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Flattening the Coronavirus Curve Flattening the Coronavirus Curve
(about 4 hours later)
At the end of February, Drew Harris, a population health analyst at Thomas Jefferson University in Philadelphia, had just flown across the country to visit his daughter in Eugene, Ore., when he saw an article on his Google news feed. It was from The Economist, and was about limiting the damage of the coronavirus.At the end of February, Drew Harris, a population health analyst at Thomas Jefferson University in Philadelphia, had just flown across the country to visit his daughter in Eugene, Ore., when he saw an article on his Google news feed. It was from The Economist, and was about limiting the damage of the coronavirus.
The accompanying art, by the visual-data journalist Rosamund Pearce, based on a graphic that had appeared in a C.D.C. paper titled “Community Mitigation Guidelines to Prevent Pandemic Influenza,” showed what Dr. Harris called two epi curves. One had a steep peak indicating a surge of coronavirus outbreak in the near term; the other had a flatter slope, indicating a more gradual rate of infection over a longer period of time.The accompanying art, by the visual-data journalist Rosamund Pearce, based on a graphic that had appeared in a C.D.C. paper titled “Community Mitigation Guidelines to Prevent Pandemic Influenza,” showed what Dr. Harris called two epi curves. One had a steep peak indicating a surge of coronavirus outbreak in the near term; the other had a flatter slope, indicating a more gradual rate of infection over a longer period of time.
The gentler curve results in fewer people infected at this critical moment in time — preventing a surge that would inundate the healthcare system and ultimately, one hopes, resulting in fewer deaths. “What we need to do is flatten that down,” said Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, during the coronavirus task force briefing at the White House on a Tuesday evening in early March. “You do that with trying to interfere with the natural flow of the outbreak.”The gentler curve results in fewer people infected at this critical moment in time — preventing a surge that would inundate the healthcare system and ultimately, one hopes, resulting in fewer deaths. “What we need to do is flatten that down,” said Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, during the coronavirus task force briefing at the White House on a Tuesday evening in early March. “You do that with trying to interfere with the natural flow of the outbreak.”
The infographic reminded Dr. Harris of something similar that he had designed years earlier for a pandemic preparedness training program. “Folks in the preparedness and public health community have been thinking about all of these issues for many years,” Dr. Harris said in an email. “Understanding and managing surge is an important part of preparedness.” But during the training course, Dr. Harris’s students had struggled with the concept of reducing the epidemic curve, so he added a dotted line indicating hospital capacity — “to make clear what was at stake,” he said.The infographic reminded Dr. Harris of something similar that he had designed years earlier for a pandemic preparedness training program. “Folks in the preparedness and public health community have been thinking about all of these issues for many years,” Dr. Harris said in an email. “Understanding and managing surge is an important part of preparedness.” But during the training course, Dr. Harris’s students had struggled with the concept of reducing the epidemic curve, so he added a dotted line indicating hospital capacity — “to make clear what was at stake,” he said.
After his visit with his daughter, Dr. Harris was waiting for his return flight in Portland when the first Oregon coronavirus case was announced; he had dinner at a busy airport bar and thought about how quiet the place would be in a week or two when the reality of the outbreak set in. Once home, he recreated his graphic and posted it on Twitter and LinkedIn, and was pleased to see the enthusiastic interest in flattening the curve.After his visit with his daughter, Dr. Harris was waiting for his return flight in Portland when the first Oregon coronavirus case was announced; he had dinner at a busy airport bar and thought about how quiet the place would be in a week or two when the reality of the outbreak set in. Once home, he recreated his graphic and posted it on Twitter and LinkedIn, and was pleased to see the enthusiastic interest in flattening the curve.
“Now I know what going viral means,” Dr. Harris said. (For a more detailed analysis, see a recent paper in The Lancet, “How will country-based mitigation measures influence the course of the COVID-19 epidemic?”)“Now I know what going viral means,” Dr. Harris said. (For a more detailed analysis, see a recent paper in The Lancet, “How will country-based mitigation measures influence the course of the COVID-19 epidemic?”)
The following is an edited version of our email conversation.The following is an edited version of our email conversation.
