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July 1, 2020

Mortality and Morbidity: The Measure of a Pandemic

Author Affiliations
  • 1Deputy Editor, JAMA
  • 2Editor in Chief, JAMA
JAMA. 2020;324(5):458-459. doi:10.1001/jama.2020.11761

By late May 2020, more than 100 000 individuals in the US died of coronavirus disease 2019 (COVID-19).1 News reports lamented the number, comparing it to the capacity of a large football stadium or a small town and noting its similarity to the number of US soldiers killed in World War I or in the Korean and Vietnam wars combined.2

Death seems like it should be an accurate measure of the pandemic’s evolution and effects—the worst outcome, an unequivocal outcome. However, the number of deaths attributed to COVID-19 in official reports is likely an underestimate of deaths caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). In addition, the statistic does not incorporate deaths indirectly attributable to the virus and the measures used to contain it.

Early in the pandemic, people who died of COVID-19 may not have been recognized due to inadequate knowledge of the infection or lack of testing availability, and their deaths may have been attributed to another respiratory disease, such as influenza.3 Individuals who died at home or in nursing homes may not have been tested for or diagnosed with COVID-19, and those deaths would not be counted in mortality related to the pandemic.

In addition, other deaths not from COVID-19 may have resulted from the pandemic, particularly related to concerns about exposure to SARS-CoV-2 and social distancing measures. One study showed that hospitalizations at Veterans Affairs facilities for 6 emergency and potentially life-threatening conditions, such as myocardial infarction and stroke, declined by 41.9% during the first weeks of the pandemic (from 77 624 admissions in weeks 5-10 of 2020 to 45 155 admissions in weeks 11-16).4 People may have ignored symptoms as they obeyed stay-at-home orders or were concerned about going to a hospital where they might contract the virus. Data on whether avoidance of care has translated into additional deaths are not yet available.

In contrast, quarantine measures also may have led to a decline in deaths from other causes, such as vehicular crashes because fewer people were driving on the roads. A study from California found that traffic crashes, injuries, and fatalities decreased by half in the month after the state’s stay-at-home mandate.5 In addition, social distancing measures have been shown to decrease the incidence of influenza6 and other respiratory viruses, presumably decreasing deaths from these causes.

How then is it possible to estimate the true effect of this pandemic, accounting for these different factors? One way is to estimate excess deaths (ie, deaths beyond what would be expected). In this issue of JAMA, Woolf and colleagues7 compared the number of excess deaths in the US between March 1, 2020, and April 25, 2020, with the preceding 6 years. Based on data from 2014 to 2019, the authors expected 419 058 deaths but observed 505 059, an excess of 87 001 deaths. They estimated that 65% were attributable to COVID-19, leaving 35% of the excess deaths unexplained. Some of these deaths may be due to inaccuracies in the data (eg, misclassified deaths, incomplete reports) or to avoidance of care. If the same pattern continued through the end of May, there would be, as reported, 100 000 deaths attributable to COVID-19, but an estimated 135 000 total deaths attributable to the pandemic. Woolf et al7 also provide state-by-state estimates of excess deaths and a more detailed account of the 5 states most affected by COVID-19.

Estimating excess deaths is not a new approach. Similar calculations have been done to assess the effect of common and uncommon causes of mortality. For example, a study used this calculation to analyze the obesity epidemic and found excess deaths attributable to obesity vs normal weight.8 After Hurricane Maria in Puerto Rico, estimated counts of excess deaths ranged from 1139 to 4645, compared with an official death toll of 64.9

However, focusing only on death as a measure of the effect of the pandemic overlooks morbidity. Just as with mortality, there are direct and indirect effects, many of which cannot yet be fully appreciated. Hospitalizations from COVID-19 may be a valuable direct measure to help assess morbidity. Some morbidities are still being evaluated. For example, reports of children developing a multisystem inflammatory syndrome after COVID-19, with potential cardiac damage, have emerged.10 It is too soon to know whether the severe pulmonary damage observed in some adults who recovered from severe COVID-19 will have long-term respiratory implications.

