In this article, I am not advocating any strategy towards herd immunity against coronavirus. I want to show that the mainstream discussion misses the point.

Note 1: If you are looking for some COVID-19 conspiracy theories, go elsewhere. Below are just numbers. Note 2: This is incomplete. I invite you to provide more data – I will provide proper citation if you do so. Note 3: This article is my private after-hours effort. It has no relation to the institutions I am associated with: my customers, employers or partners.

As I just heard in the BBC World News, the Netherlands are going to launch their coronavirus herd immunity experiment. As I understand, this is a program in which a large part of the society (originally a group of volunteers) may be infected with the coronavirus. The goal is to increase the proportion of the society which is immune to the virus, in order to eventually stop the disease from spreading. The BBC named this program controversial, without providing much ground to this statement. This got me interested and I spent some time trying to understand what makes this interesting idea controversial. Before you criticize this article, make sure you understand I am not promoting any particular strategy. I am not in a position to do so, because I am neither an epidemiologist, nor a medical professional and I know very little. I am a data analyst. I want to show what there is in the data.


The mainstream discussion about herd immunity misses the point. Some sources appear to be erroneous, some others are purposely falsified. The balance in the debate needs to be restored.

Instead of quoting those highly popular but low-quality materials, we should rather be actively looking for the best strategy to achieve herd immunity at minimal cost. It remains the only known mechanism to protect the population from the plague.

herd immunity, from Wikipedia

The scientific background

At the moment of writing this, the coronavirus has been spreading through the world exponentially, causing thousands of personal tragedies. In my previous article I provided argued that some of the statistics appear exaggerated, which however does not change the severity of the situation. As for today, governments and instutitions worldwide are generally in panic mode, implementing partial solutions that in most cases are not part of any strategy, sometimes possibly causing more damage than good. The strategies of fighting the disease are being invented on the fly, and none of them has been given enough time for proper field testing.

One widely quoted analysis is this paper from Imperial College London by Neil M Ferguson et al. from the Imperial College COVID-19 Response Team. The paper says:

Two fundamental strategies are possible: (a) mitigation, which focuses on slowing but not necessarily stopping epidemic spread –reducing peak healthcare demand while protecting those most at risk of severe disease from infection, and (b) suppression, which aims to reverse epidemic growth, reducing case numbers to low levels and maintaining that situation indefinitely. Each policy has major challenges. We find that that optimal mitigation policies (combining home isolation of suspect cases, home quarantine of those living in the same household as suspect cases, and social distancing of the elderly and others at most risk of severe disease) might reduce peak healthcare demand by 2/3 and deaths by half. However, the resulting mitigated epidemic would still likely result in hundreds of thousands of deaths and health systems (most notably intensive care units) being overwhelmed many times over. For countries able to achieve it, this leaves suppression as the preferred policy option.

Mitigation strategy simulation by Imperial College COVID-19 Response Team

The paper is well written, very logical, supported by solid research, data and simulations. Its conclusions are disturbing: in both scenarios, we are going to suffer enormous numbers of deaths. However, there’s one reason why the suppression strategy seems a better choice: because it delays the epidemy up to a point of possible delivery of a vaccine. An important thing to note is that herd immunity is discussed as a part and consequence of the mitigation strategy. This logically means that you could also try to achieve herd immunity using different strategies, besides the two mentioned in the paper, and perhaps more optimal.

Herd immunity (from Wikipedia)

Herd immunity is indirect protection from infectious disease that occurs when a large percentage of a population has become immune to an infection.

Many people think herd immunity contradicts vaccination. This is wrong. If most people are vaccinated, this results in herd immunity. The biggest challenge here comes from the anti-vaccine movement.

Herd immunity can alternatively be achieved by process of natural infection.

