How History of Medicine Helps Us Understand COVID-19 Challenges

History has informed much of the social and political response to the coronavirus disease 2019 (COVID-19) pandemic, most notably in decisions about having people shelter in place and donning masks, as well as when and how to ease quarantine restrictions. When confronting the uncertainty of controlling the spread of a novel disease, these actions rely on information about the management of past pandemics to estimate their potential effectiveness as public health interventions. For example, during the current COVID-19 pandemic, public health decision makers in San Francisco reflected on the 1918-1919 influenza epidemic in the city, which offered evidence of the risks of relaxing measures too soon, after an apparent flattening of the curve, offering insight into the limits of public tolerance for social interventions and the political and economic pressures to return to normal.¹ In addition, history exposes long-term structural inequities that create barriers to health care access, foster community distrust in public health ordinances, and result in worse health outcomes for vulnerable populations (eg, people who are low income, African American, and older) compared with non-vulnerable populations (eg, people who are high income, White, and younger). In this commentary, we examine the role that historical investigation plays in rationalizing public health interventions and helping to understand the public response to pandemic controls.

On March 19, 2020, when California Governor Gavin Newsom issued an executive order for all Californians to shelter in place,² historical investigations of past pandemics supported the effectiveness of social distancing as an approach to slow the transmission of communicable diseases. For example, several studies examined historical data from the 1918-1919 influenza pandemic in the United States to understand how nonpharmaceutical interventions slowed the spread of the virus and reduced mortality rates.^3-5 Using large historical data sets,^6,7 these studies conducted multicity statistical analysis in the United States across a multiweek period to document the urban experience with social distancing, the isolation of sick patients, and mask ordinances. The studies found that these measures, when combined, enacted early, and sustained, improved public health and safety. The studies also suggest that late interventions, by contrast, almost always yielded worse outcomes.

These conclusions affirmed similar pandemic preparedness recommendations made in 2006 by the World Health Organization⁸ and the Centers for Disease Control and Prevention.⁹ These studies were likewise informed by historical analysis, including scholarship on worldwide quarantine actions in 1918,¹⁰ a World Health Organization expert review of the 1957 influenza pandemic,¹¹ and the severe acute respiratory syndrome coronavirus (SARS-CoV) epidemic of 2003.¹² Reviews of the impact of school closures¹³ in Hong Kong and social distancing¹⁴ internationally during the influenza H1N1 outbreak of 2009 suggested the effectiveness of these measures in buying time to manage the spread of disease and reduce burden on the health care sector. However, the reviews also reveal the risks of causing public distress and economic havoc. The historical record says that public health policy involving social distancing is more effective than voluntary isolation because infections can spread through viral shedding⁸ days before symptoms of illness appear. If transmission occurs during the asymptomatic incubation period, past experience suggests that the often-touted alternative of health screening and case-patient isolation will have diminished impact.

If history provides insight into the effectiveness of quickly implementing social distancing orders, what lessons are learned about easing restrictions or ending quarantine? While saluting the success of the orders put in place in San Francisco—the first city in the United States to enact shelter-in-place orders during COVID-19—Mayor London Breed cautioned against celebrating too soon. During an interview with MSNBC host Chris Hayes, she said, “Well, I do think it’s important that we also remind people of history. The Spanish flu in San Francisco in 1918 when the city had a big party and threw away their masks and celebrated, and then a few days later, two thousand people died.”¹

Mayor Breed was referring to a moment in late November 1918 when San Francisco was released from an ordinance requiring everyone to wear cloth face masks in public. The Red Cross had claimed that masks were “99% proof against influenza” and that wearing one was “a patriotic duty.”¹⁵ Removing them was the last step in returning the city to normal, after a month-long intervention taken by Mayor James Rolph that also closed schools, churches, bars, restaurants, sporting events, and public gatherings. According to the San Francisco health officer at that time, Dr William Hassler, their action to mask the public—which was taken early and emulated by many other US cities—was successful at stopping the spread of influenza.¹⁶ After a whistle blast at noon on November 21, 1918, the masks were allowed to come off and “the sidewalks and runnels were strewn with the relics of a tortuous month.”¹⁷

Although Mayor Breed’s reference to 2000 people dying a few days later was historically inaccurate, her valid point was that the decision to unmask the public and reopen businesses so quickly in 1918 was premature. During the first week of December, 722 new influenza cases were reported in the city. By the end of the following week, an additional 1517 cases had appeared.¹⁸ Hassler immediately called for a reinstatement of the public health measures, including masks, but the business community pushed back strongly, citing the economic damage as the holiday season approached. Mayor Rolph opted for a public health announcement rather than a law, but cases continued to climb. When more than 600 deaths were reported in 1 day in mid-January, the city once again required people to don masks. In response, a group of San Francisco residents formed the Anti-Mask League to stage protests against what they called “insanitary and useless masks.”¹⁹

