A tiny, microscopic virus like COVID-19 can begin in a single person and eventually spread to infect… [+] billions based on its transmission rate and the behaviors of people. We can mitigate or even stop it entirely, but only if drastic enough actions are taken in a timely fashion.
The COVID-19 coronavirus pandemic continues to spread around the world. As of today, more than 450,000 total cases of infection have been recorded, with the actual number likely being much higher due to the lack of sufficient testing. More than 20,000 of those infected have died, according to the latest statistics, with the total number of infections and the death rate both continuing to rise exponentially.
For the past few weeks, many (but not all) of us have been practicing social distancing, doing what we can to keep ourselves and our communities safe. However, against the recommendation of every major public health and medical organization, many are advocating that we end social distancing to better promote economic interests. Unfortunately, the science of disease-spread is very clear on this issue: ending social distancing for COVID-19 will create a worst-case scenario.
This March 17, 2020 photo shows an extraordinarily poor example of social distancing in action.… [+] Here, members of the White House administration gather in front of the press, gathering more than 10 people together while failing to keep a minimum separation of 6 feet between them, failing to adhere to even the basic ‘bare minimum’ CDC recommendations. (BRENDAN SMIALOWSKI/AFP via Getty Images)
Social distancing is a simple concept that is extremely useful, when widely well-implemented, at slowing the spread of an infectious disease. Applied to COVID-19, it includes these four steps:
- Not to come into contact with people outside of your home for any non-essential reason (essential reasons including things like obtaining food, medicine, and other necessary supplies).
- To leave your house as little as possible to accomplish these essential tasks (e.g., grocery shop once a week instead of daily).
- Not to come within 2 meters (approximately 6 feet) of others when you do leave your house.
- Not to participate in in-person gatherings at this time; restrictions on “numbers of people” are arbitrary, but zero is best.
If everyone adhered to these social distancing guidelines, the number of new infections would slow down to a trickle after a period of just a few weeks.
Three simple curves show how the number of COVID-19 cases will change depending on whether no action… [+] is taken (black), some social distancing measures are put into place (red), or whether a lockdown-style social isolation is imposed for 3-7 weeks (green). Note that the graph shows new infections, not total infections.
That’s the best-case scenario: the one where our behavioral changes can stop the spread of this novel coronavirus in its tracks.
On the other hand, if nobody followed these guidelines at all, the number of new infections would continue to rise exponentially, with the number of infected people doubling every few days. That’s the absolute worst-case scenario, where nobody changes their behavior at all.
What we’ve actually implemented thus far can best be described by the red curve above: mitigation. Many people are successfully practicing social distancing, but many others aren’t. People are still going to bars and restaurants; many people are keeping their businesses open; people are congregating in public and private spaces. In this case, we see a slightly slower exponential rise, but the number of cases still grows at this relentless pace.
The impact of timeliness on the total number of cases that occur in a given amount of time is… [+] heavily dependent on when an intervention occurs. For a 2.4 day doubling time (consistent with what US statistics show for COVID-19), an intervention that occurs on day 20 (red), day 22 (yellow), or day 25 (green) can lead to a dramatic change in the number of cases on day 50. The final numbers are 1394 cases (day 20 intervention), 1922 cases (day 22 intervention), 4292 cases (day 25 intervention), or 297,000 cases (no intervention). We are presently at more than 50,000 confirmed cases, making timely interventions more important and necessary than ever.
Right now, the United States has the third most total number of coronavirus cases in the world, behind only China and Italy, though it’s likely to pass both by the end of the week. If the current rate of exponential growth continues — the rate we’re currently seeing due to our current (insufficient) social distancing measures — then 10% of the United States, or approximately 30 million people, will be infected with COVID-19 by mid-April. Although other effects could help quench this rise even without additional interventions, this remains a fearsome worst-case scenario.
