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By: Deanna Altomara

Editor’s Note: This is the second in a three part series. Read the first part here and the second part here.

Quarantine has a long and complicated history, but that history has been instrumental in teaching modern-day public officials how to effectively (and ethically) prevent the spread of disease. 

   For quarantine to be helpful, three conditions must be met: 

1.  People with the infection must be quickly identified

2.  Patients must comply with quarantine guidelines

3.  The disease can be spread before symptoms are present, or in the early symptoms [9] 

Isolation and quarantine are two common public health strategies to prevent the spread of illness.  Both can be either voluntary or mandated. Isolation is used to separate ill patients from healthy people. Patients can be isolated in their homes, hospitals, or other healthcare settings. 

Quarantine, on the other hand, is used to separate people who have been exposed to a pathogen (and haven’t developed symptoms of the disease) from those who remain unexposed. It has the dual purpose of preventing the spread of disease, as well as quickly identifying disease symptoms in people who have already been exposed.[12] Quarantine can be individual or community-based, and can take place in homes or designated places, such as hotels.[10] Quarantine lasts as long as the incubation period for the disease so that people can be monitored for the development of symptoms. 

When a disease has become too widespread for individual isolation and quarantine strategies to be effective, community measures can also be taken. These measures might include education about disease identification, social distancing, the cancellation of large gatherings, and community quarantine.[10] 

On January 23, China quarantined 11 million people in Wuhan, the epicenter of COVID-19, in a move that the World Health Organization called “unprecedented in public health history.” Later, the lockdown was expanded to other cities to encompass a total of 60 million people. Foreigners were evacuated and many roads out of the city were blocked. People stayed inside their homes as much as possible, although some ventured to the outside world to visit grocery stores and restock their supplies. While deliveries of food and supplies continued, the government launched massive sanitization activities. Each person was required to report their temperature to the government on a daily basis.

Meanwhile, people who had been exposed to the virus were quarantined inside makeshift hospitals or hotels, where they were monitored for symptoms. One of these hotels collapsed, killing over 20 people. As time goes on and China’s rate of new infections drops dramatically, these restrictions are slowly being lifted. People are beginning to leave their houses and trains are starting to come back into Wuhan. If people don’t have a fever and show the proper paperwork, they can begin returning to work. One study, published in The Lancet Public Health, showed that the control strategies used in Wuhan were effective. The study also predicted that as restrictions are relaxed, the region will see a smaller, second peak in cases. By relaxing restrictions in a slow, staggered manner, the secondary peak can be further delayed.[13]

Countries like Singapore, Taiwan, and Hong Kong took quick action to protect their citizens from COVID-19. Remembering lessons learned in the 2003 SARS outbreak, Taiwan was already planning a governmental response to COVID-19 on January 20th, days before China quarantined Wuhan. By February, the three countries had placed travel restrictions on people coming from mainland China, ignoring WHO protests that travel restrictions were unnecessary. Singapore imposed rigorous testing procedures, aggressively identifying anyone who might be at risk of contracting or spreading the disease. One-party states like Singapore have been especially effective in their quick and aggressive quarantine efforts. But more liberal states can also have quarantine success; in Hong Kong, where anti-government protests have been ongoing for nearly a year, the commitment to public health remains strong. The city-state was an epicenter of the SARS outbreak, and the vivid memory is a powerful motivator for good hygiene. 

The experience of SARS has been highly influential in these countries’ response mechanisms. Since 2003, many of these countries have been preparing their public health systems for a similar situation. Emanuele Capobianco, a director at the International Federation of Red Cross and Red Crescent Societies, told TIME that these quick, effective actions show that “epidemic preparedness starts years before an outbreak.”

