Health Information on the 2019 Coronavirus

A Policy Brief of the Howard H. Baker Jr. Center for Public Policy

March 13, 2020

Using publicly available data on influenza and emerging research on COVID-19, this brief provides details on COVID-19 transmission, contagiousness, disease burden, and suggested guidelines on limiting the spread of the infection. This brief is part of a series that will be produced over the next few weeks forecasting the health and economic impact of the virus. The Department of Health for the State of Tennessee is also providing ongoing updates. As this is an emerging issue dealing with a novel virus, information included here is potentially subject to revision as new research and data emerge.

Overview

On December 31, 2019, the World Health Organization’s (WHO) China Country office was informed about cases of pneumonia with an unknown cause that had been detected in Wuhan City, located in the Hubei Province. Over the next three days, from the 31st to the 3rd of January, 2020, a total of 44 cases were reported to WHO by the national authorities in China. On February 11, 2020, the WHO announced that the disease caused by the new coronavirus would be known by the official name of COVID-19.

In response to the global spread of COVID-19, on March 11, 2020, the WHO declared a pandemic due to the worldwide spread of the disease in a short amount of time. President Donald J. Trump also addressed the nation from the Oval Office about the administration’s plan to mitigate exponential spread in the United States and on March 13, 2020 he declared a national emergency.

The 2019 Coronavirus (COVID-19) is part of a family of viruses that includes the common cold, but the 2019 strain of coronavirus has not been previously identified in humans. There is currently no vaccine, nor a cure for COVID-19. An antiviral drug, Remdesivir, which is made by Gilead Sciences, is currently being used for patients with severe symptoms.

COVID-19 causes respiratory symptoms, including fever, cough, shortness of breath, and other breathing difficulties. In severe cases, the infection can cause pneumonia, severe acute respiratory syndrome, kidney failure, and death.

As of noon, on Friday, March 13, 2020, according to tracking of COVID-19 by Johns Hopkins University, the virus has spread to:

Global: over 137,385 cases in more than 114 countries, with 5,088 deaths and 69,779 people recovered

United States: 1,268 cases, 33 deaths, 6 recoveries

Tennessee: 18 cases, 0 deaths, 0 recoveries

Davidson: 6
Knox: 1
Shelby: 2
Sullivan: 1
Williamson: 8

The State of Tennessee is providing regular updates. S&P Global is currently predicting a peak in cases in June 2020.

Key Facts

Based on current global figures, COVID-19 is 34 times more deadly than seasonal influenza (flu) in the US. The crude case fatality rate for seasonal influenza in the US is approximately 1 in 1,000 infected (or 0.1%), while the global rate for COVID-19 is currently at 34 in 1,000 (or 3.4%). The US numbers for COVID-19 are still in line with this crude case fatality rate, although increased detection through testing and awareness may bring this number down. Some estimates from data on China put the case fatality rate for COVID-19 at 14 in 1,000 (or 1.4%), which is still 14 times more than US seasonal influenza rates.

The incubation period for COVID-19 is estimated to be 2 to 14 days, with an average of 5 days before symptoms emerge. Individuals are thought to be most infectious when they are most symptomatic, but there is a possibility that individuals may be contagious before the onset of symptoms (around 24-48 hours prior to symptoms). The serial interval, or time between successive cases, is 5 to 6 days for COVID-19, while for influenza it is 3 days.

In these ways COVID-19 is unlike influenza. Influenza is more likely to be transmitted before the onset of symptoms, has a shorter median incubation time, the time from infection to appearance of symptoms, and a shorter amount of time between successive cases (3 days). This means that influenza can spread more quickly than COVID-19, but is less contagious.

Similar to influenza, however, COVID-19 is primarily transmitted through droplet spread when infected individuals sneeze or cough, and may also be transmitted by contact with an infected individual, or by surfaces or other objects that have come in contact with droplets from someone who is infected. Research on other coronaviruses suggest that the virus can survive on surfaces for up to 9 days at room temperature.

COVID-19 disproportionately affects those with underlying health conditions, including those with heart disease, diabetes, lung disease, and older individuals. According to the WHO, for those not at high risk, the illness is generally mild, particularly for children and young adults, and for most people in most locations the risk of catching the virus is still low.

This is different than influenza, where children are the important drivers of transmission and are at higher risk of severe cases.