The herd instinct

The paper came out on 16th March 2020. What happened later can only be explained by the herd instinct. Apparently, these days the main narration of the COVID-19 story is in the hands of bloggers and influencers rather than medical professionals, epidemiologists or governmental agencies. This only tells us about the scale of the overall chaos and unpreparedness for the situation. Following the herd instinct, if some material appears to be trending, thousands of minor news agencies and bloggers rapidly quote it and accept it as the truth. Unfortunately, the well thought-through, hermetic academic data is rarely trending. So this is what I believe has happened.

The Imperial College material has been hijacked by Tomas Pueyo, an overnight COVID-19 influencer, public speaker and businessman with no epidemiology background, and chaotically pasted into his article The Hammer and the Dance. The article became viral overnight and today it remains the most widely quoted opinion on the subject (tens of millions of readers, and thousands of quotations), dubbed “the coronavirus must read”. Among other thoughts, Tomas Pueyo criticizes herd immunity. However, the substantive level of his article is disturbing. It does not even pretend to be scientific. The author has not performed any data crunching himself. He collected other people’s studies, and then criticized some. Worse: he did not draw most of his diagrams, but “borrowed” them from other sources. He did not do any modelling either. He used readily available models from this site by Gabriel Goh (a data scientist). What is the added value of this article? Very little, if any. The author introduces an additional “Hammer & Dance” strategy, which is a slightly modified suppression strategy from Imperial College.

Why am I quoting Tomas Pueyo? I really should not. But I have to, because as an influencer, he happened to intoxicate millions readers, explicitly criticizing the concept of herd immunity in his article. So this is what he says: herd immunity won’t work because the virus mutates. All right then, how much does it mutate? Well, red, blue and yellow. I am not joking – this is the level of the article. Tomas Pueyo is neither a virologist, nor an epidemiologist. This chart below, borrowed from Nextstrain, is his only source of information. He is not able to quote any literature telling us anything about the impact of those hypothetical mutations on human immunity, except a laconic quote from an out-of-context paper saying that RNA mutates 100x faster than DNA.

The arguments against herd immunity

That’s it for the background. Let us proceed to the known arguments against herd immunity. I do not pretend to know a lot, and I repeat this is not my field. But I examined the most commonly quoted sources, and this is what I found.

1. Tomas Pueyo’s article cannot be taken seriously. Discarded. If you are still in doubt, I recommend this piece: “I’m Not An Epidemiologist But…”: The Rise Of The Coronavirus Influencers by Ryan Roderick, BuzzFeed.

2. on 14 March, published article World Health Organisation questions UK’s ‘herd immunity’ approach to coronavirus. This article is a possible manipulation. The content says something else than the title. I did not find any evidence (Google) supporting the claim in the title.

3. Adrian Basu, a professor from the University of Canterbury, criticized the Netherlands’ decision publishing The ‘herd immunity’ route to fighting coronavirus is unethical and potentially dangerous, with the following argumentation:

a. WHO has criticized herd immunity. To my knowledge, not true. See above.

b. long-term effects of virus are not known. True.

c. With a 2.3% fatality rate and a 19% rate of severe disease, this could result in more than a million people dying. These numbers are possibly manipulated. The stated 2.3% fatality rate is an overall number including elderly people. The Dutch government is looking for volunteers in the lowest risk groups where CFR is at the level of 0.2% at maximum, and probably much lower still. Explained in my previous article.

4. Business Insider, March 20th published this: An infectious disease expert explains why herd immunity probably won’t work in the fight against coronavirus, with the following claim: 501 scientists and mathematicians had signed a letter signalling concern against herd immunity. True, however the letter referred in particular to the details of the UK government plan, while the Dutch government proposes something else. It then appears that some of the bad press associated with the term ‘herd immunity’ appears from the association with the particular (failed) implementation of that concept by the British government.

5. There is evidence, mainly from China, that some people got sick with COVID-19 twice. True. Many people seem to have developed immunity after recovery, but some have fallen sick again.

There may be more arguments. I am not an expert and I don’t pretend to be. All I want to do here is to share is my observation that many of the mainstream arguments do not hold up.

