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A Commentary on the JAMA Study's Interpretation of the Influenza Experiences in New York City and Chicago, 1918-19
Introduction
On August 8, 2007, we published our research on the implementation and outcomes of NPI in 43 U.S. cities during the influenza pandemic, from September 8, 1918 to February 22, 1919, in the Journal of the American Medical Association (JAMA). We found that those cities that implemented non-pharmaceutical interventions [NPI] in an early, sustained, and layered manner generally fared better than those that did not, in terms of time to peak and total mortality burden. This study is the most comprehensive, retrospective, peer-reviewed analysis of the application of NPI to mitigate influenza pandemics in print. 1
Based on our historical and statistical analysis we concluded that NPI “can play a critical role in mitigating the consequences of future severe influenza pandemics (category 4 and 5) and should be considered for inclusion in contemporary planning efforts as companion measures to developing effective vaccines and medications for prophylaxis and treatment.” Our study, however, is only one of several historical, epidemiological, or mathematical modeling peer-reviewed studies contributing to and supporting the community mitigation strategies proposed by the U.S. Centers for Disease Control and Prevention. 2
Recently, assertions were made on the internet challenging our interpretation of the historical record of New York City and Chicago during the 1918-19 pandemic. We therefore offer the following additional evidence to support our conclusion, and invite you to review the primary source documents linked to the endnotes of this commentary.
Among the assertions made are claims that our interpretation of data in New York City and Chicago is incorrect, and that such “putative errors” are sufficient to drop the findings below statistical significance. This assertion, however, ignores our approach in doing robust statistical analysis using a comprehensive dataset. Our comprehensive analysis of all 43 cities across the United States is far more robust than a disputed data point for a single city. The city-specific interpretations appear below.
New York City
The Uses of Quarantine and Isolation in New York, circa 1918
In the 21st century, most people understand quarantine and isolation protocols as legal orders accompanied by a clear paper trail of official documentation. 3 However, in New York City (as well as the rest of the United States) in 1918, quarantine was a complex concept with multiple meanings and uses. These included voluntary and enforced isolation of the ill in city-run contagious disease hospitals as well as general hospitals and medical facilities serving as de facto isolation sites, home quarantine of the contacts of those suspected of being ill, placard quarantine of places where disease was discovered, confinement of children to homes, and isolations or quarantines ordered by private physicians, as well as the enforced removal of recalcitrant individuals to the State quarantine station in New York Harbor or city lazaretto in the East River, modified sanitary cordons, port closures, and travel restrictions at railway terminals. To make matters even more complex, the two terms, isolation and quarantine, were often used interchangeably in 1918, and the extant documentary evidence is often far more nuanced than an inventory of the number of cases, deaths, or modern-era legal quarantine documents. 4
There is, unfortunately, no way to quantify with exact precision the level of public compliance with any of the NPI in any of the 43 cities in our study, nor do we make claims to such precision in the paper. When studying the broader context of epidemics of this era, however, the historical record suggests that when such public health orders were enacted, they were taken rather seriously, albeit not universally.
What we can quantify, using the wide body of primary historical sources, reports and newspaper accounts we were able to gather, is a determination of the dates when such NPI orders (e.g., quarantine and isolation, school closure, and various public gathering bans) were activated and deactivated in each city as well as their weekly excess influenza and pneumonia mortality rates; using that data, we statistically measured the epidemiological associations between overall performance of the 43 cities and their weekly excess influenza and pneumonia mortality.
The Documentary Evidence of New York City's Quarantine and Isolation Efforts
Despite claims to the contrary, there is abundant documentary evidence that New York City ordered and implemented isolation and quarantine protocols against influenza during the fall of 1918.
In order to understand the policies of a municipal health department during this era, it is essential to consult the gold standard of primary sources, specifically, the Weekly Minutes of the Department of Health, and, because public health administration is inextricably connected to legal frameworks, the city’s Sanitary Code.