However, members of the public should consider that even if they are not at high risk they may still infect those who are. The WHO estimates that without preventative measures and in an entirely susceptible population, each individual with COVID-19 will infect between 1.5 to 2.5 others, though some research puts the average at 3.28, with a median of 2.79. This is a higher than the estimated contagious rate than influenza.

For COVID-19 the recovery time for those with a mild case is about two weeks, while people with a severe or critical case recover within three to six weeks. COVID-19 also produces a higher fraction of severe cases than influenza, with 15% requiring oxygen and 5% requiring ventilation.

Quick Summary

COVID-19 has similar symptoms and transmission modes to influenza, spreads more slowly, and is less likely to affect children, but cases of it are more contagious, are more likely to be severe, and more likely to be deadly. There is no cure and no vaccine.

Individual Prevention

According to guidance from the Center for Disease Control (CDC), to avoid spreading the illness:

Individuals who are not at high-risk:

avoid close contact with those who are sick (a minimum of 3 feet), avoid touching your eyes, nose, and mouth, stay home if you are feeling sick or if you have been traveling internationally, cover your cough or sneeze with a tissue and throw the tissue in the trash, clean and disinfect frequently touched objects and surfaces using bleach or ethyl alcohol dilutions (60-70%), wash your hands often with soap and water for 20 seconds, avoid public transit and closed-in spaces where air is recirculated.

High-Risk individuals:

stock up on necessary supplies to limit the need to leave your home, take precautions to keep space between yourself and others (a minimum of 6 feet), when in public keep away from others who are sick, limit close contact, and wash your hands frequently with soap and water for 20 seconds, avoid crowds as much as possible, avoid cruises and other non-essential travel, and during the event of a COVID-19 outbreak in your community, stay home as much as possible to reduce the risk of exposure.

Everyone should follow other public health guidance.

COVID-19 Transmission

With any disease there are two main modes of transmission: direct and indirect. In direct transmission, the pathogen is transmitted by direct contact between a diseased subject and a non-diseased subject. Direct transmission can occur when an infected person touches or exchanges body fluids with someone else, including in the form of droplet spread—that is relatively large, short-range aerosols produced by sneezing, coughing, or speaking.

In indirect transmission, the pathogen is transmitted between a diseased subject and a non-diseased subject by an intermediary, such as air particles, inanimate objects (vehicles), or animate intermediaries (vectors) that can carry infection. Airborne transmission occurs when an infectious agent is carried by dust or droplet nuclei (<5 microns in size) suspended in the air, potentially traveling over expansive areas. Vehicle transmission occurs when an infectious agent is passively transmitted by inanimate objects, such as food, water, and fomites— objects or materials that can carry infection, such as hard surfaces and materials. Vector transmission occurs when an infectious agent is transmitted by an intermediate organism, including animals and insects.

According to the CDC, and based on existing evidence:

COVID-19 appears to be transmitted directly, person-to-person in close contact (within 6 feet), through droplet spread produced when an infected person coughs or sneezes.

Other diseases transmitted via airborne droplets include other coronaviruses, such as severe acute respiratory syndrome (SARS-CoV) and Middle East respiratory syndrome (MERS-CoV), as well as other illnesses like Influenza (Flu) and Pertussis (Whooping Cough).

While the CDC acknowledges it is possible that transmission of COVID-19 can occur indirectly by touching a surface or object that has the virus on it and then touching the mouth, nose, or eyes (e.g., self-inoculation), which is a mode of transmission discussed in guidance on the virus by the WHO, at this time the CDC states that it is not thought to be the primary way that disease spreads.

Given the possibility that transmission may occur indirectly due to contact with contaminated surfaces, it is important to note that based on a recent 2020 study published in the Journal of Hospital Infection on human coronaviruses (not specifically COVID-19) human coronaviruses:

can remain infectious on inanimate surfaces at room temperature for up to 9 days, and a concentration of 70% ethyl alcohol is recommended by the WHO for disinfecting small surfaces, and surface disinfection with 0.1% sodium hypochlorite (bleach) concentration significantly reduces coronavirus infectivity on surfaces within 1 minute.

Notably, many antibacterial products currently for sale, including wipes and sanitizers, are alcohol-free, or do not reach the ethyl alcohol concentration level recommended by the WHO (70%) or the CDC (60%). As a result, these products may not be as effective as needed in decontaminating surfaces for COVID-19. There may need to be more public communication on this topic as the demand for hand sanitizer and other disinfecting products increases dramatically.

