The US has reported more than 101,000 coronavirus cases. Italy isn't far behind, with at least 86,000 cases; China has reported just under 82,000.
But the COVID-19 death rate — the number of deaths divided by the total number of cases — from these three hard-hit countries varies wildly.
The US's coronavirus death rate is currently 1.6%, which puts it among the lowest of any country with more than 9,000 cases. Italy's, by contrast, is 10.6% and China's is 4%.
The US has reported at least 1,500 deaths, Italy has reported more than 9,100, and China has nearly 3,300 as of Friday afternoon.
Countries' death rates change over time More than 593,000 people worldwide have been infected with the coronavirus, and at least 27,000 have died.
Because countries' case totals and death tolls are constantly changing, their death rates are not static — nor is the global rate. Instead, the rates fluctuate constantly as new cases and deaths get reported. They also depend on how many people get tested for COVID-19 (people whose cases aren't confirmed don't get included in the official case counts).
On Monday, for example, the US's death rate was 1.2% and Italy's was 9.5%. Both are now higher.
A recent study (which has yet to be peer-reviewed) from a group of Chinese researchers suggested the rate could be lower there than the country's numbers reflect: Researchers found that the probability of a person dying after developing symptoms was about 1.4% in Wuhan, China.
A shifting global death rate As of Friday, the global coronavirus death rate hovered around 4.6%, according to data from Johns Hopkins — that's higher than the World Health Organization's March 3 estimate of about 3.4%.
Some health experts have predicted that death rates overall will decrease as the number of cases rises and testing expands. The US's experience offers some evidence of that: Between March 6 and 27, the country's death rate dropped from 5.9% to 1.6%; the number of people tested in the US jumped to more than 626,000 from fewer than 2,000 over that time period.
Widespread testing could mean a lower death rate because most COVID-19 cases — about 80%, according to one study — are considered mild. Often, the cases tested and reported first are those with severe symptoms, since those people go to the hospital. Milder cases, on the other hand, could go uncounted or get reported later on, so the true number of infected people is likely much higher than the reported total.
The death rate of a disease is different from its mortality rate — the latter is the number of deaths out of the number of people in an at-risk population. A death rate is not a reflection of the likelihood that a given person will die.
The White House approved Michigan’s request for an emergency declaration Saturday, after a week of contentious public feuding between President Donald Trump and the state's governor over measures to combat the coronavirus.
The squabble between Trump and Gov. Gretchen Whitmer, which has played out across Twitter, cable news and radio airwaves, has been one of several conflicts simmering between Trump and governors who have criticized the federal response to the pandemic — and then seen Trump return fire online or in his press briefings.
Governors across the country, including Whitmer, have repeatedly called on Trump to use the Defense Production Act to force private companies to manufacture life-saving medical supplies, including protective hospital masks and ventilators. Governors have also clashed with Trump about state-imposed lock-downs and travel bans.
Whitmer — a first-term governor who in February delivered the Democrats' response to Trump's State of the Union address — charged in an interview Friday morning that Trump’s actions have prevented her state from getting the equipment it needs.
“What I’ve gotten back is that vendors with whom we’ve procured contracts — they’re being told not to send stuff to Michigan,” Whitmer told Detroit’s WWJ 950. “It’s really concerning. I reached out to the White House last night and asked for a phone call with the president, ironically at the time this stuff was going on.”
Trump first invoked the DPA later Friday following escalating public criticism of General Motors, after the White House and company failed to reach a deal to build ventilators.
Watch live coverage as President Trump and the coronavirus task force give an update on the response effort from the White House.
On a special edition of Meet the Press, White House Coronavirus Response Coordinator Dr. Deborah Birx said it is important to react quickly because no state or metro area will be spared from this virus. Gov. John Bel Edwards (D-La.) and Gov. Gretchen Whitmer (D-Mich.) discuss the difficulties their states face as cases rise exponentially. Former VP Joe Biden explains how he would handle this crisis if he were president. Andrea Mitchell, Eugene Robinson, Hugh Hewitt and Carol Lee join the panel.
Abandoning his hope that the country could end its lockdown restrictions by Easter, which will be celebrated in two weeks, President Trump said on Sunday that intensive measures to combat the coronavirus pandemic would continue until the end of April.
“The modeling estimates that the peak in death rate is likely to hit in two weeks,” Trump said, referencing epidemiological models of how the disease will spread across the United States. “Therefore, we will be extending our guidelines to April 30, to slow the spread.”
