the coronavirus: the severe acute respiratory syndrome ( Sars) in 2002, which claimed 800 lives, Middle East Respiratory Syndrome (Mers) in 2012 (862 deaths) and now coronavirus disease (Covid-19). Despite advances in the medical sciences, it is impossible to predict when the next infectious disease outbreak will take place. So we must be on full alert.

With India outpacing China in total number of infections, a comparison between the two is interesting in terms of infection trajectories. Compared to the most gradual increase in infections in India since mid-March, China witnessed a sharp increase in January and February, forcing the administration to impose a strict lockdown in Wuhan on January 23, two months before India, which lasted more than 70 days. at that time the curve flattened out and has remained generally static to date. The United States (USA) and Europe have shown a similar trajectory to that of China, which makes India somewhat atypical.

Notably, India recorded almost 45% fewer deaths than China, although active cases are still more than 60% of the total number of infected people, compared to almost zero in China. Recoveries of over 38% in India are higher than those of many nations at the same level of infection, although they are still lower than in European countries such as Germany, Spain and Italy. Furthermore, although the disease remained largely confined in China to Hubei province in general, and to Wuhan in particular, India witnessed more widespread infection in the four states of Maharashtra, Tamil Nadu, Gujarat, and Delhi, accounting for two-thirds of the total cases from India. .

Higher recovery rates are indicative of effective adaptive immunity that develops against the pathogen. On the other hand, the largely inherent immunity of the Indian population could explain the comparative lower mortality / severity rates observed so far. Right now, the important question is whether people who clear a SARS-CoV-2 infection can avoid the virus in the future. An answer to this will have implications for creating better vaccines.

Epidemiological and nutritional factors have been discussed to explain the population-specific differential susceptibility, progression, and severity / mortality of Covid-19 worldwide. However, deciphering the genetic polymorphism of the immunologically relevant genes influencing host immunity could reveal population-specific correlates of protection and / or vulnerability to the Covid-19 challenge.

The two most important are those that span the human leukocyte antigen (HLA) system and the Killer Cell Immunoglobulin Receptor (KIR) genes, which have evolved in humans to maintain a robust immune challenge to invading microbes. There is substantial data on the genetic propensity of the HLA and KIR systems in autoimmune and infectious diseases, including HIV / AIDS.

The highly polymorphic nature of the two genetic systems signifies their functional importance acquired during the course of evolution. They functionally regulate the body’s immune warriors, namely cytotoxic T cells on the one hand, and natural killer cells on the other, which directly attack the virus and help to kill it. A deep understanding of these in Covid-19 will be vital in developing effective screening tools to predict prognosis and response to therapy, including the design of individualized therapeutic strategies.

In the Indian context, scientists must find answers to two critical observations. First, the predominantly asymptomatic clinical course of the disease observed, and second, the rather limited number of serious and critical cases in India so far. Every effort should be made to discover measurable immune biomarkers that are predictive of severe disease and favorable treatment outcomes. Despite the limitations in understanding the mechanistic aspects of Covid-19 pathology, the challenge is to develop strategies to recruit innate and adaptive arms of the immune system against the virus. A recent study found that some people who have never been infected with SARS-CoV-2 harbor T cells that attack this virus, indicating that they may have been previously infected with other coronaviruses that share sequence similarities. Again, this is encouraging data for designing therapies.

The question is how long does it take to develop reasonably effective treatments for communicable diseases? Historically, while smallpox and polio took thousands of years to obtain an effective vaccine, HIV / AIDS took only 15 years before antiviral drug therapy was developed, although an effective vaccine has yet to be found. For Covid-19, the speed with which the global scientific community has come together, sharing knowledge and information on the unique task of defeating the new coronavirus, is unprecedented.

All eyes are currently on the World Health Organization-sponsored solidarity trial that tests, in addition to standard care, four different lines of short-term life-saving treatment regimens. The trial with thousands of patients worldwide from genetically different population groups will test the efficacy of the combination of remdesivir, hydroxychloroquine, lopanavir / ritonavir with or without interferon beta. Analyzing the population-specific influence of genetic systems could provide valuable information on the possible differential response to treatment and long-term protection. Identifying HLA variants in infected people can help predict the severity of infection and determine who would eventually benefit from a vaccine.

Science alone can motivate tomorrow’s healthcare providers to reach their full potential and offer life-saving devices to prevent and treat this and future viral pandemics. In this context, innovative technologies to deal with global emergencies are urgent needs.

Dr. Narinder Kumar Mehra is ICMR Emeritus Scientist and former dean of the All India Institute of Medical Sciences, New Delhi

The opinions expressed are personal.

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