Recent analysis suggests that this group may have been politically motivated, intent on discrediting a mayor against whom these people repeatedly campaigned.²⁰ But to justify its platform, the group seized upon conflicting opinions on how best to maintain a salubrious environment. The group cited long-standing health advice that “fresh air is the best preventive and cure” for disease, arguing that masks instead created a repository of foul air. More problematically, the American Public Health Association discussed the issue at its annual meeting in December 1918 and concluded that “the beneficial results consequent on the enforced wearing of masks by the entire population at all times was contradictory.”²¹ The question was not whether masks had any value in the prophylaxis of influenza, but whether such a sweeping policy of social control could be enforced in a way to have overall beneficial effect. Similar to concerns expressed today, delegates of the American Public Health Association questioned whether people would wear masks correctly and whether the public would understand the mask’s function of preventing the outward spread of germs rather than filtering the air they inhale. As the Oakland, California, public health officer Fred Morse stated at the time, it should be considered less a “mask ordinance” and more “an anti-expectorating ordinance.”²² One writer to the San Francisco Chronicle summed the frustration by stating, “What doctors don’t know about this epidemic of influenza would fill a decent-sized library. And yet they have the ‘gall’ to force us to wear masks as a preventive, when no two authorities in the United States are agreed as to the cause, let alone the prevention or cure of the disease.”²³

According to newspaper reports, the largest protest drew “several hundred opponents of the masking ordinance” to a meeting of the San Francisco board of supervisors, who once again were considering the repeal of mandatory masking. However, besides the Anti-Mask League, the movement now included “the hotel men, the Chamber of Commerce, and the Merchants’ Association,” all wanting the masks to disappear.²⁴ Political pressure was coming from all sides, and on February 1, 1919, exactly 2 weeks after the renewed directive went into effect, Mayor Rolph signed a proclamation nullifying the ordinance.²⁵ Although Dr Hassler stated that “the influenza situation had improved to such an extent” that he approved the mayor’s decision, the cases did not disappear; dozens of new reports each week emerged until July but with no major new spike.²⁶

Watching numbers rise and fall, battling political biases, sifting through conflicting information, trying to preserve the public trust, and addressing economic pressures all weighed on the decisions about how to manage the city in 1918-1919, and they seem to resonate with discussions today. Some studies²⁷ question the scientific validity of using historical narrative in health policies that are put into effect in times of pandemics, measuring the evidence against the gold standard of controlled clinical trials. But it is clear that in times of emergency, like the present, historical insights²⁸ help us to estimate the potential health benefits of critical actions and have been used to guide present social policies advocated by the Centers for Disease Control and Prevention²⁹ to help control COVID-19.

History has its evidentiary limits, and the present has many characteristics that separate it qualitatively from the past, placing limits on direct comparison. Advances during the last century in biomedical technology, improved ability to manage comorbidities, advanced communication, and modes of surveillance all provide an advantage to planning public health interventions. However, as we experience the COVID-19 pandemic, our technologies and tools—whether respirators, nasal swabs, or personal protective equipment—may not be stockpiled in sufficient quantities to help us mitigate disaster. Returning to techniques used a hundred years ago, such as remaining socially distant and sewing cotton masks, provides a well-tested fallback for emergency measures.³⁰

It is also true that history does not predict the future. As public health experts and policy makers struggle to reduce the impact of a novel virus, which medical science has been unable to predict or control with existing data, history becomes a valuable resource for perspective on the scope of the problem we face. The problem of imposing public health measures to control the spread of disease extends to areas where past interventions and outreach failed to provide health care protections to underserved communities. In San Francisco in 1918, for example, a discussion of quarantine measures was likely to evoke fear and distrust among the Chinese community, which at the beginning of the century was subjected to cordon sanitaire to eradicate bubonic plague.³¹ Historical review³¹ shows that the action to impose a cordon sanitaire was driven by racism and discrimination. As a recent comparison of the impact of COVID-19 and the 1918 influenza pandemic shows, underserved communities are disproportionately affected in terms of morbidity and mortality.³² Although history never repeats itself exactly, historical investigation provides clear evidence that structural inequalities and barriers to health care have persisted, a lesson that demands new approaches to problem solving.³³

During a pandemic crisis, the lessons history offers reflect who is seeking guidance. For a general public, learning about the 1918-1919 pandemic may help people understand the potential for recurring peaks of cases and the longevity of flattened curves. For advocates of equity and inclusion in health care, historical analysis of the conditions that increase the risks of vulnerable populations provides data for directing resources to overcome disparities. Politicians may learn about inevitable pressures to address the economic impact of social distancing, public impatience with government interventions, and quarantine fatigue leading to protests. Epidemiologists may be interested in examining the correlation between the speed of implementing policy decisions and the risks of ending public health interventions too soon, a circumstance clearly illustrated in San Francisco in 1918. Although history informs all these perspectives, it is also important to note that “one virus’s pattern is not a prediction.”³⁴ The novelty of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) renders parallels with the past impossible. Nevertheless, whenever we tread on uncertain ground and enter new phases of hopeful recovery, all stakeholders can draw on a wealth of historical data that teach us to proceed with caution and sensitivity to the needs of different communities.

ORCID iD

Brian Dolan, PhD https://orcid.org/0000-0002-7935-8915