As the COVID -19 causes another peak of destruction in the world, scientists are trying hard to get a safe and effective vaccine in the market as soon as possible.
But other than vaccine there is another way to control the virus by herd immunity.
Here we discuss herd immunity and its role in controlling the spread of the virus.
In any community, the virus spreads from one person to another, if the virus does not find a suitable host then the cycle of spread is broken. Thus if large the population becomes immune to the virus following infection then the virus can not spread further and that is herd immunity.
Herd immunity protects people who are at increased risk like babies and those whose immune systems are weak and can’t get resistance on their own.
How does a society develop herd Immunity?
There are two ways this can happen.
People can develop antibodies to fight against the virus when infected. This antibody lasts even after the infection has gone and prevents the further risk of infection. Thus if a large number of people get infected and become immune it will give rise to herd immunity.
Immunity can also develop after vaccination.
When does a society reach herd immunity? It depends on the reproduction number or R0. The R0 is the average number of people that a single person with the virus can infect if those people aren’t already immune. The higher the R0, the more people need to be resistant to reach herd immunity.
Researchers think that the R0 for COVID-19 is between 2 and 3. This means that one person can infect two to three other people. It also means 50% to 67% of the population would need to be resistant before herd immunity kicks in and the infection rates start to go down.
Covid -19 and herd immunity
The main problem with Covid 19 is that it’s a new virus and no one has immunity so the virus has the opportunity to infect more and more people.
We also dot know how long the immunity will last. If it behaves like a flu virus then immunity will last only for 1 year.
A large number of populations will have to recover from COVID-19 infection to get herd immunity it may be more than 70% of the population.
We hope that vaccine will be available before that happens.
Dr. Rakesh Rai. MS, FRCS, MD, CCT, ASTS fellow.