The ideal goal in fighting an epidemic or pandemic is to completely halt the spread. But merely slowing it — mitigation — is critical. This reduces the number of cases that are active at any given time, which in turn gives doctors, hospitals, police, schools and vaccine-manufacturers time to prepare and respond, without becoming overwhelmed. Most hospitals can function with 10 percent reduction in staff, but not with half their people out at once.The ideal goal in fighting an epidemic or pandemic is to completely halt the spread. But merely slowing it — mitigation — is critical. This reduces the number of cases that are active at any given time, which in turn gives doctors, hospitals, police, schools and vaccine-manufacturers time to prepare and respond, without becoming overwhelmed. Most hospitals can function with 10 percent reduction in staff, but not with half their people out at once.
Some commentators have argued for getting the outbreak over with quickly. That is a recipe for panic, unnecessary suffering and death. Slowing and spreading out the tidal wave of cases will save lives. Flattening the curve keeps society going.Some commentators have argued for getting the outbreak over with quickly. That is a recipe for panic, unnecessary suffering and death. Slowing and spreading out the tidal wave of cases will save lives. Flattening the curve keeps society going.
Both curves add up the number of new cases over time. The more people reporting with the virus on a given day, the higher the curve; a high curve means the virus is spreading fast. A low curve shows that the virus is spreading slower — fewer people are diagnosed with the disease on any given day. Keeping the curve down — diminishing the rate at which new cases occur — prevents overtaxing the finite resources (represented by the dotted line) available to treat it.Both curves add up the number of new cases over time. The more people reporting with the virus on a given day, the higher the curve; a high curve means the virus is spreading fast. A low curve shows that the virus is spreading slower — fewer people are diagnosed with the disease on any given day. Keeping the curve down — diminishing the rate at which new cases occur — prevents overtaxing the finite resources (represented by the dotted line) available to treat it.
Think of the health care system capacity as a subway car that can only hold so many people at once. During rush hour, that capacity is not enough to handle the demand, so people must wait on the platform for their turn to ride. Staggering work hours diminishes the rush hour and increases the likelihood that you will get on the train and maybe even get a seat. Avoiding a surge of coronavirus cases can ensure that anyone who needs care will find it at the hospital.Think of the health care system capacity as a subway car that can only hold so many people at once. During rush hour, that capacity is not enough to handle the demand, so people must wait on the platform for their turn to ride. Staggering work hours diminishes the rush hour and increases the likelihood that you will get on the train and maybe even get a seat. Avoiding a surge of coronavirus cases can ensure that anyone who needs care will find it at the hospital.
Diseases spread when one person gives it to one or more others, who go on to give it to more people, and so on. How fast this occurs depends on many factors, including how contagious the disease is, how many people are vulnerable and how quickly they get sick.Diseases spread when one person gives it to one or more others, who go on to give it to more people, and so on. How fast this occurs depends on many factors, including how contagious the disease is, how many people are vulnerable and how quickly they get sick.
The difference between seasonal flu and coronavirus is that many people have full or partial immunity to the flu virus because they have had it before or were vaccinated against it. Far more people are vulnerable to coronavirus, so it has many more targets of opportunity to spread. Keeping people apart in time and space with social distancing measures, self-isolation and actual quarantine decreases opportunities for transmission.The difference between seasonal flu and coronavirus is that many people have full or partial immunity to the flu virus because they have had it before or were vaccinated against it. Far more people are vulnerable to coronavirus, so it has many more targets of opportunity to spread. Keeping people apart in time and space with social distancing measures, self-isolation and actual quarantine decreases opportunities for transmission.
To take the subway example again, a packed car — or a packed subway platform — is a great place to spread the virus. But reducing the number of people on the train or platform, by asking people to work from home or to stagger their working hours, enables individuals to stay farther apart, limiting the spread of the virus. That is social distancing in action.To take the subway example again, a packed car — or a packed subway platform — is a great place to spread the virus. But reducing the number of people on the train or platform, by asking people to work from home or to stagger their working hours, enables individuals to stay farther apart, limiting the spread of the virus. That is social distancing in action.
