Herd Immunity

A raging debate is ongoing on Herd Immunity versus isolation. While herd immunity has been a de-facto nature’s standard for protecting the masses or herd, (not necessarily human alone), Coronavirus (SARS CoV2) has thrown this natural principle into question for several reasons – 1) it is new and has high mortality and morbidity due to its properties 2) we have no innate defense against it 3) Even the most highly industrialized nations have no capacity to accommodate the sick patients. Let us review the factors why we should not YET resort to Herd Immunity.

 

Before getting started, let us see a live example of herd immunity being practiced to counter Covid-19. Let’s visit Sweden (Updated May 4, 2020).

“herd immunity,” in which a critical mass of infection occurs in lower-risk populations that ultimately thwarts transmission. “relies more on calibrated precautions and isolating only the most vulnerable than on imposing a full lockdown.”

I am strongly convinced for Herd Immunity because that’s the only mechanism for mass protection at the lowest cost (understanding the collateral damage). Herd Immunity, should not be construed with the development of commensals, or symbiosis between the bugs and the host. Of note, let us understand the process of herd immunity and commensal development from an evolutionary basis. For these bugs (those existing in GI tract) the external environment is harsh and toxic. They cannot exist outside and so have taken refuge inside the host. Eventually, the host and the bugs take a symbiotic relationship or often, at least don’t harm the host unless in rare circumstances. Summarize to say that there is no evolutionary angle to this novel coronavirus. It is de-novo, not an adaptive organism.

Herd Immunity and Vaccination

Second, from the perspective of spreading immunity – understand that the collateral damage it may cause is irrespective of the value of the individual. At a theosophical and spiritual level, who are we to decide a 78-year-old should die or survive? We only have to create a judicious system to protect if we know the risk is higher in this population.

Biologically and from the perspective of Epidemiology, Herd Immunity, especially as it plays from a vaccine perspective, offers lesser chance unless a vaccine is introduced. It provides better protection when a vaccine is introduced in the population. They both have a synergistic effect. In fact, the lesser a population is vaccinated, the lesser the herd immunity phenomenon.

Despite, not knowing this Coronavirus ever existed, I strongly feel that Herd Immunity is best for general mass protection if the morbidity, as well as the mortality, are low and this is considering the varying Rho factors for various bugs.

UK and Sweden tried Herd Immunity and failed. In a partial sense, the US unknowingly imposed the principle of herd immunity (by not imposing the lockdown) and paid the cost. Today, the UK, the US, and Scandinavian countries all are reversing their stand on herd immunity. This is because of the grim reality of 20000 plus deaths in the US and several thousand deaths in the UK. Those sticking to Herd Immunity have taken a heavy toll because –

  • This is a new virus (as against the others which evolve) whose least quantity infects (S protein configuration, antiviral suppression, and cytokine storm)
  • There mortality and morbidity significantly high for the state to prepare and manage this huge tide.

Excerpts from Kevin Kavanaugh from the link cited below –

“Mitigation strategies can decrease a contagion’s R0. To decrease the total number of individuals with active infections, the R0 will have to be less than one. So, on average, each infected person spreads the virus to less than one person. When this happens, the epidemic will eventually burn out.

Herd immunity strategies rely on a significant portion of the population to become immune to stop the spread of the virus. The higher the R0, the larger the percentage of the population who must become immune before the total number of those with active infections decreases and the epidemic burns out. An R0 of 5 to 7 will require 80% to 85% of the population to become immune before the number of infected will start to decrease. Thus, it can be argued that without mitigation, the R0 will be far too high to be able to stop this epidemic with herd immunity. Almost all of the population would have to contract the infection before the epidemic would stop, which probably will not happen. The availability of a vaccine to prevent infections with pathogens having a high R0 is of utmost importance.

Other concerns are that immunity to coronaviruses which cause the common cold only lasts between 1 to 2 years and there is mounting evidence that cats and dogs may become infected, giving concerns of an animal host.

Thus, without a vaccine, this virus will be with us for some time. Herd immunity may slow the expanse of the epidemic, but it is not likely to meaningfully stop it without mitigation strategies. And there is significant concern that those who currently recover could be re-infected in the near future. Strategies of social distancing, not gathering in large crowds, wearing masks and protecting those at increased risk are required to manage this epidemic.Returning to life as usual with the dependence on herd immunity in a non-vaccinated population to control spread is almost certainly a false narrative”.

Thus, I feel, our ultimate recourse is our own defense – innate and adaptive complimented by herd immunity. The only reason, we are not resorting to herd immunity exclusively is because of the morbidity and mortality associated with this virus.

CItations:

https://www.nationalreview.com/2020/05/coronavirus-crisis-sweden-refused-lockdown-other-countries-following/ (Updated May 4, 2020)

https://www.infectioncontroltoday.com/covid-19/viewpoint-have-you-heard-about-herd-its-covid-19-fallacy (Kevin Kavanagh)

https://www.historyofvaccines.org/content/herd-immunity-0 (Animation)

https://www.aap.org/en-us/aap-voices/Pages/It-Takes-a-Herd.aspx (A simple scientific version)

https://www.technologyreview.com/2020/03/17/905244/what-is-herd-immunity-and-can-it-stop-the-coronavirus/

https://watermark.silverchair.com/cir007.pdf?token=AQECAHi208BE49Ooan9kkhW_Ercy7Dm3ZL_9Cf3qfKAc485ysgAAAlIwggJOBgkqhkiG9w0BBwagggI_MIICOwIBADCCAjQGCSqGSIb3DQEHATAeBglghkgBZQMEAS4wEQQM2OVG8xg2pfYzNM-QAgEQgIICBSi7ifrpZhiYGndgs3xVawidKzRobUyILH54jTeTTCVvKXxKjfGTstEXY_TVc27do_oKohDgo0nlz3sEmDDDyXdf08bkvBxpUii7mooK0y4Cuonz8aMhK7uIcSVRndSJMKxsIbyrpXVSlgjnaCC387cZvR4qtxWfBcQqadTp1SmLZjw2qFgFm-w6W5Z6lzhNeAo9T4z-I9fVbPBPIlHS5ja0OrR19tlb7-bqbhxSlHujS0BnE5vGEjkB3yukP_2fTAR-2tir3Kje3j0Ae8jjDw2jV2AcCxjCxI6d-AdHTOKaB0JDka3AtdPccwhK-aHmteNLQCqnf9LAPbKHp075g79itw-qyLDc2ymz3IQg5lAWgKu1KO_vMkbCwkdr0Mx196-Rta8ssMWA7BxYySK2_hzcXcNicgsyy63sjXK6VHTy5UZNgSOw_F80rslfOgrCeP_yU-lFkMXB0Ll_2PRTXV5npNHbi0CwP0C-2oaGBpAUKeLycCOIDphV7F7bKQSlaKW4kgRf-XH3bqtsjnezQWGk2NllH4l_ErIujEUBev0hTMAaTPTIEMXc6OO429S6zwpF8JHpzdsmPLDXypaadLjseQk3Goikt2WmOKQB50WdqkYMYSWlcO2SUxMDA7_HZi_SkZhRPIigFE9Ocgo23y5UxAjHk3C6k5HRTbN0mQSmmKEA4Ag

 

Click to access f26ca43be04880eaf4ad046a1f9408cb2e11.pdf

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