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COVID19 and Repurposing of Drugs for Prophylaxis

Corona virus disease (COVID-19) has created pandemic in the world as declared by W.H.O. on March 12, 2020. It is a viral disease caused by SARS-CoV 2 virus and has affected large populations in 231 countries. There is no specific treatment available and management is empirical. On the backdrop of this novel corona virus (COVID-19-SARS-CoV2) creating a pandemic and resulting in lockdown of cities with sealing of the borders, it is an emergent need that the medical and scientific community undertake quick measures. This virus has made social, political, economic, financial, medical, and scientific fraternity to go in a state of emergency. The spread of the virus has been as fast as the dissemination of fear and false news. Rapid isolation measures (test, trace and treat), social distancing of two meters, hand washing with soap and water for 20 seconds or sanitizer and wearing of masks have restricted the spread. Yet, we still have not found solutions to treat the COVID 19 disease when it has affected individuals despite many drug and vaccine clinical trials that the world is looking forward to. We have also not been able to device methodology to prevent the occurrence of infection, to find drugs that can act as prophylactic medicines or drugs that can prevent the affected patient from developing severe lung injury and other complications that can ensue. Present commentary deals with some of these prophylactic measures.


INTRODUCTION
Coronavirus belongs to the family of coronaviridae in the order Nidovirales. There are four groups of coronaviruses 1 alphacoronaviruses infect mammals (human coronavirus NL63), Betacoronaviruses infect mammals (SARS CoV, MERS CoV, Bat CoV), gammacoronaviruses infect birds (avian infectious bronchitis coronavirus), deltacoronaviruses infect both birds and mammals (porcein delta CoV). COVID19 is a betacoronavirus 1 . Six species of human coronaviruses are known, with one species subdivided into two different strains, making seven strains of human coronaviruses altogether.
Three human coronaviruses produce symptoms that are potentially severe: Australia, B strain in East Asia, C strain is mutation from B and seen in Europe (not China).C strain is also the one in Hongkong , Singapore, S. Korea from where it went to Europe. USA and UK have detected G strain. Chinese scientists have labeled 2 strains that they found, L strain (70%) which is more aggressive and found early, and S strain which is less aggressive and comprised 30 %. As per a study from West Bengal 2 the original strain of the COVID-19 causing virus was named O type or ancestral type. But from this strain at least 10 different strains had originated. Out of these 10 new strains, a strain called A2a is currently the most prevalent in the world as well as in India. The study claims that if a vaccine is to be made, it should be made against this strain. The A2a strain reportedly has an advantage over its peers in that it can better bind with the ACE-2 receptors in the lungs -which is what the SARS-CoV-2 virus uses to enter healthy cells.
It was on February 11, 2020, that the international committee on taxonomy of viruses Given these facts about the CoVid 19 scenario, there appears to be an equally urgent need to device newer methods as under: 1. Prevention of SARS CoV2 viral entry -Physical methods, barriers.

Prevention of entry of SARS CoV2 virus in human body-Immunological boosting, vaccines
3. Prevention of entry of the SARS CoV2 virus by local chemical methods 4. Prophylaxis for arresting the viral multiplication in human host by drugs 5. Prophylaxis to prevent lung injury.

Prevention of SARS CoV2 viral entry -Physical methods, barriers.
These are all the methods adopted by the world like social distancing of two meters, repeated hand washing with soap and water for 20 seconds, sanitizers, wearing masks, head gears, not touching hands to nose mouth and eyes. Lock down of cities, staying at home and sealing borders for domestic and international travel are essential.

Prevention of entry of SARS CoV2 virus in human body.
Till such time that effective vaccines are made available, communities will rely on their innate

Prophylaxis for arresting the viral multiplication in human host by drugs.
In areas where physical barriers like social distancing is not possible due to high population density in slum dwellers, prophylactic drugs will be useful. These are drugs used for other indications and can be repurposed 8 .
Doxycycline is a broad-spectrum antibiotic with antibacterial, antiviral, and antiprotozoal actions. It has anti-inflammatory properties. Published literature 9,10 shows that it is effective in

Prophylaxis to prevent lung injury.
If the patient has developed the disease, the aim would be to stop lung injury. This is in addition to many antiviral drugs and other supportive empiric therapy. Repurposing oral polio vaccine to give protection against CoVid19 virus, by nonspecific boosting of immunity is being undertaken. All the five prophylactic strategies suggested will testify the truth. Obviously, the jury is still out.