With respect to New York City’s efforts, on September 17, 1918, as recorded in the minutes of its weekly meeting, the Board of the city’s Department of Health adopted a resolution making cases of influenza as well as acute lobar and bronchial pneumonia reportable, placing these diseases in the same category of risk as cholera, smallpox and plague, among other highly contagious diseases. The Board also resolved to amend Section 86 of the Sanitary Code to reflect this important change. 5 Under Section 87 of the Sanitary Code, it was the duty of “every person having knowledge” of a case of apparently or presumably infectious disease to report it to the Department of Health. Furthermore, and most important, Section 89 required the isolation and quarantine of cases and suspects of those infectious reportable diseases listed in Section 86. Finally, Section 90 required that physicians report deaths from infectious diseases. Most pertinent, by amending Section 86 to include influenza and pneumonia the Board of Health not only made these diseases reportable, but actionable as well. 6
The next day, September 18, the Department of Health sent a letter to all resident physicians, alerting them that influenza, acute lobar pneumonia, and bronchial pneumonia had been made reportable diseases. The letter reminded physicians of their legal responsibility to isolate and quarantine influenza and pneumonia cases. 7
In other words, a quarantine and isolation order was an act that every physician in the city, whether they were connected with the public health department or not, was empowered to order and execute; in the event a private citizen suspected influenza, he or she, too, had the legal responsibility to report that individual to the authorities for action.
In addition, there were numerous articles in virtually every New York newspaper reporting the actual use of isolation and quarantine in the city. 8 Dr. Royal S. Copeland, Health Commissioner of New York City, also issued recommendations to the general public, stating that “Persons who become infected with the disease should be placed in a room where no other person sleeps. No one should come into contact with anything the patient uses.” 9 The Department of Health went even further, however, and had officers actually check the death certificates when influenza and pneumonia was given as the cause of death to make sure that all cases were being reported as required by the newly amended Sanitary Code. 10
Furthermore, there is evidence that so many influenza cases were being isolated that superintendents of Department of Health hospitals became concerned with their ability to provide enough beds in their isolation wards, believing that the Sanitary Code required the specific use of isolation wards or rooms. 11 This does not even begin to account to the thousands of New Yorkers who were diagnosed with influenza and admitted to dozens of New York City hospital isolation wards during the period of time we studied.
On September 27, as civilian cases mounted, Copeland again stated that since the disease first appeared in the city, all reported cases had been isolated, and that health officials were making sure that quarantines were being maintained in private homes. 12 That same week, JAMA, in its “Medical News” section, reported that Copeland and the New York Department of Health had enacted a policy of isolation and quarantine. 13
Lastly, a number of New York City private physicians took the order to isolate and quarantine cases and suspected contacts so seriously that many placed quarantine placards of their own making on the doors of homes where there had been a case of influenza. 14
Consequently, we believe there is more than ample documentary evidence that the New York City Department of Health not only enacted but also acted upon a policy of isolation and quarantine of influenza cases and suspected contacts.
Health Commissioner Royal Copeland
There has been some speculation that Dr. Copeland 1) lied to the press about the use of NPI in New York; 2) was ineffective as Health Commissioner because of his political affiliations with the Tammany machine and his training as a homeopath; 3) and that he lied about mounting a quarantine effort in New York because he felt the need to save face in the wake of a quarantine policy implemented in Jersey City.
In our opinion, we believe that the first two points are not germane to this discussion, and we discuss why in greater detail in the endnote to this paragraph. Determining the honesty of a historical personage without direct evidence is impossible and judging the character of an early-20th century health official based on the type of medical school he attended or his political affiliation is a slippery slope of historical analysis. 15
As for the last assertion, it appears that this conclusion has been inappropriately derived from a New York Times article, which happened to report on the Jersey City quarantine in the very next line after reporting on New York’s. 16 When reading a newspaper one cannot assume that a causal relationship exists simply because one event in the text follows another.