Updated June 22, 2020 Updated June 24, 2020
Scientists around the country have tried to identify everyday materials that do a good job of filtering microscopic particles. In recent tests, HEPA furnace filters scored high, as did vacuum cleaner bags, fabric similar to flannel pajamas and those of 600-count pillowcases. Other materials tested included layered coffee filters and scarves and bandannas. These scored lower, but still captured a small percentage of particles.
A commentary published this month on the website of the British Journal of Sports Medicine points out that covering your face during exercise “comes with issues of potential breathing restriction and discomfort” and requires “balancing benefits versus possible adverse events.” Masks do alter exercise, says Cedric X. Bryant, the president and chief science officer of the American Council on Exercise, a nonprofit organization that funds exercise research and certifies fitness professionals. “In my personal experience,” he says, “heart rates are higher at the same relative intensity when you wear a mask.” Some people also could experience lightheadedness during familiar workouts while masked, says Len Kravitz, a professor of exercise science at the University of New Mexico.A commentary published this month on the website of the British Journal of Sports Medicine points out that covering your face during exercise “comes with issues of potential breathing restriction and discomfort” and requires “balancing benefits versus possible adverse events.” Masks do alter exercise, says Cedric X. Bryant, the president and chief science officer of the American Council on Exercise, a nonprofit organization that funds exercise research and certifies fitness professionals. “In my personal experience,” he says, “heart rates are higher at the same relative intensity when you wear a mask.” Some people also could experience lightheadedness during familiar workouts while masked, says Len Kravitz, a professor of exercise science at the University of New Mexico.
The steroid, dexamethasone, is the first treatment shown to reduce mortality in severely ill patients, according to scientists in Britain. The drug appears to reduce inflammation caused by the immune system, protecting the tissues. In the study, dexamethasone reduced deaths of patients on ventilators by one-third, and deaths of patients on oxygen by one-fifth.The steroid, dexamethasone, is the first treatment shown to reduce mortality in severely ill patients, according to scientists in Britain. The drug appears to reduce inflammation caused by the immune system, protecting the tissues. In the study, dexamethasone reduced deaths of patients on ventilators by one-third, and deaths of patients on oxygen by one-fifth.
The coronavirus emergency relief package gives many American workers paid leave if they need to take time off because of the virus. It gives qualified workers two weeks of paid sick leave if they are ill, quarantined or seeking diagnosis or preventive care for coronavirus, or if they are caring for sick family members. It gives 12 weeks of paid leave to people caring for children whose schools are closed or whose child care provider is unavailable because of the coronavirus. It is the first time the United States has had widespread federally mandated paid leave, and includes people who don’t typically get such benefits, like part-time and gig economy workers. But the measure excludes at least half of private-sector workers, including those at the country’s largest employers, and gives small employers significant leeway to deny leave.The coronavirus emergency relief package gives many American workers paid leave if they need to take time off because of the virus. It gives qualified workers two weeks of paid sick leave if they are ill, quarantined or seeking diagnosis or preventive care for coronavirus, or if they are caring for sick family members. It gives 12 weeks of paid leave to people caring for children whose schools are closed or whose child care provider is unavailable because of the coronavirus. It is the first time the United States has had widespread federally mandated paid leave, and includes people who don’t typically get such benefits, like part-time and gig economy workers. But the measure excludes at least half of private-sector workers, including those at the country’s largest employers, and gives small employers significant leeway to deny leave.
So far, the evidence seems to show it does. A widely cited paper published in April suggests that people are most infectious about two days before the onset of coronavirus symptoms and estimated that 44 percent of new infections were a result of transmission from people who were not yet showing symptoms. Recently, a top expert at the World Health Organization stated that transmission of the coronavirus by people who did not have symptoms was “very rare,” but she later walked back that statement.So far, the evidence seems to show it does. A widely cited paper published in April suggests that people are most infectious about two days before the onset of coronavirus symptoms and estimated that 44 percent of new infections were a result of transmission from people who were not yet showing symptoms. Recently, a top expert at the World Health Organization stated that transmission of the coronavirus by people who did not have symptoms was “very rare,” but she later walked back that statement.
