We know that for herd immunity, if a fraction of the population has immunity to COVID 19 pathogen, the likelihood of an effective contact between infected and susceptible hosts is reduced, since many hosts are immune and, therefore, cannot transmit the pathogen. I wish to know what will be the percentage required for such immune people in Indian context
It depends first of all on the Basic reproduction number R0. It can be estimated with initial data just after the spread of the virus had begun. Let’s say it is 1,5 – than with a little bit over 35% infected you will already reach herd immunity. But that is only the theory. In reality it will be very difficult to estimate R0 due to 2 reasons: (1) lack of good data and (2) early measures that brought the R down before it is possible to estimate R0 without measures (lockdowns masks and so on). An idea about the huge under estimation of cases you can find on this page, which collects prevalence studies from all over the world (more than 60 now): https://docs.google.com/spreadsheets/d/1zC3kW1sMu0sjnT_vP1sh4zL0tF6fIHbA6fcG5RQdqSc/edit#gid=0
Finally I believe that herd immunity in India will be reached earlier than in European countries for one single, but very important reason: Children are affected to a much lesser degree and Indias population is much younger! Also herd immunity can be reached much sooner if at least some of the measures like hand washing and mask wearing are continued.
According to many studies it has been found that if about 40 % of our population achieves herd immunity. It although completely depends upon the R0 value but it is really difficult to estimate its correct value as we will not be able to give a correct answer for the total number of persons infected from a confirmed COVID-19 individual.
Bad omen for herd or significant immunity after recovery from COVID-19.
See the latest article to know why?
Prevalence of IgG antibodies to SARS-CoV-2 in Wuhan – implications for the ability to produce long-lasting protective antibodies against SARS-CoV-2
https://www.medrxiv.org/content/10.1101/2020.06.13.20130252v1.full.pdf