There also have been assertions that Copeland lied to the press but told the “truth” to a gathering of privately practicing physicians in a speech that was subsequently reprinted in the New York Medical Journal. 17 Specifically, some have suggested that Copeland debunked the idea of quarantine and isolation in New York in this speech. We believe it is quite clear from reading the text of the speech that Copeland was discussing the futility of confining all New Yorkers to their homes rather than selectively requiring those who were ill to be placed in isolation and their contacts in household quarantine. If anything, Copeland’s comments on the communicability of influenza suggest his belief that it was necessary to isolate cases and quarantine family members. 18
These critics further argue that because the word quarantine does not appear in these speeches given by Copeland and Harris, or in the annual report of the New York City Department of Health, published nearly 9 months later, the absence of evidence equals evidence of absence. This applies a historical tautology to examining the evidence and is, in our opinion, an inadequate way to arrive at any substantive conclusions about the historical record.
Additional Observations on New York City
That said, it is critical to note, as we do in our JAMA paper, that an early PHRT [public health response time] as seen in New York’s quarantine and isolation protocol [-11 days] did not, in and of itself, guarantee success in terms of reducing excess death rates. New York City, it must be recalled, ranked only 15th among the 43 cities (the middle of the second quartile) in terms of favorable outcomes. Indeed, our JAMA paper clearly notes that New York City's experience was hardly exemplary when compared to the many cities in the study that mounted an early, sustained and layered response. Further, we hypothesize in our paper that while New York City acted early, it only employed one NPI (the quarantine and isolation order) and may have fared better if it implemented more layers of NPI for longer periods of time during the period studied.
Finally, some have asserted that New York City’s second and third wave mortality and morbidity rates were a direct result of a milder wave of influenza during the preceding spring. Yet there exists no peer-reviewed study demonstrating any scientific evidence supporting a hypothesis that the spring wave of 1918 conferred immunity to significant numbers of people for subsequent waves. Furthermore, our paper demonstrates no significant statistical association, positive or negative, between the excess mortality rates due to influenza in the 43 cities and the successive wave experiences (i.e., the Spring, 1918 wave, the Fall 1918 wave, the Winter, 1919 wave, and the Winter 1920 wave; See Figures 50-52, online supplement to JAMA paper, http://www.cdc.gov/ncidod/dq/pdf/flu_figures.pdf 
PDF 58 pages / 364 KB]
Chicago
Some have claimed that we did not cite a very important report entitled “Report of An Epidemic of Influenza in Chicago Occurring in the fall of 1918,” by Dr. John Dill Robertson, the Chicago Health Commissioner in our study. In fact, we do cite it, listing it under its correct title, Report and Handbook of the Department of Health of the City of Chicago for the Years 1911 to 1918 Inclusive, in the “City Annual Health Reports & Bulletins” section of our paper’s extensive, online, supplemental bibliography along with numerous other documents and newspaper articles pertaining to the Chicago experience. [http://www.cdc.gov/ncidod/dq/pdf/flu_bib.pdf PDF 76 pages / 341 KB] 19
To be sure, Chicago’s epidemic experience presents a complex social history of rolling public gathering bans that demands greater clarification rather than heated assertions. On September 26, 1918 the state ordered a ban on all public funerals (i.e., immediate family only) for those who died of influenza, an epidemiologically intriguing targeted public gathering ban. Chicago Health Commissioner Robertson followed up the funeral ban by ordering isolation for those diagnosed with influenza on October 1. Public dance halls were closed on the 12th and theaters on the 15th; finally, on October 17 there was a ban on all other "non-essential public gatherings" such as cabarets (wet and dry), banquets, dinners, club parties, athletic events, and stags. In accordance with the definitions of public gatherings we describe in our paper, we chose the September 26 date as the initiation of public gathering bans in Chicago. 20
But here is the key point: when re-running our data employing October 17 as the onset of public gathering bans, the public health response time changes minimally. The isolation order of October 1 would now become the first implementation of NPI, and the PHRT alters by +5 days (from -2 to +3 days). Even when applying this chronological interpretation, however, the correlation coefficients and statistical significance of the conclusions in our paper remain essentially unchanged. [See Tables 1 and 2]
Conclusion
The historical record is, by definition, incomplete and often fragmentary. Indeed, scholars frequently disagree about interpretations and meanings of the past and a healthy exchange of ideas makes for a better understanding of the human condition. While we make no claims to definitive conclusions about important questions raised by our paper, as scholars committed to scientific and historical inquiry, we insist on the rigor of peer-reviewed and evidence-based research to formally support or contradict any scientific study.