Touching contaminated objects and then infecting ourselves with the germs is not typically how the virus spreads. But it can happen. A number of studies of flu, rhinovirus, coronavirus and other microbes have shown that respiratory illnesses, including the new coronavirus, can spread by touching contaminated surfaces, particularly in places like day care centers, offices and hospitals. But a long chain of events has to happen for the disease to spread that way. The best way to protect yourself from coronavirus — whether it’s surface transmission or close human contact — is still social distancing, washing your hands, not touching your face and wearing masks.Touching contaminated objects and then infecting ourselves with the germs is not typically how the virus spreads. But it can happen. A number of studies of flu, rhinovirus, coronavirus and other microbes have shown that respiratory illnesses, including the new coronavirus, can spread by touching contaminated surfaces, particularly in places like day care centers, offices and hospitals. But a long chain of events has to happen for the disease to spread that way. The best way to protect yourself from coronavirus — whether it’s surface transmission or close human contact — is still social distancing, washing your hands, not touching your face and wearing masks.
A study by European scientists is the first to document a strong statistical link between genetic variations and Covid-19, the illness caused by the coronavirus. Having Type A blood was linked to a 50 percent increase in the likelihood that a patient would need to get oxygen or to go on a ventilator, according to the new study.A study by European scientists is the first to document a strong statistical link between genetic variations and Covid-19, the illness caused by the coronavirus. Having Type A blood was linked to a 50 percent increase in the likelihood that a patient would need to get oxygen or to go on a ventilator, according to the new study.
The unemployment rate fell to 13.3 percent in May, the Labor Department said on June 5, an unexpected improvement in the nation’s job market as hiring rebounded faster than economists expected. Economists had forecast the unemployment rate to increase to as much as 20 percent, after it hit 14.7 percent in April, which was the highest since the government began keeping official statistics after World War II. But the unemployment rate dipped instead, with employers adding 2.5 million jobs, after more than 20 million jobs were lost in April.The unemployment rate fell to 13.3 percent in May, the Labor Department said on June 5, an unexpected improvement in the nation’s job market as hiring rebounded faster than economists expected. Economists had forecast the unemployment rate to increase to as much as 20 percent, after it hit 14.7 percent in April, which was the highest since the government began keeping official statistics after World War II. But the unemployment rate dipped instead, with employers adding 2.5 million jobs, after more than 20 million jobs were lost in April.
States are reopening bit by bit. This means that more public spaces are available for use and more and more businesses are being allowed to open again. The federal government is largely leaving the decision up to states, and some state leaders are leaving the decision up to local authorities. Even if you aren’t being told to stay at home, it’s still a good idea to limit trips outside and your interaction with other people.
Common symptoms include fever, a dry cough, fatigue and difficulty breathing or shortness of breath. Some of these symptoms overlap with those of the flu, making detection difficult, but runny noses and stuffy sinuses are less common. The C.D.C. has also added chills, muscle pain, sore throat, headache and a new loss of the sense of taste or smell as symptoms to look out for. Most people fall ill five to seven days after exposure, but symptoms may appear in as few as two days or as many as 14 days.Common symptoms include fever, a dry cough, fatigue and difficulty breathing or shortness of breath. Some of these symptoms overlap with those of the flu, making detection difficult, but runny noses and stuffy sinuses are less common. The C.D.C. has also added chills, muscle pain, sore throat, headache and a new loss of the sense of taste or smell as symptoms to look out for. Most people fall ill five to seven days after exposure, but symptoms may appear in as few as two days or as many as 14 days.
