By Mohun Aujayeb
We were all expecting that Covid-19 that came like a terrible cyclone will subside. But it has continued to gather momentum, staying with us and causing as much damage as it did initially. New strains keep emerging and making our fight against it strenuous, as if it is neutralizing our armour each time we build a new one.
The fight in principle is twofold. The first one is to stop infection and prevent transmission of the pathogen – the virus by adopting covid appropriate behaviours. These include personal hygiene, washing of hands on a regular basis, using sanitizers, wearing masks, maintaining social distancing. We are also careful to change clothes and take a proper shower when we come back home from work, the market or shopping spree, etc.
The next step is to become immune to the disease. Once immunized, should we be exposed to the virus and get infected our body will hopefully be equipped to resist he disease and its serious effects. Immunity offers that protection and very importantly prevents transmission of the virus to others. Immunity comes from already having had the disease as well as being vaccinated against it. Vaccination is a process wherein the treated virus antigen is injected into the body and the body in some way is duped to produce a defence mechanism – antibodies to kill the specific virus, and thus develops acquired immunity. The body also develops memory cells that respond to any future invasion of the virus by increasing its defence artillery. By vaccinating a considerable number of people in a population, we start building collective defence against the virus so that isolated sparks of infection burn out instead of spreading into an outbreak. This concept is referred to as herd immunity.
In herd immunity people who are immune become shields, preventing the virus from using them to continue the transmission chain to another person. It in no case means that the other persons are not susceptible to infection. It simply means a good number of people are acting as a shield to prevent the spread of infection. What is the percentage of population that needs to be vaccinated is not a standard figure. At present the WHO estimates a combined infection and vaccination percentage needed is 60% so as to achieve herd immunity. In the US, the number is set around 75-85% . And with the emergence of highly transmissible variants, some experts feel that 90% of the population should be vaccinated to reach herd immunity.
From the above, it seems that the vaccine is our saviour. And our objective is to achieve herd immunity which reduces the “reproductive number” (R number) of the disease (R number is the average number of people an infected person will pass a disease to). In this way as more persons get vaccinated and become immune, an infected person will pass the infection to fewer persons. When the R number reaches below 1, the disease starts to die out .
But let’s not rejoice. Scientific literature scientific and other media are replete with words of caution: the efficacy of the covid vaccines is not definite. We are still struggling to know how long a vaccine (of 2 shots ) will remain effective. Or to what extent will the immunity provided by the current vaccine/s be effective against mutated strains? Shall we need a third dose/vaccine boosters to maintain our individual immunity and herd immunity, and counter another surge and an unbridled spread?
For the time being we need to adopt and adapt Covid appropriate behaviours and get the vaccine so that we can live with the virus. It’s a new era that has dawned.
* Published in print edition on 6 July 2021
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