We hope that the additional historical insight and facts provided in this commentary clarify some of the misinformation that has recently been directed toward the study. We stand by the conclusions made in our JAMA paper and are confident that a careful, scholarly reading and review of our work demonstrates the rigor with which the research was performed, especially given the constraints and limitations of investigating a pandemic that occurred nearly a century ago.
End Notes
* Links to non-Federal organizations found at this site are provided solely as a service to our users. These links do not constitute an endorsement of these organizations or their programs by CDC or the Federal Government, and none should be inferred. CDC is not responsible for the content of the individual organization Web pages found at these links.
1 Howard Markel, Harvey B. Lipman, J. Alexander Navarro, Alexandra Sloan, Joseph Michalsen, Alexandra Minna Stern, and Martin S. Cetron, "Nonpharmaceutical Interventions Implemented by US Cities During the 1918-1919 Influenza Pandemic," JAMA 298 (August 8, 2007): 644-654.
2 US Centers for Disease Control and Prevention, Interim Pre-Pandemic Planning Guidance: Community Strategy for Pandemic Influenza Mitigation in the United States: Early, Targeted, Layered Use of Nonpharmaceutical Interventions. Atlanta, GA: Centers for Disease Control and Prevention; 2007. See, for example, Ferguson NM, Cummings DAT, Fraser C, Cajka JC, Cooley PC, Burke DS, "Strategies for Mitigating an Influenza Pandemic," Nature 2006;442(7101):448-452; Ferguson NM, Cummings DAT, Cauchemez S, et al, "Strategies for Containing an Emerging Influenza Pandemic in Southeast Asia," Nature 2005;437(7056):209-214; Longini IM Jr, Nizam A, Xu S, et al, "Containing Pandemic Influenza at the Source," Science 2005;309(5737):1083-1087; Germann TC, Kadau C, Longini IM Jr, Macken CA. "Mitigation Strategies for Pandemic Influenza in the United States," Proceedings of the National Academy of Sciences 2006;103(15):5935-5940; Glass RJ, Glass LM, Beyeler WE, Min HJ, "Targeted Social Distancing Design for Pandemic Influenza," Emerging Infectious Diseases 2006;12(11):1671-1681; Hatchett RJ, Mecher CE, Lipsitch M. "Public Health Interventions and Epidemic Intensity During the 1918 Influenza Pandemic," Proceedings of the National Academy of Sciences 2007;104(18):7582-7587; Bootsma MCJ, Ferguson NM, "The Effect of Public Health Measures on the 1918 Influenza Pandemic in US Cities," Proceedings of the National Academy of Science 2007;104(18):7588-7593. The last two papers, by Hatchett and Lipsitch and by Bootsma and Ferguson, in particular, arrive at similar conclusions to ours when analyzing the historical data on the American experience with influenza and NPI in 1918-19; Caley T, Philp D, McCrackin K. Quantifying Social Distancing Arising from Pandemic Influenza. Journal Royal Society Interface. 2007; doi10.1098/rsif.2007.1197 accessed on 12/26/07.
3 Howard Markel, Lawrence O. Gostin, and David Fidler, “Extensively Drug-Resistant Tuberculosis: An Isolation Order, Public Health Powers, and a Global Crisis,” JAMA 2007; 298(16):83-86; Martin S. Cetron and J. Landwith, “Public Health and Ethical Considerations in Planning for Quarantine,” Yale Journal of Biology and Medicine 2005;78(5):329-334; David P. Fidler, Lawrence O. Gostin, Howard Markel, “Through the Quarantine Looking Glass: Drug-Resistant Tuberculosis and Public Health Governance, Law and Ethics” The Journal of Law, Medicine and Ethics 2007; 35:616-628.