If air travel is unavoidable, there are some steps you can take to protect yourself. Most important: Wash your hands often, and stop touching your face. If possible, choose a window seat. A study from Emory University found that during flu season, the safest place to sit on a plane is by a window, as people sitting in window seats had less contact with potentially sick people. Disinfect hard surfaces. When you get to your seat and your hands are clean, use disinfecting wipes to clean the hard surfaces at your seat like the head and arm rest, the seatbelt buckle, the remote, screen, seat back pocket and the tray table. If the seat is hard and nonporous or leather or pleather, you can wipe that down, too. (Using wipes on upholstered seats could lead to a wet seat and spreading of germs rather than killing them.)If air travel is unavoidable, there are some steps you can take to protect yourself. Most important: Wash your hands often, and stop touching your face. If possible, choose a window seat. A study from Emory University found that during flu season, the safest place to sit on a plane is by a window, as people sitting in window seats had less contact with potentially sick people. Disinfect hard surfaces. When you get to your seat and your hands are clean, use disinfecting wipes to clean the hard surfaces at your seat like the head and arm rest, the seatbelt buckle, the remote, screen, seat back pocket and the tray table. If the seat is hard and nonporous or leather or pleather, you can wipe that down, too. (Using wipes on upholstered seats could lead to a wet seat and spreading of germs rather than killing them.)
If you’ve been exposed to the coronavirus or think you have, and have a fever or symptoms like a cough or difficulty breathing, call a doctor. They should give you advice on whether you should be tested, how to get tested, and how to seek medical treatment without potentially infecting or exposing others.If you’ve been exposed to the coronavirus or think you have, and have a fever or symptoms like a cough or difficulty breathing, call a doctor. They should give you advice on whether you should be tested, how to get tested, and how to seek medical treatment without potentially infecting or exposing others.
If you’re sick and you think you’ve been exposed to the new coronavirus, the C.D.C. recommends that you call your healthcare provider and explain your symptoms and fears. They will decide if you need to be tested. Keep in mind that there’s a chance — because of a lack of testing kits or because you’re asymptomatic, for instance — you won’t be able to get tested.
Mitigation efforts keep people farther apart, making every transmission opportunity marginally less likely. This slows the spread. We should, and will, take the most vulnerable people out of the population altogether by keeping them totally separate. This is what Washington State is trying to do by limiting visitors to nursing homes. Think of this as a reverse quarantine.Mitigation efforts keep people farther apart, making every transmission opportunity marginally less likely. This slows the spread. We should, and will, take the most vulnerable people out of the population altogether by keeping them totally separate. This is what Washington State is trying to do by limiting visitors to nursing homes. Think of this as a reverse quarantine.
Like most everyone else, I’m more aware of my surroundings and behaviors. I try to use a sleeve or elbow to open doors, and I wash my hands or use hand sanitizers after I touch a surface that might be contaminated. And I made sure to have a good supply of my prescription and nonprescription medications, just in case any shortages occur after the shutdown of Chinese pharmaceutical suppliers. I’m following the lead of my public health officials here in Philadelphia, where there is only one case as of Tuesday, and travel isn’t restricted. I’m avoiding crowds and sick people. I am going out, and will continue to do so unless a quarantine is ordered or public places are closed.Like most everyone else, I’m more aware of my surroundings and behaviors. I try to use a sleeve or elbow to open doors, and I wash my hands or use hand sanitizers after I touch a surface that might be contaminated. And I made sure to have a good supply of my prescription and nonprescription medications, just in case any shortages occur after the shutdown of Chinese pharmaceutical suppliers. I’m following the lead of my public health officials here in Philadelphia, where there is only one case as of Tuesday, and travel isn’t restricted. I’m avoiding crowds and sick people. I am going out, and will continue to do so unless a quarantine is ordered or public places are closed.
I know there is a good chance that I will catch the virus before a vaccine becomes available, but I also believe I’m very likely to do fine. I’m not in any high-risk group. But I worry about the more vulnerable folks and want to do what I can to prevent the spread. I also worry about people who lack the resources I have. What happens to the self-employed, hourly workers and people in the gig economy when business stops? What about the homeless who depend upon charity and services for support? It’s these second-order effects that could be just as devastating if this epidemic really takes off.I know there is a good chance that I will catch the virus before a vaccine becomes available, but I also believe I’m very likely to do fine. I’m not in any high-risk group. But I worry about the more vulnerable folks and want to do what I can to prevent the spread. I also worry about people who lack the resources I have. What happens to the self-employed, hourly workers and people in the gig economy when business stops? What about the homeless who depend upon charity and services for support? It’s these second-order effects that could be just as devastating if this epidemic really takes off.
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