Questions have been raised regarding infectivity and virulence of the virus and immunity in Indian population. Both the factors are interlinked. It is important to understand the thought behind it.
From the available initial data, it is clear that mortality due to COVID 2 is different in different countries – <2% in China, USA, India and high in Italy and Spain (upto 15%). Secondly, the exponential spread expected and seen in rest of the world is not seen in India till date.
This could be due to pro- active strong steps of the government. This also could be supported by other factors.
- Demographic advantage: Indian has young population. Highest mortality is reported in people above 65, smokers, co morbidities. This can explain the low virulence but not the infectivity.
- Climate: In general hot and humid weather plays safe for viral diseases. This is what explains all other seasonal flu’s . This also is true of most of other corona viruses. There are two studies from NIT, USA, which have shown some effect of these two parameters on the virus (again mathematical model). But that will defend us from the onslaught in coming months when temperatures peak in May and June. The relative defense, offered till now is not explained by that. But we hope this works to our advantage in coming months.
- Immunological defense of the Indian population or people living in entire southern hemisphere. This is considered to be due to exposure to different infections by which our HLA system shows diversity and T cell immunity is stronger. There are some bioinformatics models to show that high endemicity of Malaria and BCG vaccinated population offers some inherent protection from this virus. In a recent Bioinformatics model, it has been shown that in Indians, a specific micro RNA mutates the virus and protects us. We are awaiting lab studies on samples for the same.
- Lastly comes the virulence of the virus. India was the fourth country in the world to isolate full genome of the COVID -2 virus. It shows 98.5% resemblance to the China virus. It is more or less same in USA as well. There is only one mutation. But in Italy, virus has shown some more mutations. Many people feel, this could be responsible for the increased mortality in Italy. Spain has probably same sort of mutation.
All these are important questions. Things are evolving. We do not have definite answers but will get them. Scientists all over the world are working on this.
Most important thing is to strictly follow the lockdown instructions and do not let the virus reach to a critical level, till we find the right drug for this or develop the vaccine.
