As viruses spread, they tend to infect increasing numbers of people at high rates. The initial side of the curve over time, or rate of new infections, will naturally increase rapidly as more and more people are infected. If left unchecked, the total number people requiring health care will quickly rise well above the capacity of our US health care system.
By taking certain steps – canceling large public gatherings, for instance, and encouraging some people to restrict their contact with others – governments have a shot at stamping out new person-to-person transmissions, while also trying to mitigate the damage of the spread that isn’t under control.
The epidemic curve, a statistical chart used to visualize when and at what speed new cases are reported, could be flattened, rather than being allowed to rise exponentially. “If you look at the curves of outbreaks, they go into big peaks, and then come down. What we need to do is flatten that down,” stated Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases. “That would have less people infected. That would ultimately have less deaths. You do that by trying to interfere with the natural flow of the outbreak.”
The notion that the curve of this outbreak could be flattened began to gain credence after China took the extraordinary step of locking down tens of millions of people days in advance of the Lunar New Year, to prevent the virus from spreading around the country from Wuhan, the city where the outbreak appears to have started.
The quarantines, unprecedented in modern times, appear to have prevented explosive outbreaks from occurring in cities outside of Hubei province, where Wuhan is located.
Since then, spread of the virus in China has slowed to a trickle; the country reported only 19 cases on March 9th. And South Korea, which has had the third largest outbreak outside of China, also appears to be beating back transmission through aggressive actions. But other places, notably Italy and Iran, are struggling.
On any normal day, health systems in the United States typically run close to capacity. If a hospital is overwhelmed by Covid-19 cases, patients will have a lower chance of surviving than they would if they became ill when the hospital’s patient load was more manageable. People in car crashes, people with cancer, pregnant women who have complications during delivery – all those people risk getting a lesser caliber of care when a hospital is trying to cope with the chaos of an outbreak.
“I think the whole notion of flattening the curve is to slow things down so that this doesn’t hit us like a brick wall,” said Michael Mina, associate medical director of clinical microbiology at Boston’s Brigham and Women’s Hospital.
“It’s really all borne out of the risk of our health care infrastructure pulling apart at the seams if the virus spreads too quickly and too many people start showing up at the emergency room at any given time.”
The U.S. has about 2.8 hospital beds per 1,000 people (South Korea and Japan, two countries that have seemingly thwarted the exponential case growth trajectory, have more than 12 hospital beds per 1,000 people; even China has 4.3 per 1,000). With a population of 330 million, this is about 1 million hospital beds. At any given time, about 68% of them are occupied. That leaves about 300,000 beds available nationwide.
Most people with Covid-19 can be managed at home. But among 44,000 cases in China, about 15% required hospitalization and 5% ended up in critical care. In Italy, the statistics so far are even more dismal: More than half of infected individuals require hospitalization and about 10% need treatment in the ICU. As cases spiked, Italian hospitals quickly couldn’t keep up with the patients coming in.
Countries and regions that have been badly hit by the virus report hospitals that are utterly swamped by the influx of sick people struggling to breathe.
Alessandro Vespignani, director of the Network Science Institute at Northeastern University, is gravely worried about what he’s hearing from contacts in Italy, where people initially played down the outbreak as “a kind of flu”. Hospitals in the north of the country, which the virus first took root, are filled beyond capacity, he said.
By limiting exposure to others, also known as “social distancing“, epidemiologists believe the curve could be meaningfully flattened. Social distancing means avoiding contact with others. This is crucial from a global health perspective. Limiting coronavirus cases not only has the obvious benefit of keeping the elderly and vulnerable safe, but it lessens the single biggest public health issue: overwhelmed hospitals.