By the time I am writing this, I have already spent 47 days in lockdown and don’t know how many more days will be there. During this time, I have heard lots of people using the term herd immunity and wonder what it is?
So if we go with definition, herd immunity means “The resistance to the spread of a contagious disease within a population that results if a sufficiently high proportion of individuals are immune to the disease, especially through vaccination.“
Herd immunity can happen in two ways.
- A large number of people get infected and come-out of disease through a response from our immune system, that’s called natural immunity.
- By vaccination of a large number of people.
In short, when a large number of people become immune to certain diseases by natural means or through vaccination, it is called herd immunity, and that may help in containing the spread.
How does it work?
Let’s say there are 100 people in total, and 70% of them get the disease and come out of it. Our body has a protective shield against illness, which is called our immunity system. Our body develops antibodies to fight any disease; the antibodies remain even if we are cured.
So next time when we come in contact with the same illness, it won’t affect us because our body knows how to fight it. And that’s why it gets difficult for the virus to spread because so many people are immune to it, and the chain gets broken.
The contagiousness of any virus is measured by R0, which measures the number of people getting infected from one infected patient, and for Corona Virus, the value of R0 is between 2 to 2.5. so we can say one affected person affects the other 2 to 3 persons. The SARS CoV-2( Corona Virus) is less contagious than measles, which has the R0 value of 12-18 and more infectious than MERS, which has an R0 value of less than 1.
Will we get there?
For getting natural immunity naturally, it is assumed that 40-50 % needs to be infected and cured in some diseases. And we assume the same scenario for SARS CoV-2, with world population 7.8 billion, 3.4 billion people needs to get infected. We still don’t have the exact mortality rate, but with the current number’s that is somewhere between 2.5-4.5. By taking it 2.5%, 85000000 people will be dead. That’s a considerable number.
And the problem with SARS CoV-2 is that it’s a Novel (New), we still don’t know about it. We don’t know if a person contracts SARS-CoV-2 and develops COVID-19 more than once. So chances of natural immunity are bleak, and that left us with the development of vaccination.
So, What should we do?
SARS CoV-2 is here to stay, and we have to start living with it, at least till the vaccination is developed. Social distancing, better hygiene, and lockdowns are the only way to get some more time before the vaccine arrives.
Stay Safe-Stay Healthy.