by Jianli Yang
When the COVID-19 outbreak first occurred in Wuhan, China, few people thought that this epidemic would have such a significant impact in the West. This is certainly related to the fact China covered up the outbreak and misled the world in its early stages. It also has to do with misinformation and bad advice from the World Health Organization (WHO).[1] However, these facts do not constitute the entire cause; some responsibility must also be borne by each country itself. With the high frequency of international travel in the modern era, it would have been difficult for the epidemic not to spread at all to other countries, unless Wuhan completely controlled the virus’s outflow from the earliest stages of detection. In January, novel coronavirus cases were discovered in both Europe and North America. Early public opinion was focused primarily on Italy. Although the epidemic had already reached other countries, people simply didn’t pay sufficient attention to this reality. This should firstly be attributed to the missteps of governments in handling – and their contemptuous attitude towards – the epidemic. For example, even in late February, U.S. President Donald Trump still claimed that the epidemic was “under control.”[2] As another example, when the international community was just recognizing the presence of a COVID-19 epidemic in the United Kingdom, the epidemic was already ravaging the country.
Among the multiple reasons why the epidemic is still so prevalent is the profound effect of the so-called theory of “herd immunity” on the policy-making mindsets of governments around the world. Although Sweden’s radical “herd immunity” strategy failed and few officials continue to talk publicly about herd immunity, the theory still has some traction, which has resulted in the deployment of ineffective epidemic prevention and control strategies in many countries.
The “herd immunity” theory is based on an understanding of the concept of herd immunity, also known as “community immunity” or “population immunity.” The phenomenon of herd immunity means that when an infectious disease strikes, if a certain percentage of the population develops immunity due being infected or receiving a vaccine, this erects a barrier to the spread of the virus, thereby greatly reducing the chance of infection from person to person and stopping the pathogen’s further spread. Judging from the vaccination statistics for epidemics like diphtheria, measles, mumps, whooping cough, polio, and smallpox, a minimum threshold of at least 75 percent must be reached in order to achieve herd immunity.
This understanding of herd immunity is undoubtedly correct, but the resulting “herd immunity theory” and “herd immunity strategy” are full of uncertainties and risks. If no vaccine exists for a specific infectious disease, then the idea of achieving herd immunity is merely a hypothesis.
Unfortunately, the governments of some countries have recklessly and irresponsibly proclaimed that they will use the herd immunity effect to deal with COVID-19, which, in comparison to other infectious diseases, shows high transmissibility and infectivity, but a low mortality rate. For example, Sir Patrick Vallance, chief scientific adviser to the Government of the United Kingdom, stated: “What you can’t do is suppress this thing completely, and what you shouldn’t do is suppress it completely.”[3] According to Vallance, about 60 to 70 percent of people would need to be infected and recover in order to achieve herd immunity in the U.K. In addition, Chris Whitty, the U.K. government’s chief medical adviser, said that it would be neither possible nor desirable to protect everyone against the virus, because people need to gain some immunity in order to protect themselves in the future.
Due to the guidance of these “herd immunity” proponents, British Prime Minister Boris Johnson said after the outbreak had reached a broad scale that the government’s plan was to delay the virus’s spread and extend the peak period in order to minimize its impact. He also said that schools would not be closed[4] and that large gatherings would not be prohibited[5], since doing so would have little effect on controlling the spread of the virus. Later, Johnson himself tested positive for COVID-19 and was admitted to the intensive care unit of St Thomas’ Hospital. His infection was so severe that he nearly died from it. Since then, herd immunity is rarely mentioned in the United Kingdom. However, many countries (including the U.K.) still use “herd immunity” theory to varying degrees as the basis for responding to the epidemic. This is because, as Vallance said, the core tenet of “herd immunity” theory is: “What you can’t do is suppress this thing completely, and what you shouldn’t do is suppress it completely.” This view completely ignores the fact that the economic, medical, technological, and informational conditions of modern society make it possible to suppress the virus’s spread. It also ignores the work of 29 countries around the world to completely eradicate SARS-CoV-1 in 2003–2004.
It is uncertain whether a COVID-19 vaccine will be successfully developed. At a minimum, a vaccine will not be part of epidemic prevention and control work in the short term. Herd immunity proponents adhere to the belief that more than 60 percent of the population will eventually be infected with the novel coronavirus. Based on this view, in the absence of any understanding of the characteristics of COVID-19, U.K. chief scientific adviser Patrick Vallance said recklessly: “If you completely locked down absolutely everything, probably for a period of four months or more, then you would suppress this virus. All of the evidence suggests that when you do that, it all comes back again. The other part of this is to make sure that we don’t end up with a sudden peak again in the winter, which is even larger and causes even more problems.”[6] What Vallance meant was that even if infections can be avoided now, ultimately, more than 60 percent of the population will still be infected. And if infections occur during the peak period of influenza, then the healthcare system will be overburdened. Vallance’s unstated conclusion, of course, is that it is better to have more infections in advance and to ensure that there are no concentrated outbreaks, so as to reduce the number of deaths.