In addition, although the mitigation efforts (eg, stay-at-home orders, school closures) have been successful in decreasing the rate of spread of the virus, they have had indirect effects. For example, reports of domestic violence have increased.11 Social isolation has been associated with psychological distress. In a national survey from April 2020 that involved 1468 respondents, 13.6% of adults reported serious psychological distress, compared with 3.9% in 2018, at levels that predict serious mental illness.12 School closures, especially if they continue in the fall, may harm children, especially those at social risk. Not only could educational progress be affected, but children who rely on school breakfast and lunch may be going hungry. Children who rely on school-based health centers might not receive some health services.13 Closures of businesses, whether temporary or permanent, may have health effects. With the unemployment rate reaching 13.3% in May 2020,14 many individuals may have to choose between paying the rent and seeing a physician or refilling a prescription.

The COVID-19 pandemic and the social distancing measures used to contain the spread of the virus have altered everyday life in the US and produced excess mortality and morbidity. It is important to have an accurate count of the number of deaths that have resulted from this pandemic either directly or indirectly. Woolf et al7 have provided an early count of these numbers by estimating excess deaths from COVID-19 and other causes. The goal is to update these counts in the fall of 2020 so that an accurate measure of the status of the pandemic and of efforts to mitigate the related morbidity and mortality are available to be debated prior to the presidential election.

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Article Information

Corresponding Author: Jody W. Zylke, MD, Deputy Editor, JAMA, 330 N Wabash Ave, Ste 39300, Chicago, IL 60611 (jody.zylke@jamanetwork.org).

Published Online: July 1, 2020. doi:10.1001/jama.2020.11761

Conflict of Interest Disclosures: None reported.

Coronavirus Disease 2019 (COVID-19): cases in the US. Centers for Disease Control and Prevention website. Updated June 21, 2020. Accessed June 22, 2020. https://www.cdc.gov/coronavirus/2019-ncov/cases-updates/cases-in-us.html
Anthony  T. American virus deaths at 100,000: what does a number mean? AP News. May 27, 2020. Accessed June 6, 2020. https://apnews.com/f768f47203908b834e245fbf7f0b3ccc
Gill  JR, DeJoseph  ME.  The importance of proper death certification during the COVID-19 pandemic.   JAMA. Published online June 10, 2020. doi:10.1001/jama.2020.9536PubMedGoogle Scholar
Baum  A, Schwartz  MD.  Admissions to veterans affairs hospitals for emergency conditions during the COVID-19 pandemic.   JAMA. Published online June 5, 2020. doi:10.1001/jama.2020.9972PubMedGoogle Scholar
California crashed during “shelter-in-place” orders, March-April 2020. Road Ecology Center website. Accessed June 6, 2020. https://roadecology.ucdavis.edu/resources/stayathome-crashes
Sakamoto  H, Ishikane  M, Ueda  P.  Seasonal influenza activity during the SARS-CoV-2 outbreak in Japan.   JAMA. 2020;323(19):1969-1971. doi:10.1001/jama.2020.6173PubMedGoogle ScholarCrossref
Woolf  SH, Chapman  DA, Sabo  RT, Weinberger  DM, Hill  L.  Excess deaths from COVID-19 and other causes, March-April 2020.   JAMA. Published online July 1, 2020. doi:10.1001/jama.2020.11787Google Scholar
Flegal  KM, Graubard  BI, Williamson  DF, Gail  MH.  Excess deaths associated with underweight, overweight, and obesity.   JAMA. 2005;293(15):1861-1867. doi:10.1001/jama.293.15.1861PubMedGoogle ScholarCrossref
Santos-Lozada  AR, Howard  JT.  Use of death counts from vital statistics to calculate excess deaths in Puerto Rico following Hurricane Maria.   JAMA. 2018;320(14):1491-1493. doi:10.1001/jama.2018.10929PubMedGoogle ScholarCrossref
Whittaker  E, Bamford  A, Kenny  J,  et al.  Clinical and laboratory characteristics of 58 children with a pediatric inflammatory multisystem syndrome temporally associated with SARS-CoV-2.   JAMA. Published online June 8, 2020. doi:10.1001/jama.2020.10369PubMedGoogle Scholar
Boserup  B, McKenney  M, Elkbuli  A.  Alarming trends in US domestic violence during the COVID-19 pandemic.   Am J Emerg Med. Published online April 28, 2020. doi:10.1016/j.ajem.2020.04.077PubMedGoogle Scholar
McGinty  EE, Presskreischer  R, Han  H, Barry  CL.  Psychological distress and loneliness reported by US adults in 2018 and April 2020.   JAMA. Published online June 3, 2020. doi:10.1001/jama.2020.9740PubMedGoogle Scholar
Sharfstein  JM, Morphew  CC.  The urgency and challenge of opening K-12 schools in the fall of 2020.   JAMA. Published online June 1, 2020. doi:10.1001/jama.2020.10175PubMedGoogle Scholar
The employment situation—May 2020. Bureau of Labor Statistics. June 5, 2020. Accessed June 6, 2020. https://www.bls.gov/news.release/pdf/empsit.pdf
3 Comments for this article
Missing Scenarios
Carey Page, MD | UTHSCSA
Considerations missing from the discussion are the numbers of patients dying from other causes that were also infected by SARS-CoV-2. Myocardial infarction, gun-shot wounds, auto accidents as the proximate cause of death were often (by rule) attributed to COVID-19 if the person tested positive at the time of death. There were also economic incentives to attributing the "cause of death" to COVID-19. This misappropriation may or may have not been corrected as time passed.