4 At this point in medical history, quarantines were not restricted solely to the cordoning off of entire communities, mandating individuals to lazarettos or quarantine islands, the complete closure of ports and city entrances, and other older, more traditional definitions of the term dating back to the Middle Ages. At many instances, including in 1918, there exist some anecdotal evidence that some people avoided the health department’s orders; at other times, there is documentary evidence that voluntary isolation and quarantine efforts were made by individuals and practicing physicians rather than the public health officials. See, for example, Howard Markel, Quarantine! East European Jewish Immigrants and the New York City Epidemics of 1892. (Baltimore: Johns Hopkins University Press, 1997); David Rosner, Hives of Sickness: Public Health and Epidemics in New York City (New Brunswick, NJ: Rutgers University Press, 1991); George Rosen, A History of Public Health (New York: MD Publications, 1955); Amy L. Fairchild, Ronald Bayer, and James Colgrove, Searching Eyes: Privacy, the State, and Disease Surveillance in America (Berkeley, CA: University of California Press/Milbank Books on Health and the Public, 2007).
5 Entry for Sept. 17, 1918. Minutes of the Board of Health of the City of New York, August 10, 1918 to December 31, 1918, Book 31, Municipal Archives of the City of New York, New York, New York. The gold standard of documentation for any municipal health department in the United States during the early 20th century would be the weekly minutes of the board of health and the sanitary code for that particular city.
6 Section 87 of the New York City Sanitary Code stated that “When no physician is in attendance, it shall be the duty of every person having knowledge of any person affected with any disease apparently or presumably infectious to at once report to the Department of Health all facts in relation to the illness and physical condition of any such person.” Section 89 of the Sanitary Code, as amended by the Board of Health on January 30, 1917, read, “It shall be the duty of every physician, immediately upon discovering a person affected with an infectious disease, to secure such isolation and quarantine of such person, or to take such other action as is or may be required by the Regulations of the Department of Health.” Section 90 required physicians to report to the Department of Health the death of every individual who died of an infectious reportable disease. New York Board of Health, Sanitary Code of the Board of Health of the Department of Health of the City of New York (New York: C.S. Nathan, 1920), 36-40. See also, Undated press statement ca. January 28, 1920, Speeches and Writings – New York Board of Health – Epidemics, Box 22, Royal S. Copeland Papers, Bentley Historical Library, University of Michigan, Ann Arbor, Michigan. This statement was made to the press on January 28, 1920 in the wake of a new spike in influenza cases. See, “5,589 New Cases in One Day Break Influenza Record,” New York Times, January 29, 1920, 1.
7 A portion of the letter was reprinted in “Seven New Cases of Influenza Here,” New York World, September 18, 1918.
8 See “Dr. Copeland Takes Steps to Combat Influenza Wave,” New York Herald, September 19, 1918, 5; “Health Commissioner Orders 5 Cases Here to Roosevelt Hospital,” New York Evening Journal, September 19, 1918; “Must Report All Spanish Influenza,” New York Times, September 18, 1918, 24; “Report 441 Cases of Influenza here,” New York World, September 21, 1918; “New York Prepared for Influenza Siege,” New York Times, September 19, 1918, 11; “Spread of Influenza Checked in the City,” New York Times, September 23, 1918, 9.
9 “Dr. Copeland Takes Steps to Combat Influenza Wave,” New York Herald, September 19, 1918, 5.
10 “City’s Influenza Cases Are Fewer,” New York World, September 22, 1918, 3.