The president added that on Tuesday, his administration would make public “a summary of our findings, supporting data and strategy” regarding the ongoing battle against the disease.
Trump announced the new policy at the daily coronavirus task force briefing, which was held in the Rose Garden on what turned out to be a pleasant spring evening in the nation’s capital. “Nothing would be worse than declaring victory before the victory is won,” Trump said. As recently as last week, he signalled his impatience with the 15 Days to Slow the Spread guidelines that had been recommended by the Centers for Disease Control and Prevention.
Those guidelines call for Americans to work from home and avoid social situations, as well as unnecessary travel. While public health officials believe it is necessary to keep such measures in place for the next two or three months, some of the president’s advisers — and the president himself — worry about the economic effects of 328 million people living in lockdown.
In an interview with Fox News last week, Trump worried that the coronavirus response could be more harmful than the coronavirus itself, which has so far killed about 2,000 Americans. “I would love to have the country opened up and just raring to go by Easter,” he said.
Turbulent Gas Clouds and Respiratory Pathogen Emissions Potential Implications for Reducing Transmission of COVID-19 Lydia Bourouiba, PhD1
Te current coronavirus disease 2019 (COVID-19) outbreak vividly demonstrates the burden that respiratory infectious diseases impose in an intimately connected world. Unprecedented containment and mitigation policies have been implemented in an effort to limit the spread of COVID-19, including travel restrictions, screening and testing of travelers, isolation and quarantine, and school closures.
A key goal of such policies is to decrease the encounters between infected individuals and susceptible individuals and decelerate the rate of transmission. Although such social distancing strategies are critical in the current time of pandemic, it may seem surprising that the current understanding of the routes of host-to-host transmission in respiratory infectious diseases are predicated on a model of disease transmission developed in the 1930s that, by modern standards, seems overly simplified. Implementing public health recommendations based on these older models may limit the effectiveness of the proposed interventions.
In 1897, Carl Flügge showed that pathogens were present in expiratory droplets large enough to settle around an infected individual. “Droplet transmission” by contact with the ejected and infected fluid phase of droplets was thought to be the primary route for respiratory transmission of diseases. This view prevailed until William F. Wells focused on tuberculosis transmission in the 1930s and dichotomized respiratory droplet emissions into “large” and “small” droplets.
According to Wells, isolated droplets are emitted upon exhalation. Large droplets settle faster than they evaporate, contaminating the immediate vicinity of the infected individual. In contrast, small droplets evaporate faster than they settle. In this model, as small droplets transition from the warm and moist conditions of the respiratory system to the colder and drier outside environment, they evaporate and form residual particulates made of the dried material from the original droplets. These residual particulates are referred to as droplet nuclei or aerosols. These ideas resulted in a dichotomous classification between large vs small droplets, or droplets vs aerosol, which can then mediate transmission of respiratory disease. Infection control strategies were then developed based on whether a respiratory infectious disease is primarily transmitted via the large or the small droplet route.
The dichotomy of large vs small droplets remains at the core of the classification systems of routes of respiratory disease transmission adopted by the World Health Organization and other agencies, such as the Centers for Disease Control and Prevention. These classification systems employ various arbitrary droplet diameter cutoffs, from 5 to 10 μm, to categorize host-to-host transmission as droplets or aerosol routes.1 Such dichotomies continue to underly current risk management, major recommendations, and allocation of resources for response management associated with infection control, including for COVID-19. Even when maximum containment policies were enforced, the rapid international spread of COVID-19 suggests that using arbitrary droplet size cutoffs may not accurately reflect what actually occurs with respiratory emissions, possibly contributing to the ineffectiveness of some procedures used to limit the spread of respiratory disease.
New Model for Respiratory Emissions
Recent work has demonstrated that exhalations, sneezes, and coughs not only consist of mucosalivary droplets following short-range semiballistic emission trajectories but, importantly, are primarily made of a multiphase turbulent gas (a puff) cloud that entrains ambient air and traps and carries within it clusters of droplets with a continuum of droplet sizes (Figure; Video).2,3 The locally moist and warm atmosphere within the turbulent gas cloud allows the contained droplets to evade evaporation for much longer than occurs with isolated droplets. Under these conditions, the lifetime of a droplet could be considerably extended by a factor of up to 1000, from a fraction of a second to minutes.