COVID-19 Contagiousness

Another consideration for disease transmission is its basic reproduction number, sometimes denoted as R0 (pronounced R nought), which is the number of cases that can be expected to be generated by one infected case in a population where all individuals are susceptible to the virus. Notably, this figure also includes an assumption that no attempts are made to curb the transmission of the disease. The R0 figure can be thought of as an indication of the contagiousness of a disease.

In a 2020 article published in the Journal of Travel Medicine researchers examined 12 studies published from January 1, 2020 and February 7, 2020 that had estimated the R0 of COVID-19. The review found an average R0 of 3.28 across the studies, meaning in a susceptible population and without intervention, each infected individual would likely infect three or more others on average. This research also found that the median R0 of the studies examined was 2.79, which the authors noted exceeded the WHO estimates of a range between 1.4 and 2.5. This is a higher than the estimated contagious rate than influenza.

Projections purely based on R0 are apocalyptic, however, it is highly unlikely that every population will be susceptible to COVID-19 and that containment or mitigation efforts to limit the spread of the virus will not be made.

The flattening of the R0 curve, and to avoid such outcomes, the infection rate can be slowed through the public health interventions, including non-pharmaceutical interventions (NPIs), like social distancing— which includes everything from self-isolation and school closures, to limiting handshakes and other forms of interpersonal contact—strategies that are discussed more in-depth below.

COVID-19 Susceptibility

While COVID-19 can infect people of all ages, some population groups are at a considerably higher risk of contracting COVID-19 and encountering severe complications that require intensive medical care. Risk of complications also increases with age starting around 40 years old. However, those most vulnerable to the virus are individuals over the age of 60 or those with underlying health conditions, such as cardiovascular disease, diabetes, chronic respiratory disease, and cancer.

The CDC has provided the following further guidance on underlying conditions that may increase the risk of serious COVID-19 for individuals at any age:

Blood disorders (e.g., sickle cell disease or on blood thinners)
Chronic kidney disease as defined by your doctor. Patient has been told to avoid or reduce the dose of medications because kidney disease, or is under treatment for kidney disease, including receiving dialysis
Chronic liver disease as defined by your doctor (e.g., cirrhosis, chronic hepatitis). Patient has been told to avoid or reduce the dose of medications because liver disease or is under treatment for liver disease.
Compromised immune system (immunosuppression) (e.g., seeing a doctor for cancer and treatment such as chemotherapy or radiation, received an organ or bone marrow transplant, taking high doses of corticosteroids or other immunosuppressant medications, HIV or AIDS)
Current or recent pregnancy in the last two weeks
Endocrine disorders (e.g., diabetes mellitus)
Metabolic disorders (such as inherited metabolic disorders and mitochondrial disorders)
Heart disease (such as congenital heart disease, congestive heart failure and coronary artery disease)
Lung disease including asthma or chronic obstructive pulmonary disease (chronic bronchitis or emphysema) or other chronic conditions associated with impaired lung function or that require home oxygen
Neurological and neurologic and neurodevelopment conditions [including disorders of the brain, spinal cord, peripheral nerve, and muscle such as cerebral palsy, epilepsy (seizure disorders), stroke, intellectual disability, moderate to severe developmental delay, muscular dystrophy, or spinal cord injury]

There is currently very little known about the susceptibility of pregnant women to COVID-19, but early indicators suggest the virus may make them more susceptible to respiratory illness in general. Based on a recent 2020 article published in the academic journal Viruses on maternal and infant outcomes for other observed cases in human coronavirus outbreaks, such as SARS-CoV and MERS-CoV, pregnant women may be at risk of more severe cases of the illness, but it is unlikely that there is intrauterine maternal-fetal transmission.

Currently, there is no information about whether pregnant women can transmit COVID-19 through breast milk. According to the CDC, in limited studies from SARS cases, another coronavirus, the virus was not detected in breast milk. However, interim guidance from the CDC is that mothers with infants take precautions to avoid spreading the illness to their child.

Most confirmed cases of COVID-19 have occurred in adults thus far, though infections in children and infants have been reported. Current information, although limited, suggests that children are not any more susceptible to COVID-19 than adults. Symptoms appear to be similar in children and adults; however, symptoms are generally more mild in children.

This is different than influenza, where children are the important drivers of transmission and are at higher risk of severe cases.

