When does a pandemic end? To put it briefly, experts predict that “the coronavirus will likely become endemic – meaning slow, sustained transmission will persist”[8]. In these trying times, COVID-19 immunity may be exactly what the nation needs to halt rising cases, however, this term is often thrown around without a clear definition. Given the current situation, the internet is circulating with misinformation on how to become immune to the coronavirus, ranging from boosting the immune system by eating particular foods to having a lowered chance of reinfection after being infected once. In reality, none of these claims have been proven true. However, a term gaining traction in the media is herd immunity.
The concept of herd immunity is not new to the world of epidemiology. In fact, it has successfully been used to eradicate smallpox[1]. Herd immunity aims to stop disease transmission from person to person. This happens when the population immune to the virus outnumbers those still at risk for infection. Essentially, those immune serve as a shield to those not immune, keeping the virus under control and ultimately allowing the spread of disease to decline[5].
The greatest downside to herd immunity is the number of people that must become immune for it to take effect. Take measles, for example, as one of the most contagious viruses in the world, 90% of the population must be immune for the herd to be protected[1]. Herd immunity can be established with the use of vaccines, however, this is not the case everywhere. In particular, populations in areas with low vaccine coverage are more prone to outbreaks because they lack herd protection, even resulting in the 2019 measles outbreak at Disneyland[4].
The application of herd immunity on the current COVID-19 pandemic may go one of two ways: vaccination or natural infection[6]. These two approaches are not separate but rather go hand in hand in the fight against the virus. Developing a vaccine is easily the safest and fastest method in controlling the outbreak, but, it may never completely eradicate it[1]. According to Amber D’Souza, a professor of epidemiology from Johns Hopkins, it is not inevitable that everyone gets this infection. Instead, she states that the nation must remain hopeful that a vaccine will be developed in order to get prevention that way[1].
A vaccine works by training the immune system to create antibodies, proteins that fight disease in the same way the body would if it were actually exposed to the virus. Using a vaccine, one may reap the benefits of being protected from the disease and being unable to pass it on without ever getting sick in the first place. With herd immunity, since the majority of the population are immune, they are able to protect the more vulnerable groups such as children, elders, and those with underlying health conditions that cannot get vaccinated[9].
In the absence of a widely-used vaccine against COVID-19, the world must now consider the route of natural infection. Although a viable option in theory, it is quite problematic in practice. The World Health Organization (WHO) states that “herd immunity is achieved by protecting people from a virus, not by exposing them to it”[9]. The answer to the COVID-19 pandemic can not be herd immunity because of the ramifications from rising cases and the many unknown variables surrounding its immunity[2].
If everyone stopped social distancing measures for the sake of getting infected to “get it over with”, hospitals would be overwhelmed with patients and as a result, increase the total number of deaths[3]. This solution is simply not feasible with the severity of SARS-CoV-2, having a death rate that is 10% higher than the flu[1]. Since COVID-19 is highly contagious, “experts estimate that 70% of the U.S. population — more than 200 million people — would have to recover to halt the epidemic”[6].
According to WHO, once infected, patients develop an immune response within the first few weeks[9]. However, it is too early to tell exactly what the long-term health impacts are after contracting the virus. Experts are still exploring these effects but are unsure about the factors that affect immunity such as its strength, its duration, and how it differs depending on the individual and their health conditions [9]. Research also suggests that it is possible to be reinfected by the same coronavirus after a certain period of time and further testing is needed to determine the protective effects of antibodies from those who have been infected[6].
Under the guidance of the WHO, the United Nations is also urging that “[stemming the COVID-19 pandemic with] ‘herd immunity’ is ‘unethical’ and ‘not an option’ countries should pursue to defeat the virus”[7]. With that in mind, please take the necessary precautions to be safe: wear a mask, social distance, and sanitize hands. By working together, let’s transform “flattening the curve” into a reality.
References
[1]D’Souza, G., Dowdy, D. (2020). What is Herd Immunity and How Can We Achieve It With COVID-19?. Johns Hopkins Bloomberg School of Public Health. https://www.jhsph.edu/covid-19/articles/achieving-herd-immunity-with-covid19.html
[2]Feinberg, J., File, T. (2020). “Herd Immunity” is Not an Answer to a Pandemic. Infectious Diseases Society of America. https://www.idsociety.org/news--publications-new/articles/2020/herd-immunity-is-not-an-answer-to-a-pandemic
[3]Hinshaw, D. (2020). Herd immunity and the Great Barrington Declaration. Government of Alberta. https://www.alberta.ca/herd-immunity-and-the-great-barrington-declaration.aspx
[4]Krakow, M. (2019). Measles: A tourist infected with measles visited Disneyland and other Southern California hot spots in mid-August. Washington Post. https://www.washingtonpost.com/health/2019/08/24/tourist-infected-with-measles-visited-disneyland-other-southern-california-hotspots-mid-august/
[5]Labos, C. (2020). Herd Immunity Against COVID-19? There's a Big Catch. McGill Office for Science and Society. https://www.mcgill.ca/oss/article/covid-19/herd-immunity-against-covid-19-theres-big-catch
[6]Mayo Clinic. (2020). Herd immunity and COVID-19 (coronavirus): What you need to know. https://www.mayoclinic.org/diseases-conditions/coronavirus/in-depth/herd-immunity-and-coronavirus/art-20486808
[7]UN News. (2020). Herd immunity, an ‘unethical’ COVID-19 strategy, Tedros warns policymakers. https://news.un.org/en/story/2020/10/1075232
[8]Varlik, N. (2020). When Will The Pandemic End? If We Look at History, The Answer Is Not So Simple. Science Alert. https://www.sciencealert.com/history-tells-us-the-future-of-the-coronavirus-pandemic-has-no-end-date
[9]World Health Organization (WHO). (2020). Coronavirus disease (COVID-19): Herd immunity, lockdowns and COVID-19. https://www.who.int/news-room/q-a-detail/herd-immunity-lockdowns-and-covid-19
Written and graphics by Lananh Vo
Edited by Rachel Glantzberg
Group advised by Ruhi Sahu