COVID19: Coronavirus and Herd immunity

It’s not always that a virus harms us, sometimes our immune system kills us. Will get to that in some time. Herd means a large group. COVID19 a novel Coronavirus, sharing gene sequence with SARS virus. Why herd immunity is so important in this pandemic time? To understand, first, we need to know how our immunity and antibody response work.

‘The Battle’: Immune system vs COVID19

When a new virus enters our body, the body’s immune system is unaware of that virus. To tackle this foreign entrant, our immune system creates multiple combinations of antibodies. These antibodies are virus-specific. This research of special antibodies by the immune system may take time.

Once a successful antibody match is found the immune system starts making a copy. A copy of virus-specific antibodies like a printer does. It creates enough copies of antibodies so that it can kill every specific virus in your body. So, if you conclude that the number of antibodies forming will be directly proportional to the number of viruses we have in our body, then you are right.

Sometimes our immune system takes so much time that the virus multiplies and grows in very large number, and to kill all those viruses, immune system leaves you weak or creates some by-products that can be fatal. In the case of nCoV (CoVID19), the immune system creates a by-product fluid. This fluid forms in the lungs and fills in the lungs, causing your lungs to drown. Sometimes even death, due to lack of oxygen.

After successfully invading a virus, our immune system shuts down. Soon it produces memory cells. Memory cells remember the type of virus and specific antibodies which killed it. Now, next time whenever your immunity system encounters pre-dealt virus it directly creates specific antibodies which killed it last time. Hence the virus never multiplies in large numbers.

Herd Immunity: COVID19 brake

Think of a situation where a large number of the individual gets cured of COVID19. We will have a majority of the population who have developed immunity from the virus. Such individual no more remains a carrier of the virus and thus acts as a barrier in the virus spread.

But not everything is as simple as it seems. It doesn’t happen with every virus, as a virus can also mutate i.e., change their configuration, like influenza and HIV. For influenza, every year there’s a need for the altered vaccine as the virus mutates very fast. 

Current COVID19 context:

So what about CoVID19. Its status of mutation is still unknown. It shares its characteristics with SARS (a type of coronavirus), which has a history of mutation. But for the time being that mutation was not beneficial to the SARS virus. So, we may consider that if COVID19 mutates, that mutation will not be beneficial to it. But what if the mutation is beneficial? If that happens, the whole process of immunity and antibody and memory cells has to start again. Herd immunity will fail.