11 Copeland addressed their concerns in a written statement. “’If the prevalence of influenza increases to any degree, it will be manifestly impossible to provide hospital care for any considerable proportion of the cases, and the general hospitals will have to be depended on to assist,’” he wrote. “’The restriction upon isolation of patients in hospitals should, therefore, not be severe. A modified quarantine will be accepted by the Department of Health institutions.’” Copeland then directed superintendents to allow influenza patients to be placed in the general wards of local hospitals so long as they were kept separated from pneumonia patients (to decrease the risk of those ill with influenza from developing pneumonia) and so long as ample space was allowed between beds. “Find 114 New Cases of Influenza Here,” New York Times, September 24, 1918, 9.
12 “New Influenza Cases in the City Doubled,” New York Times, September 28, 1918, 10. The first cases in the city came from ships entering the New York Harbor. In mid-November, after the second wave of the city’s epidemic had passed, Copeland gave an interview to the New York Times in which he explained the city’s response to this threat: “the only way to protect the citizens against possible contagion brought through the Port of New York was for the city to exercise its own powers of quarantine. So this is what we did.” “Epidemic Lessons Against Next Time,” New York Times, November 17, 1918, 42.
13 “Medical News: The Influenza Situation in New York,” JAMA 13 (September 28, 1918):1076-1077.
14 Copeland clarified the policy, stating that placarding by private physicians was not necessary, given that the Sanitary Code required that patients be isolated or quarantined. “New Cases Reach Higher Total Here,” New York Times, September 29, 1918, 15.
15 Royal Copeland was a member of the Tammany organization, a patronage-based Democratic political machine that exerted tremendous power over New York City (and state) politics throughout the 19th and well into the 20th centuries. But patronage does not necessarily equate with incompetence. To dismiss Copeland’s role in the influenza pandemic and the power of his position as Health Commissioner simply because he was appointed by Tammany mayor John F. Hylan, however, is to ignore the complex social and political history of Tammany Hall. For several excellent studies of Tammany, see Allan Franklin, The Trail of the Tiger, Being an Account of Tammany from 1789 (New York: Allan Franklin, 1928), David C. Hammack, Power and Society: Greater New York at the Turn of the Century (New York: Russell Sage Foundation, 1982), and Leo Hershkowitz, Tweed’s New York, Another Look (New York: Doubleday Anchor, 1978).
As for Copeland’s medical training, homeopathic practice was commonplace during the 19th century. Moreover, Copeland received his M.D. from the University of Michigan Homeopathic School, which required foundational training in all the dominant fields of the day, such as anatomy, microscopy, physiology, chemistry, and materia medica. Indeed, he completed these courses in the University of Michigan Medical School, one of the premier institutions of its kind in this era. As a result, Copeland had a deep appreciation for allopathic medicine, and he saw homeopathic medicine as an extension or alternative to allopathy, not as its polar opposite. Copeland wrote that homeopathy was “but one of many methods of treating illness,” noting that “it does not replace surgery, hygiene, biological medicine, chemical antidote, or physical therapeutics.” What is particularly striking about Copeland is that even as he treated his individual patients with homeopathic remedies during this period, he understood that public health required different methods, drawn squarely from bacteriology and epidemiology. For example, he stated, “a health commissioner who disregarded pest-infested and disease-breeding basements would not be worthy of the name.” See Natalie Robins, Copeland’s Cure: Homeopathy and the War Between Conventional and Alternative Medicine (New York: Alfred A. Knopf, 2005), 31,150. For a discussion of homeopathy and medical training, see also Kenneth M. Ludmerer, Learning to Heal: The Development of American Medical Education (New York: Basic Books, 1985).
16 “Must Report All Spanish Influenza,” New York Times, September 18, 1918, 24.
17 Royal S. Copeland, “General Survey of the Influenza Epidemic,” New York Medical Journal 17 (1918):715-718; see also, a companion speech delivered by Director of the Bureau of Preventable Diseases, Louis I. Harris, “Epidemiology and Administrative Control of Influenza,” New York Medical Journal 17 (1918):718-721. Both of these papers are cited in our paper’s extensive online bibliography, [http://www.cdc.gov/ncidod/dq/pdf/flu_bib.pdf]
18 This interpretation of Copeland’s speech was shared by others at the time. On November 9, 1918, the St. Louis Post-Dispatch reported on the printing of Copeland’s speech, noting that, “Dr. Copeland’s experience is that contact in the home has a far greater responsibility for the spread of the disease than any other agency or circumstance found to contribute to its prevalence.” This, the Post-Dispatch continued, was the reason why no general closure order or public gathering ban was implemented in New York City. “Science and Influenza,” St. Louis Post-Dispatch, November 9, 1918, 12.