This is what we hear from all proponents of “herd immunity.” They are always talking about “flattening the curve,” protecting the elderly and people with underlying diseases, avoiding the collapse of the healthcare system, and so on. Of course, all of these things need to be done. But in the view of “herd immunity” theorists, this is seemingly all that needs to be done. After all, as long as the healthcare system doesn’t collapse, why worry about infection? It was on the basis of this defective logic that British PM Johnson talked about “delaying the spread of the virus” and “prolonging the peak period of infection.” People cannot help but ask: If the government has the ability to “delay” the spread of COVID-19, then why allow the existence of a “peak” in the first place? And why extend the peak’s duration?
The subtext is that we cannot allow too many people to get infected all at once, because that would overstrain the healthcare system, but there is no need to suppress the virus within a short period of time.
However, the facts once again demonstrate that it is feasible to reduce economic losses and the loss of life by suppressing transmission of the virus. In contrast, the “herd immunity” strategy is completely wrong – at least with regard to the COVID-19 pandemic. Wuhan and Taiwan, despite having different political systems, have both basically halted their respective COVID-19 epidemics by suppressing the virus. Some people think that there will be a second wave of the epidemic in the autumn and winter, but so what? Taiwan’s experience in battling the epidemic shows that even if the virus makes a comeback, as long as epidemic prevention and control work is done properly from the beginning to suppress the virus, no citywide lockdowns or works stoppages are necessary to keep the epidemic from regaining a stronghold. The only reason for the lockdowns in Wuhan (and other cities in Hubei province) was the failure of China’s initial epidemic prevention efforts. As for China’s other provinces, as long as (1) they followed Taiwan’s approach, (2) there were qualified and responsible epidemic prevention teams in place, and (3) the authorities transparently appealed to the public to cooperate, then there would be no need for lockdowns – and it still might be possible to halt the epidemic in its tracks.
In contrast, calls for herd immunity have proven to be nothing but “armchair strategizing.” Taking New York State, one of the most severely affected areas in the world, as an example, as of April 2020, only 13.9 percent[7] of the state’s population had coronavirus antibodies – far from the threshold needed for herd immunity. Besides, some people think that even if 60 percent of the population develops immunity after being infected, it might still be insufficient to achieve a herd immunity effect. According to research conducted by the Los Alamos National Laboratory, at least 82 percent[8] of the population would have to be immune in order to stop the virus from further spreading. According to the Iranian government, about one-third of people in Iran have antibodies, far short of the 60 percent threshold. Sweden once optimistically claimed that herd immunity could be achieved by April, later revised to June. But judging from the number of new daily cases, Sweden has been unable to achieve this threshold. On the contrary, because of the severity of the epidemic and high death rate in Sweden, the European Union instituted a ban on travel via Sweden,[9] making Sweden a model of how not to respond to the epidemic.
In addition, the immunity developed after an infection may be temporary. This means that some people’s post-infection immunity won’t last very long, and these people may be re-infected. There are already cases that prove this.[10] Furthermore, given the possibility of viral mutation, even if 60 percent of the population is immune, they still might have developed immunity at different times. In that case, even if 100 percent of the population has been infected, what would the use be? In large urban settings, hoping that enough people will be infected so as to achieve herd immunity is simply impractical. It may be possible to achieve herd immunity in a small gated community, but on a metropolitan or national scale, it is impossible, at least with respect to COVID-19. Since it takes times for the virus to spread, and since most people instinctively take steps to prevent themselves from being infected, the virus is unable to infect the vast majority of people within a short period of time.
Some people think that the 1918 Spanish flu pandemic was the result of attempts to pursue herd immunity. However, this claim remains inconclusive as there is insufficient evidence to support it. Zhang Wenhong, an epidemic prevention expert based in Shanghai, believes that “there is no precedent in human history for overcoming an epidemic through a laissez-faire herd immunity strategy.”[11]
It is one thing to acknowledge the existence of herd immunity, but using herd immunity as an epidemic prevention strategy is another matter. Relying on herd immunity from the outset to contain or control an outbreak denies the possibility of humans suppressing the virus (in this case, SARS-CoV-2) to eliminate the infectious disease that it causes (in this case, coronavirus disease 2019, aka COVID-19). Even if the virus cannot be suppressed, in a worst-case scenario, the “hope” of herd immunity itself diminishes the perceived need to minimize infections and buy time to develop a vaccine. Furthermore, with viral mutation, there is a chance that the pathogen’s virility and resultant fatality rate will gradually decrease over time, so even if the epidemic cannot be controlled, we must try to delay new cases of infection as much as possible.