Figure. Multiphase Turbulent Gas Cloud From a Human Sneeze
Owing to the forward momentum of the cloud, pathogen-bearing droplets are propelled much farther than if they were emitted in isolation without a turbulent puff cloud trapping and carrying them forward. Given various combinations of an individual patient’s physiology and environmental conditions, such as humidity and temperature, the gas cloud and its payload of pathogen-bearing droplets of all sizes can travel 23 to 27 feet (7-8 m).3,4 Importantly, the range of all droplets, large and small, is extended through their interaction with and trapping within the turbulent gas cloud, compared with the commonly accepted dichotomized droplet model that does not account for the possibility of a hot and moist gas cloud. Moreover, throughout the trajectory, droplets of all sizes settle out or evaporate at rates that depend not only on their size, but also on the degree of turbulence and speed of the gas cloud, coupled with the properties of the ambient environment (temperature, humidity, and airflow).
Droplets that settle along the trajectory can contaminate surfaces, while the rest remain trapped and clustered in the moving cloud. Eventually the cloud and its droplet payload lose momentum and coherence, and the remaining droplets within the cloud evaporate, producing residues or droplet nuclei that may stay suspended in the air for hours, following airflow patterns imposed by ventilation or climate-control systems. The evaporation of pathogen-laden droplets in complex biological fluids is poorly understood. The degree and rate of evaporation depend strongly on ambient temperature and humidity conditions, but also on the inner dynamics of the turbulent puff cloud coupled with the composition of the liquid exhaled by the patient.
A 2020 report from China demonstrated that severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus particles could be found in the ventilation systems in hospital rooms of patients with COVID-19.5 Finding virus particles in these systems is more consistent with the turbulent gas cloud hypothesis of disease transmission than the dichotomous model because it explains how viable virus particles can travel long distances from patients. Whether these data have clinical implications with respect to COVID-19 is unknown.
Implications for Prevention and Precaution
Although no studies have directly evaluated the biophysics of droplets and gas cloud formation for patients infected with the SARS-CoV-2 virus, several properties of the exhaled gas cloud and respiratory transmission may apply to this pathogen. If so, this possibility may influence current recommendations intended to minimize the risk for disease transmission. In the latest World Health Organization recommendations for COVID-19, health care personnel and other staff are advised to maintain a 3-foot (1-m)6 distance away from a person showing symptoms of disease, such as coughing and sneezing. The Centers for Disease Control and Prevention recommends a 6-foot (2-m) separation.7,8 However, these distances are based on estimates of range that have not considered the possible presence of a high-momentum cloud carrying the droplets long distances. Given the turbulent puff cloud dynamic model, recommendations for separations of 3 to 6 feet (1-2 m) may underestimate the distance, timescale, and persistence over which the cloud and its pathogenic payload travel, thus generating an underappreciated potential exposure range for a health care worker. For these and other reasons, wearing of appropriate personal protection equipment is vitally important for health care workers caring for patients who may be infected, even if they are farther than 6 feet away from a patient.
Turbulent gas cloud dynamics should influence the design and recommended use of surgical and other masks. These masks can be used both for source control (ie, reducing spread from an infected person) and for protection of the wearer (ie, preventing spread to an unaffected person). The protective efficacy of N95 masks depends on their ability to filter incoming air from aerosolized droplet nuclei. However, these masks are only designed for a certain range of environmental and local conditions and a limited duration of usage.9 Mask efficacy as source control depends on the ability of the mask to trap or alter the high-momentum gas cloud emission with its pathogenic payload. Peak exhalation speeds can reach up to 33 to 100 feet per second (10-30 m/s), creating a cloud that can span approximately 23 to 27 feet (7-8 m). Protective and source control masks, as well as other protective equipment, should have the ability to repeatedly withstand the kind of high-momentum multiphase turbulent gas cloud that may be ejected during a sneeze or a cough and the exposure from them. Currently used surgical and N95 masks are not tested for these potential characteristics of respiratory emissions.
There is a need to understand the biophysics of host-to-host respiratory disease transmission accounting for in-host physiology, pathogenesis, and epidemiological spread of disease. The rapid spread of COVID-19 highlights the need to better understand the dynamics of respiratory disease transmission by better characterizing transmission routes, the role of patient physiology in shaping them, and best approaches for source control to potentially improve protection of front-line workers and prevent disease from spreading to the most vulnerable members of the population.
Published Online: March 26, 2020. doi:10.1001/jama.2020.4756