Based on a recent 2020 article published in the Journal of the American Medical Association on the characteristics of the COVID-19 outbreak in China, and using data from 44, 672 cases, the age-distribution of the illness is:

less than or equal to 80 years old: 3% (1,408 cases)
30-79 years: 87% (38,680 cases)
20-29 years: 8% (3,619 cases)
10-19 years: 1% (549 cases)
less than 10 years old : 1% (416 cases)

This is also displayed in the figure below.

Using data from Johns Hopkins University, this graph shows the US new confirmed cases of COVID-19 as a daily change:

COVID-19 Disease Burden

According to the WHO, for those not at high risk, the illness is generally mild, particularly for children and young adults, and for most people in most locations the risk of catching the virus is still low.

However, the WHO also notes that about 1 in 5 people with the illness will require hospital care, which mathematically translates into 20,000 cases of COVID-19 will require hospitalization for every 100,000 cases.

In comparison, for the 2019-2020 US influenza season, 57.9 cases in 100,000 required hospitalization. Even for the most susceptible population to influenza, which is those over the age of 65, for the 2019-2020 influenza season, there were 147.5 cases of hospitalizations in 100,000. The hospitalization rate projected for COVID-19 is exponentially higher than the rate for influenza, even when considering the highest risk populations.

Based on a recent 2020 article published in the Journal of the American Medical Association on the characteristics of the COVID-19 outbreak in China, and using data from 44, 415 cases, the spectrum of disease severity for COVID-19 was:

Mild: 81% (36 ,160 cases)
Severe: 14% (6,168 cases)
Critical: 5% (2,087 cases)

This is displayed in the figure below.

This indicates that an estimated:

3,000 cases will require oxygen per 100,000 cases of COVID-19
1,000 cases will require ventilation per 100,000 cases of COVID-19

Notably the CDC estimates that the burden of illness during the 2018–2019 influenza season in the US included an estimated:

35.5 million cases of influenza
16.5 million saw a health care provider for their illness
490,600 required hospitalization
34,200 died from influenza

According to the CDC, the number of influenza-associated illnesses that occurred last season was similar to the estimated number of influenza-associated illnesses during the 2012–2013 influenza season when an estimated 34 million people had symptomatic influenza illness.

COVID-19 Case Fatality Rate

The crude case fatality rate (CFR) is how epidemiologists calculate the killing power of a disease. The CFR for any illness can be calculated by the following formula (here presented by 1,000, though by 100 cases is most common):

Based on current global figures, and using this formula, COVID-19 is 34 times more deadly than the flu. The crude case fatality rate for the flu is 1 in 1,000 infected, the global rate for COVID-19 is 34 in 1,000. It is important to note that for the immediate future this number will likely fluctuate as researchers attempt to more fully understand the severity of the disease.

Some have noted that the global crude case fatality rate may be inflated due to the lack of widespread testing, or because those with mild symptoms have not been tested. This is a legitimate critique and is also known as ascertainment bias.

For the crude case fatality rate in the US to be the same as the influenza, as some hopefully suggest, then there would have to be more than 33,000 cases of COVID-19 in the US that have yet to be detected. This is the reason that widespread testing is critical. Tennessee has only conducted 97 tests to date, which appears to be far behind most of the world according to recent reporting.

In comparison to the most recent influenza season in the US, which had a CFR of 1 in 1,000 (0.1%) and using figures for countries with more current cases than the US as reported by Johns Hopkins University as of Friday, March 13, 2020, COVID-19 is:

45 times (4.5%) more deadly than influenza based on Hubei Province, China, which includes the city of Wuhan
45 times (4.5) more deadly than influenza based on Iran
67 times (6.7%) more deadly than influenza based on Italy
8 times (0.83%) more deadly than influenza based on South Korea
28 times (2.8%) more deadly than influenza based on Spain
2 times (0.22%) more deadly than influenza based on Germany
21 times (2.1%) more deadly than influenza based on France

Based on the same 2020 article published in the Journal of the American Medical Association that is cited above on the characteristics of the COVID-19 outbreak in China, researchers calculated the following case fatality rates:

2.3% of all confirmed cases (1,023 of 44 ,672 confirmed cases)
8.0% in patients 70-79 years or older (312 of 3,918)
14.8% in patients who are 80 years or older (208 of 1,408)
49.0% in cases that become critical (1,023 of 2,087)

Some experts are expecting the case fatality rate could be as low as 1% (e.g, 10 in 1,000). This figure is still 10 times more deadly than influenza.