The course of an epidemic cannot be shifted by human will. Once a period of high incidence occurs, bringing the numbers down is no easy task. For example, since the beginning of July, the number of new confirmed cases of COVID-19 in Florida has approached or exceeded 10,000 cases per day, with no reversal of this trend in sight. No one dares to say, with confidence, that the state’s healthcare system won’t collapse. Every new case means an additional source of infection and an increase in the difficulty required to bring the epidemic under control. Therefore, the goal of epidemic prevention and control work must always be to avoid new infections, rather than to “flatten the curve.”
Every proposed course of action – including flattening the curve, protecting the elderly and people with underlying diseases, and avoiding the collapse of the healthcare system – that is underpinned by “herd immunity” theory, as opposed to calling for vigorously suppressing the virus, will inescapably shift towards the regressive view that achieving herd immunity is the only way to control the epidemic.
Even if the virus cannot be fully eradicated, striving to suppress its transmission is still advantageous. After a period of strong and effective epidemic control, such that new cases are limited to small numbers or certain regions, resulting in a decline of infection sources and the decreased spread of the pathogen, locked-down cities and states can be reopened. At that point, through the efforts of qualified and responsible epidemic control teams, and through the adoption of multiple epidemic control measures that have a lesser impact on people’s lives, epidemic control results like those of Taiwan[12] can gradually be attained – or we can wait for a vaccine when the number of new daily cases is at a very low level. Only then can we talk about herd immunity.
It bears repeating: If we discount the potential development of a vaccine, it makes no sense to talk about herd immunity, at least with respect to COVID-19. Even if more than 60 percent of the population is eventually infected, herd immunity won’t really be achieved; such a high level of infection would merely prolong the epidemic and the work being done to control it. We mustn’t let our “herd immunity” illusions become an excuse for responding to the epidemic in a passive rather than proactive manner.
The COVID-19 epidemic isn’t just an issue of virology and medicine. It is also a major economic and social issue. As long as there is a high incidence of new cases, society will be unable to reopen, and a protracted epidemic will result in immeasurable economic losses. Given this fact, the confidence of “herd immunity” proponents in the early stages of the epidemic was actually quite reckless and irresponsible. Swedish immunologist Dr. Cecilia Söderberg-Nauclér raised the question bluntly: “No one has tried this route, so why should we test it first in Sweden, without informed consent?”[13]
The number of new infections in Sweden and the U.K. remains relatively high. The failed epidemic control policies of these two countries has caused herd immunity proponents to lose confidence and stop talking, at least publicly, about their so-called “herd immunization” strategy. However, herd immunity is still part of the explicit or implicit theoretical foundations of the epidemic control strategies of many countries and many people still believe in this theory. With the promising work that is being done to research and develop a vaccine against COVID-19, it is fine to hope that a vaccine will alter the passive and reactive (as opposed to proactive) state of epidemic control work. However, it will take time for a vaccine to be approved and become widely available on the market, and the effectiveness of any potential vaccine remains uncertain. It is also uncertain how long it would take to mass-produce and promote a COVID-19 vaccine. The best prevention strategy is still to suppress transmission of the virus and strive to vastly reduce the number of new cases, rather than claiming that everything will be fine as long as pressure on the healthcare system is alleviated. In some regions where the local medical system has not yet felt too much pressure, if the epidemic escalates and cannot be sufficiently suppressed, a major outbreak could occur at any time. For the government, the earlier we adopt epidemic prevention and control measures, the smaller the resultant losses will be. We must act now, and not wait for another major outbreak to be galvanized into anxious action.
In order to reduce economic losses and the loss of life, epidemic prevention and control work must be conducted with a sense of utmost urgency. As the Danish Minister of Health and Prevention remarked: “We have no evidence that everything we do is effective, but we would rather do too much today than regret doing too little in three weeks.”[14] Due to the characteristics of infectious diseases, epidemic prevention and control work requires extensive unified action. There is no substitute for the role of the central or federal government. Our ability to achieve a sustained economic recovery hinges on the timeliness and efficacy of our epidemic prevention and control work. This will require the collective efforts of governments at all levels, as well as experts, the media, social institutions, and the public.