  Italy, on the other hand, was slow to respond to COVID-19, first quarantining towns and regions before locking down the entire country. Italy was the first Western democracy to feel the brunt of coronavirus, and was accordingly hesitant to put in quarantine measures as strict as those in place in China. But as data has shown, putting strong protective measures in place–at an early moment, and with heavy adherence–is critical for stopping the spread of the coronavirus. At this point, most Italian businesses–with the exceptions of supermarkets and pharmacies–have been closed. Weddings and funerals have been cancelled. Italians have been asked to stay home. On March 20, Italian officials tightened the restrictions by closing parks and banning activities like walking or jogging far from home. The next day, Italy announced that it would close all nonessential businesses and factory production. 

Spain and France have also ordered shutdowns, as well as cities across the world. Many US states have declared states of emergency, and on March 13 the president issued a declaration of national emergency. These announcements trigger the activation of state and federal resources, such as response plans, emergency operations centers, and the use of emergency funds. The president also activated the National Guard and ordered the Federal Emergency Management Agency (FEMA) to set up medical stations in New York, California, and Washington. On March 30, the US Navy hospital ship the USNS Comfort docked in New York City to provide support for the pandemic response. 

The United States is also striving to keep all disease control measures as fair and respectful as possible. The CDC writes:

“People under public health orders must be treated with respect, fairness, and compassion, and public health authorities should take steps to reduce the potential for stigma (e.g., through outreach to affected communities, public education campaigns). Considerable, thoughtful planning by public health authorities is needed to implement public health orders properly.  Specifically, measures must be in place to provide shelter, food, water, and other necessities for people whose movement is restricted under public health orders, and to protect their dignity and privacy.”

One analysis by bioethicist Rose Upshur theorized that quarantine is a justifiable means of disease control if it prevents the spread of disease (ie, the disease is contagious). When a quarantine is put in place, she explains, it should be as least restrictive as safely possible. There is also a societal responsibility to take care of people in quarantine, and that authorities communicate clearly and transparently why a quarantine is needed.[12] 

As the pandemic continues, officials are increasingly shifting their strategy from containment to mitigation. Containment aims to prevent spread of an illness from a small number of people into the general community. When put in place early, as they were in Hong Kong and Singapore, containment measures can effectively limit the spread of disease. As the numbers of infected cases rise, containment strategies (including isolation and quarantine) become more difficult to manage and may become less effective.[14] After a large number of people are infected, officials start focusing on community mitigation, or slowing the spread of disease.[15]

Currently, public health officials are attempting to slow the pandemic through social distancing in the community. Whereas quarantine specifically focuses on separating exposed individuals from the larger community, social distancing aims to maximize the physical distance between individuals by avoiding mass gatherings (the president has recommended that all gatherings of ten or more people be cancelled) and keeping a distance of six feet from other individuals when possible. In accordance with these guidelines, many organizations have shifted their activities online, and individuals are ordering take-out or delivery from restaurants (rather than dining in), refraining from nonessential travel, and practicing good hygiene. 

Social distancing works by flattening the disease curve. The disease curve is a chart used by epidemiologists to track how many infections occur over time. Normally, a disease curve is shaped like a rainbow, a shape called a parabola. At the beginning of the epidemic, there are only a few cases of the disease. As time passes, the number of infections rises more and more quickly. At a certain point, with the help of control measures like social distancing, the rate of new infections will slow down. Eventually, the number of new infections will peak, and finally begin to decrease.

Social distancing makes it possible to slow down the spread of disease, squashing the rainbow. The number of cases are still increasing, but at a much slower rate than would have been otherwise expected. This spreads out the time when patients get sick and come into the doctors’ office. Imagine: would it be harder for a doctor’s office to see 100 patients on a single day, or 25 patients each day for four days? Flattening the curve means that hospitals and healthcare centers are better able to handle and take care of the patients who come in. It gives healthcare centers time to get new resources (like masks) so that they don’t run out, and it also gives scientists time to develop a treatment or vaccine. It doesn’t necessarily mean that less people will get sick–although it could–but that each patient might get better care, and hopefully, a better chance of survival. A helpful simulation of the disease curve can be found here

All around the world, public health officials are working around the clock to bring an end to this pandemic. Their decisions may not always be perfect, but they are not made lightly. This pandemic is unlike any we’ve seen in modern history, and even the professionals are still learning about COVID-19. Although quarantine, isolation, and social distancing are not easy, they are critical tools to slowing down the spread of the pandemic. By following the official social distancing guidelines, every person has the power to help bring an end to the pandemic.