Similarly absent from the analysis is the consideration of economic and social conditions that required people to venture into the "economy" in spite of
the "shelter in place" rules. Economic distress from the shutdown and loss of income caused many to "go to the store" rather than opting for delivery. In fact, the most frequent source of person-to-person transmission is "in the home." In NYC, the most frequent source of community acquired infection was the home (≈66%).

So; this paper does a good job as far as it goes but leaves out some really significant scenarios: some political and economic, and some real-life.
Accurate Measurement of Mortality and Morbidity for COVID-19
Michael McAleer, PhD (Econometrics), Queen's | Asia University, Taiwan
The clear and concise editorial by the Editor-in-Chief and Deputy Editor of JAMA is concerned with the important issue of the accurate measurement of mortality and morbidity for COVID-19.

Such accurate measurement of mortality and morbidity is essential for optimal public health policy considerations, which are affected by political considerations, especially in a Presidential election year.  

As of 3 July 2020, almost 3 million individuals have been diagnosed as COVID-19 positive, with over 1340,000 deaths, in the USA (https://www.worldometers.info/coronavirus/).

The estimated number of deaths that are directly attributable to COVID-19 is undeniably an underestimate as the numbers do not seem to
include cases where individuals were not tested for the disease before or after death, as well as misdiagnosis due to overlapping and disguised factors.

Deaths that could be indirectly attributed to COVID-19 include avoidance of care, and lack of access to medical and health care due to other socio-environmental factors such as poverty, hunger and racism, which are often found to be overlapping.

Estimates based on "unexplained excess deaths" are aggregate measures that do not take account of mitigating factors, such as the effects of self isolation, social distancing, quarantining, lockdowns, reduced traffic accidents, domestic violence, and deaths arising from COVID-19-induced psychological stress and mental illness.

Clear and consistent definitions across all measuring facilities, including all States, are essential to obtain accurate measures of mortality and morbidity to enable meaningful public health policy deliberations.
Brian Reddy |
From the excess deaths study:

"87 001 were excess deaths, of which 56 246 (65%) were attributed to COVID-19"

i.e. 56,246 / 87,001 = ~65%


87,000 * 0.65 = 56,246

Important to note, in order for COVID deaths to make up 65% of excess deaths then,

56,246 * 1.55 = 87,001

Excess deaths must be ~50% greater than COVID deaths. Not 35%.

From your editorial,

"If the same pattern continued through the end of May, there would be, as reported, 100 000 deaths attributable to COVID-19, but an estimated 135 000 total
deaths attributable to the pandemic."

100,000 / 135,000 = 74%

Since 1-0.65 = 35%, I believe you thought to do 100,000 * 1.35 = 135,000

But 100,000 * 1.5 = 150,000.

That way,

100,000 COVID deaths / 150,000 excess = 65% of excess deaths (for lack of a better term) directly attributable to COVID.

So, COVID reported deaths * ~1.5 = excess deaths, that way COVID deaths make up 65% of excess deaths.