We must not place our blind credence in the COVID-19 “herd immunity” hypothesis. We must not be careless or negligent just because we ourselves are in good health and the fatality rate remains low (compared to other infectious diseases). After all, many young people have lost their lives or become seriously ill after being infected with SARS-CoV-2. Besides, in an epidemic, anyone can be infected or infect others. Epidemic prevention and control measures aren’t only a matter of self-responsibility, but also of our responsibility to others. It will never be too late. Taking substantive and meaningful steps to curb the COVID-19 epidemic is the responsibility of every citizen.
[1] “Coronavirus: Trump Accuses WHO of Being a ‘Puppet of China’.” BBC News, BBC, 19 May 2020, www.bbc.com/news/health-52679329.
[2] Greenburg, Jon. “’We Have It Totally under Control.’ A Timeline of President Donald Trump’s Response to the Coronavirus Pandemic.” Poynter, 24 Mar. 2020, www.poynter.org/fact-checking/2020/we-have-it-totally-under-control-a-timeline-of-president-donald-trumps-response-to-the-coronavirus-pandemic/.
[3] Sparrow, Andrew. “Containment of Virus ‘Extremely Unlikely to Work on Its Own’, Says Boris Johnson – as It Happened.” The Guardian, Guardian News and Media, 9 Mar. 2020, www.theguardian.com/politics/live/2020/mar/09/boris-johnson-cobra-labour-trevor-phillips-says-his-suspension-by-labour-suggests-party-turning-into-brutish-authoritarian-cult-live-news.
[4] Hoare, Callum. “Coronavirus UK: Plan for Schools to ‘Remain Open until JULY’ Exposed as Virus Peak Looms.” Express.co.uk, Express.co.uk, 13 Mar. 2020, www.express.co.uk/news/uk/1254697/coronavirus-uk-schools-closed-easter-holidays-boris-johnson-cobra-meeting-spt.
[5] Biggs, Stuart. “UK Coronavirus News: Boris Johnson Sets on Path on Response.” Bloomberg.com, Bloomberg, 9 Mar. 2020, bloomberg.com/news/articles/2020-03-09/johnson-s-faith-in-coronavirus-advice-sets-u-k-down-own-path.
[6] Cecil, NIcholas, and Joe Murphy. “Coronavirus Lockdown ‘Risks Even More Deaths’, Warns Top UK Scientist.” Evening Standard, 5 May 2020, www.standard.co.uk/news/uk/uk-scientist-warns-coronavirus-lockdown-risks-more-deaths-a4386661.html.
[7] “Coronavirus Survey Reveals 13.9% In New York Have COVID-19 Antibodies, Cuomo Says.” CBS New York, 23 Apr. 2020, newyork.cbslocal.com/2020/04/23/coronavirus-survey-reveals-13-9-percent-in-new-york-have-covid-19-antibodies-cuomo-says/.
[8] “Coronavirus May Spread Twice as Fast as Initial Thought, Study Says.” The Business Standard, 13 Apr. 2020, tbsnews.net/coronavirus-chronicle/coronavirus-may-spread-twice-fast-initial-thought-study-says-68692.
[9] “Temporary Ban on Travel to the EU via Sweden Due to COVID-19.” Government Offices of Sweden, Ministry of Justice, 18 Mar. 2020, www.government.se/press-releases/2020/03/temporary-ban-on-travel-to-sweden-due-to-covid-19/.
[10] Roy, Sayak. “COVID-19 Reinfection: Myth or Truth?” Sn Comprehensive Clinical Medicine, Springer International Publishing, 29 May 2020, www.ncbi.nlm.nih.gov/pmc/articles/PMC7255905/.
[11] “张文宏：靠‘群体免疫’抗击新冠病毒？想都不要想！特朗普称美国新增病例峰值已过；美军称巡逻机在地中海遭到俄军机拦截.” 微博, 每日经济新闻, 15 Apr. 2020, m.weibo.cn/status/4494252836422288.
[12] Chen, Lanhee. “The US Has a Lot to Learn from Taiwan’s Covid Fight.” CNN, 10 July 2020, www.cnn.com/2020/07/10/opinions/taiwan-covid-19-lesson-united-states-chen/index.html.
[13] Ahlander, Johan. “Sweden’s Liberal Pandemic Strategy Questioned as Stockholm Death Toll Mounts.” Reuters, 4 Apr. 2020, www.reuters.com/article/us-health-coronavirus-sweden/swedens-liberal-pandemic-strategy-questioned-as-stockholm-death-toll-mounts-idUSKBN21L23R.
[14] 环球时报 . “瑞典首都‘群体免疫’下月见效？俄媒：民众成了小白鼠.” 文化艺术网, 28 Apr. 2020, www.whysw.org/m/view.php?aid=22623.