Using data from Johns Hopkins University, this graph shows the US deaths from COVID-19 as a daily change:

Best Practices and Prevention for Tennessee

Case projections purely based on mathematical models of the disease are apocalyptic, however, it is highly unlikely that every population will be susceptible to COVID-19 and that containment or mitigation efforts to limit the spread of the virus will not be made.

As detailed in an article on COVID-19 from The Economist in February 2020, “the aim of public-health policy, whether at the city, national or global scale, is to flatten the [R0] curve, spreading the infections out over time.” This is in order to avoid overwhelming the healthcare system, which is the situation now occurring in Italy.

The image below, which was adapted from a 2007 CDC guidebook on pre-pandemic planning, illustrates this dynamic:

When confronting pandemic illnesses, mitigating the social and economic consequences through early and targeted non-pharmaceutical interventions (NPIs), also known as community mitigation strategies, is critical. These are strategies that local governments, social organizations, and businesses can implement apart from those taken within a clinical setting. According to the CDC, the rationale of community mitigation is threefold:

Delay the exponential growth in infection rates, which spreads the distribution of cases thereby affording time for healthcare entities to prepare for a surge in demand.
Reduce the peak number of active cases.
Reduce the overall quantity of cumulative cases, thereby reducing morbidity and mortality.

The most commonly used NPIs are social distancing and closures. Indeed, communities, states, and business throughout the US have already announced multiple measures to contain the spread of the disease. For example, the University of Tennessee system recently announced that classes would be held online and large events on campus cancelled among other measures. Social distancing, or preventing close contact between others in social settings, and closures can help prevent person-to-person transmission of viral diseases like COVID-19, especially in socially dense environments such as schools.

Pandemic outbreaks can overwhelm healthcare systems and critical infrastructure at both the local and national level, which may compromise the quality and availability of medical care. Research shows social distancing and closures can help mitigate the impact by limiting disease transmission, reducing morbidity, and lowering mortality.

Of these strategies, research shows that school closures, limiting large public gatherings, and telecommuting can be highly effective during pandemics, allowing governments to avoid larger scale interventions. However, in order to maximize effectiveness, research shows that school closures need to be proactive, sometimes even in advance of an outbreak, and significant in duration.

To be clear, by slowing the rate of COVID-19 and therefore lowering the number of active cases at any given time, the burden placed on healthcare infrastructure can be more evenly distributed, reducing the strain on medical professionals and facilities in addressing individual cases. Ultimately, community mitigation strategies are aimed at protecting vulnerable populations most at risk of severe illness and groups that many be more socially or economically impacted by a pandemic.

Disclaimer: the information in this policy brief was produced by researchers, not medical or public health professionals, and is based on their best assessment of the existing knowledge and data available on the topic. It does not constitute medical advice and is subject to change as additional information becomes available.

Policy Brief Authors

Dr. Katie A. Cahill

Cahill is the Associate Director of the Howard H. Baker Jr. Center for Public Policy. She also is the Director of the Center's Leadership & Governance program and holds a courtesy faculty position in the Department of Political Science. Her area of expertise is public health policy. She leads the Healthy Appalachia project.

Hancen Sale

Sale is an undergraduate student researcher with the Center. He is a senior majoring in economics with a minor from the Center's public policy analytics program. He has worked on an NSF-funded project regarding rebel group grievances, as well as in supporting The White House's American Workforce Policy Advisory Board.

Policy Brief Reviewers

Dr. Kathleen C. Brown, MPH

Brown spent eight years working for the Knox County Health Department, initially as the regional epidemiologist, and then as the Director of Community Assessment and Health Promotion. She is an Associate Professor of Practice (non-tenure) in the Department of Public Health and the Program Director for the Master's in Public Health (MPH) degree.

Dr. Matthew N. Murray

Murray is the Director of the Howard H. Baker Jr. Center for Public Policy. He also is the Associate Director of the Boyd Center for Business and Economic Research and is a professor in the Department of Economics in the Haslam College of Business. He has led the team producing Tennessee's annual economic report to the governor since 1995.

Dr. Charles Sims

Sims is the Director of the Center's Energy & Environment program. He also is an associate professor in the Department of Economics in the Haslam College of Business. Sims has active research grants with the Sloan Foundation, USDA, and TVA. He has previously worked on projects involving invasive species and infectious diseases.

Howard H. Baker Jr Center for Public Policy
1640 Cumberland Avenue
Knoxville, TN 37996
Phone: 865-974-0931
Email: bakercenter@utk.edu
Online: bakercenter.utk.edu

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