The arguments for herd immunity

1. In this article, James Paton: summarized the key argument for herd immunity in one sentence: There’s a consensus that the pandemic will only end with the establishment of so-called herd immunity. In other words, herd immunity (as the effect of either infection, or vaccination of a part of the population) is the only known mechanism to effectively stop the plague. As long as we, as a society, do not have herd immunity built in, the disease may keep coming back each time the lockdown restrictions are loosened. In effect, the lockdown may last not week but years, the effects of which we do not even want to imagine.

2. Chinese evidence of regions going back into lockdown seems to demonstrate that suppression strategy alone, without herd immunity, may be very difficult, if not impossible, to implement on a global scale, because it does not leave any defense mechanism behind. Logically, if the plague reappears in the same region, it will spread again with similar speed.

3. At the moment, everything we do is failing. The two strategies, rationally presented by Imperial College (suppression and mitigation), both have huge costs: not only social and economic, but also, as they do not warrant success, they may result in numerous deaths anyway. Most countries are trying to implement suppression. Yet, people are dying as we speak. It is obvious that we just do not know what to do. How can we afford not to try another way?

4. In addition, the probability of death for the low-risk group (healthy people below 40) is very small, as explained in my previous article. Given this, it is hard to agree with the statement that an idea of purposely infecting volunteers in some controlled environment would be unethical.

The implication of this reasoning is that there are only two ways out: vaccination or controlled infection, both resulting in herd immunity. Then the idea of waiting for the vaccine in constant lockdown carries significant cost and even greater risk, because of the uncertainty if it ever gets produced.

Logically, the idea of controlled infection seems a rational alternative, which needs to be discussed openly, without hysteria. Labelling it “controversial” adds heat but does not help.

Summing up

So here are the arguments for and the arguments against. The list is far from complete. Do I advise for any strategy (suppression, mitigation, herd immunity by infection, or waiting for the vaccine)? I am not in a position to advise. Unlike some influencers I do not feel I should speak on a subject I have no idea about.

However, I am reasonably good at working with data and information. My mission in this article is to indicate that the mainstream narration does not seem to be based on rational arguments, instead following the herd instinct: to quote whatever is trending as the most fashionable idea, eventhough those sources appear to be either flawed or purposely manipulated.

And this narration completely misses the point. Instead of wasting time on emotional discussion and low-quality sources, we should be proceeding directly to discussing the best strategy to achieve herd immunity at minimal cost. It appears the only known mechanism to protect the population from the plague. The possible strategies are numerous. This discussion, which should involve expert teams at national levels is naturally beyond the scope of this article and my knowledge.

I also feel it is irrational and highly irresponsible not to try alternatives, especially in the tragic situation Europe is now. If there are individuals and volunteers brave enough to try, they should be encouraged because in the end of the game they may save others’ lives.

Finally, I feel respect for courageous individuals who dare to oppose the herd instinct, continue their search for solution and propose unpopular ideas, in an effort to save people’s lives. While the COVID-19 influencers enjoy visibility, these brave souls often risk unjust stigmatization and ostracism.

Post Scriptum & Foot Notes

Here is Facebook page associated with this blog. Follow it to get notified about future posts. Also, your comments are welcome there.

Also see my other article: coronavirus mortality: less than we think

During discussion after the publication, I incorporated several useful comments, discarded some others. Below is the log of these edits

Incorporated changes

1. 9th April 2020: I changed significantly the summary section of the article. The original idea was to impartially collect sources for and against herd immunity, and leave the trove up to the reader to decide what makes sense. However, after analysis of the sources and early comments, it was impossible for me to remain impartial on this idea, as I found that almost all arguments against this concept were missing the point. I removed phrasing that I was not advocating herd immunity.

2. 9th April 2020: Added Herd Immunity wikipedia definition box. User’s comment made me understand that some people understand this term differently

How herd instinct hijacked herd immunity

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