[1] Bennett, B. H., Parker, D. L., & Robson, M. (2008). Leprosy: steps along the journey of eradication. Public health reports (Washington, D.C. : 1974), 123(2), 198—205. 

[2] Wagner, D., Klunk, J., Harbeck, M., Devault, A., et al. (2014). Yersinia pestis and the Plague of Justinian 541-543 AD: a genomic analysis. The Lancet, 14(4), 319—326. doi: 10.3410/f.718258232.793493962

[3] Drews, K., 2013. A Brief History of Quarantine. The Virginia Tech Undergraduate Historical Review, 2. DOI: 

[4] Alfani, G., & Murphy, T. (2017). Plague and Lethal Epidemics in the Pre-Industrial World. The Journal of Economic History, 77(1), 314-343. doi:10.1017/S0022050717000092 

[5] Tognotti E. (2013). Lessons from the history of quarantine, from plague to influenza A. Emerging infectious diseases, 19(2), 254—259. 

[6] Marineli, F., Tsoucalas, G., Karamanou, M., & Androutsos, G. (2013). Mary Mallon (1869-1938) and the history of typhoid fever. Annals of Gastroenterology, 26(2), 132—134.

[7] Hatchett, R. J., Mecher, C. E., & Lipsitch, M. (2007). Public health interventions and epidemic intensity during the 1918 influenza pandemic. Proceedings of the National Academy of Sciences, 104(18), 7582—7587. doi: 10.1073/pnas.0610941104

[8] Hansen H, Groce N. Human Immunodeficiency Virus and Quarantine in Cuba. JAMA. 2003;290(21):2875. doi:10.1001/jama.290.21.2875 

[9] Schabas R. (2004). Severe acute respiratory syndrome: Did quarantine help?. The Canadian Journal of Infectious Diseases & Medical Microbiology, 15(4), 204.

[10] Wilder-Smith, A., Chiew, C. J., & Lee, V. J. (2020). Can we contain the COVID-19 outbreak with the same measures as for SARS? The Lancet Infectious Diseases. doi: 10.1016/s1473-3099(20)30129-8 

[11] Hsieh, Y.-H., King, C.-C., Chen, C. W., Ho, M.-S., Hsu, S.-B., & Wu, Y.-C. (2007). Impact of quarantine on the 2003 SARS outbreak: A retrospective modeling study. Journal of Theoretical Biology, 244(4), 729—736. doi: 10.1016/j.jtbi.2006.09.015

[12] Upshur, R. (2003). The Ethics of Quarantine. AMA Journal of Ethics, 5(11). doi: 10.1001/virtualmentor.2003.5.11.msoc1-0311

[13] Prem, K., Liu, Y., Russell, T. W., Kucharski, A. J., Eggo, R. M., Davies, N., … Hellewell, J. (2020). The effect of control strategies to reduce social mixing on outcomes of the COVID-19 epidemic in Wuhan, China: a modelling study. The Lancet Public Health. doi: 10.1016/s2468-2667(20)30073-6

[14] Institute of Medicine (US) Forum on Microbial Threats. Ethical and Legal Considerations in Mitigating Pandemic Disease: Workshop Summary. Washington (DC): National Academies Press (US); 2007. 3, Strategies for Disease Containment. Available from: 

[15] Parodi, S. M., & Liu, V. X. (2020). From Containment to Mitigation of COVID-19 in the US. JAMA. doi: 10.1001/jama.2020.3882