It should also be noted that the New York Medical Journal was not a peer-reviewed journal. It was a weekly trade medical newspaper where most of the articles, including the articles by Copeland and Harris, were transcriptions of lectures to local medical societies. While we cannot claim to be able to divine when – or if – Copeland was “lying,” there are excellent reasons why he would not emphasize quarantine and isolation policy to a group of local practitioners at a medical society meeting. Since 1897, when then Health Commissioner Dr. Hermann Biggs made tuberculosis a mandatory reportable disease, New York City practitioners worried that such orders would cost them money in that they would lose their paying patients to public hospitals and doctors. This concern over the economic impact of public health doctors “poaching” paying patients appeared and re-appeared during every epidemic crisis in New York over the following two decades. The critical final paragraph of Copeland’s lecture, therefore, can easily be interpreted as an enjoinder to private physicians to aid in the Department of Health’s isolation and quarantine policy, and to adhere to the amended Sanitary Code with respect to influenza and pneumonia. See, for example, Daniel M. Fox, “Social Policy and City Politics: Tuberculosis Reporting in New York, 1889-1900,” Bulletin of the History of Medicine 49 (1975):169-195.
19 The correct citation, and the one listed in our bibliography, is John Dill Robertson, Report and Handbook of the Department of Health of the City of Chicago for the Years 1911 to 1918 Inclusive (Chicago, 1919).
20 “State Demands Report of All New ‘Flu’ Cases,” Chicago Tribune, September 26, 1918, 5.
Tables
Table 1. Published and alternate values for the study variables for Chicago using October 17, 1918 as an alternate date that public gatherings were banned.
| Published | Alternate | |
|---|---|---|
First Case Date |
9/17 |
9/17 |
Mortality Acceleration date |
9/28 |
9/28 |
Date of First Nonpharmaceutical Intervention |
9/26 |
10/1 * |
Public Health Response Time, d |
-2 |
3 |
Total No. of Days of Nonpharmaceutical Interventions |
68 |
47 |
Date of Peak Excess Death Rate |
10/21 |
10/21 |
Time to Peak, d |
25 |
20 |
Magnitude of First Peak, Excess Deaths/100,000 Population |
84.8 |
84.8 |
Excess Pneumonia and Influenza Mortality, Deaths/100,000 Population |
373.2 |
373.2 |
* Date that Health Commissioner Robertson orders isolation of all influenza cases.
Table 2. Published and alternate Spearman's rank correlation coefficients and p-values for the associations between public health response time (PHRT) and time to peak, magnitude of first peak excess death rate (peak EDR) and total EDR; and between the number of days of nonpharmaceutical interventions (total NPI-days) and total EDR for Chicago using October 17, 1918 as an alternate date that public gatherings were banned
| Association (corresponding Figure in manuscript) | Published | Alternate |
|---|---|---|
PHRT X Time to peak (Figure 1A) |
r = -0.74, P < .001 |
r = -0.73, P < .001 |
PHRT X Peak EDR (Figure 1B) |
r = 0.31, P = .02 |
r = 0.31, P = .02 |
PHRT X Total EDR (Figure 1C) |
r = 0.37, P = .008 |
r = 0.35, P = .01 |
Total NPI-days X Total EDR (Figure 1D) |
r = -0.39, P = .005 |
r = -0.35, P = .01 |
* Links to non-Federal organizations found at this site are provided solely as a service to our users. These links do not constitute an endorsement of these organizations or their programs by CDC or the Federal Government, and none should be inferred. CDC is not responsible for the content of the individual organization Web pages found at these links.