What is your view on development of herd immunity in Covid-19 and it's future prospectives?
Herd immunity theory will not be effective to protect populations against coronavirus.
WHO: 'herd immunity is scientifically and ethically problematic' Matthew Weaver 12 Oct 2020, The Guardian The WHO has warned that the number of new Covid cases is at its highest level since the start of the pandemic. Speaking at the regular Monday press conference in Geneva, Tedros Adhanom Ghebreyesus, the organisation’s director general, said: “Each of the last four days has seen the highest number of cases reported so far.” He added: “Around the world, we’re now seeing an increase in the number of reported cases of Covid-19 especially in Europe and the Americas.”
If by "herd immunity" we mean protection by exposure to the infection, herd immunity for Covid-19 will take time and will come at a great cost in morbidity and mortality. It is cynical to employ this as a main public health strategy. It is one thing to discuss herd immunity as an outcome of the course of this illness, quite another to promote it, as Sweden has done, as a means of dealing with this pandemic. Sweden accomplished little or nothing economically which was its stated goal, has outcomes that are much worse than its neighbouring countries, and could rightly be regarded as cynical and callously indifferent to the suffering of its own people.
If by "herd immunity" we mean to include both infection and vaccination, it is a concept signifying at what level infection or immunization of the population confers protection. We need to consider the infectiousness of the virus which assumes that everyone is equally susceptible which we know is not true for this virus. And this means we need to protect the most vulnerable parts of the population which is sadly, tragically not occurring at a predictable and workable level to make a real difference.
"For the pandemic to stop, the coronavirus has to run out of susceptible hosts to infect. Herd immunity occurs when enough people in a population develop an immune response, either through previous infection or vaccination, so that the virus can’t spread easily and even those who aren’t immune have protection."
"To reach herd immunity for Covid-19, public-health authorities estimate that around 60% to 70% of a given population would need to develop an immune response to the virus. Some epidemiologists and mathematicians now say herd effects might start to kick in before that point, at perhaps closer to 50%, suggesting potential protection could be achieved sooner."
"Still, infectious-disease experts adamantly warn against the notion of trying to reach herd immunity to the coronavirus without a vaccine, as the costs on human life would be staggering and it likely wouldn’t happen soon, if at all."
"The herd-immunity threshold is mathematically dependent on the infectiousness of the virus, or how many individuals each infected person goes on to infect—called the basic reproductive number, or R0. Scientists calculate the herd threshold using that number and an equation formulated almost 100 years ago by two pioneering Scottish epidemiologists."
"Measles, for example, is extremely contagious. It has a basic reproductive number between 12 and 18 and a herd threshold of 90% to 95%. For SARS-CoV-2, the basic reproductive number is estimated at around 2.5 to 3, implying a herd threshold of 60% to 70%."
"But the classic equation makes an assumption—that everyone is equally susceptible to infection and has the same chance of bumping into every other person, like molecules of gas in a bag, said Justin Lessler, associate professor of epidemiology at Johns Hopkins Bloomberg School of Public Health."
“Which of course is ridiculous. It’s not how the world works,” Dr. Lessler said. The equation gives you a good target for vaccine coverage, but it doesn’t capture the dynamics of an epidemic moving naturally from person to person, he said."
Citations are from this article:
https://www.wsj.com/articles/what-it-would-take-for-herd-immunity-to-stop-the-coronavirus-pandemic-11600594201?mod=hp_lead_pos7
Vincenzo Di Nicola, MPhil, MD, PhD
Professor of Psychiatry
University of Montreal
Will not agree with @Hermann. To achieve herd immunity we need at least 60-70% of our population to be exposed to this novel strain. Are we going to take this risk and allow this to happen. God knows how much more time will be required to achieve this level of immunity in the society...this virus does not affect every individual with the same intensity...thus the laws of infectiousness to calculate herd immunity on the basis of reproductive number will not stand good here....we should pray for a effective vaccine so that the human race can be prevented from extinction.
I totally agree with Vincenzo Nicola
I just reaffirm two points
To achieve protective herd immunity, we need
1. High proportion of infected and or immunized popoulation may be up to 80%
2. The immunity developed in response to infection or immunization must be protective for at least few years
Please have a look at this link.
https://academic.oup.com/ajcp/article/155/4/471/6063411
We better understand COVID-19 immunity, it is not possible to know how much of a. population is immune and how long that immunity last for. Recommendation from WHO. Advice for the public hoped for herd immunity, when enough people are protected through vaccination or past infection to stop the spread of Covid-19. What herd immunity implies is that when most of a population is immune to an infectious disease this provides indirect protection to those who are not immune to the disease. However, what “most” means is subject to interpretation.
Also, see the link below.
https://media.nature.com/original/magazine-assets/d41586-021-00728-2/d41586-021-00728-2.pdf