COVID-19 is already being touted, according to the MRC Centre for Global Infectious Disease Analysis, as the most serious public health threat in a respiratory virus since the 1918 H1N1 influenza pandemic. While there are a few people comparing COVID-19 to the typical flu, it is nothing of the sort. As Professor Akiko Iwasaki of Yale has stated, “COVID-19 is 30 times more deadly and almost two times more contagious than the flu. We have no existing immunity to COVID-19.”
A comparison of various deadly infectious diseases showcases how much more dangerous COVID-19 is… [+] than the standard flu: 30 times more deadly and more than twice the infection rate. The 1918 Spanish Flu, the worst pandemic in modern history, killed 675,000 residents of the United States. Without social distancing, COVID-19 will surpass that for certain later this year.
Akiko Iwasaki / Biorender
In an ideal world, what we’d be doing is performing widespread tests on everyone in the world to determine who has and doesn’t have COVID-19. People who tested positive would be quarantined, isolated and locked down, as would everyone that they came in contact with. If we could implement those measures, the number of new cases would drop the same way they rose: exponentially. But we don’t live in an ideal world.
From a disease control perspective, we have to work with the resources and information we have at our disposal today. We don’t have nearly the number of available tests necessary to successfully diagnose who has and doesn’t have COVID-19, and that’s a dealbreaker. In the absence of knowledge, we have to behave as though we’re all at risk. As stated very eloquently by Dr. Jen Totonchy, PhD in molecular microbiology and immunology, “we need to be doing more, sooner, to stop the spread of coronavirus.”
This graph shows the number of total COVID-19 cases as a fraction of the total population of a given… [+] country. Based on the current trajectories of the disease’s growth and spread, the United States is presently on track to reach a 10% infection rate by mid-April, faster than any other country in the world.
Andreas Burkert / cc-by-sa 4.0
The reason is simple:
- our healthcare system has only a fixed number of hospital beds,
- approximately 19% of people who get infected with COVID-19 require hospitalization,
- in countries where the healthcare system hasn’t been overloaded (like Taiwan and South Korea), the death rate is below 1%,
- but in countries where the healthcare system has been overloaded (like Italy), the death rate could be 8% or even higher.
If we were to remove all social distancing measures and travel restrictions, human mobility would ensure that exponential growth will continue for weeks to come, resulting in a minimum of tens of millions of infections in the United States alone. We are truly at risk of a worst-case scenario: where some 40-80% of the population gets infected with COVID-19 in the next few months, and 8% or more of them may die. With a total population exceeding 300 million, the United States could experience even more COVID-19 deaths than the CDC’s or the MRC Centre’s “worst case scenarios” of 1.7 and 2.2 million, respectively.
The disease curve will not remain an exponential forever, but will instead follow a shape known as a… [+] logistics curve. However, it is by controlling the spread of the disease during the exponential phase that we can most effectively reduce the death rate: by increasing the doubling time and reducing the rate of transmission of the disease. Social distancing practices are essential to this; removing them would steepen, rather than flatten, this curve.
Max Roser, Hannah Ritchie and Esteban Ortiz-Ospina (2020); OurWorldInData.org
There are a number of people talking about lifting the social distancing restrictions based on a specific calendar date, rather than according to the science of when it is safe to do so. Time periods as short as two weeks have been floated, which is wildly insufficient based on the current measures that have been taken. The idea is that this would help the economy, but all that would do is cause the health care system to collapse under the weight of COVID-19 cases. Tanking the health care industry, representing almost 20% of the United States’ GDP, will in no way save the economy.
According to Catherine Herzog, epidemiologist and disease oncologist, two weeks of isolation is insufficient to combat COVID-19, even if we perfectly self-quarantined and nobody came into contact with anyone outside of their homes during that time. “[After two weeks] some folks may just start showing symptoms then, and if we all start moving around again it will spread. We need to stop transmission more completely than that so it will take longer.” Each time we lift restrictions, she noted, new epidemics and outbreaks will ensue, as COVID-19 spreads newly through previously uninfected communities.
This photo, from just a few days ago at Daytona Beach, shows a large number of people gathered on… [+] the beach for spring break. Florida Governor Ron DeSantis has refused to order the state’s beaches closed as the number of COVID-19 cases increases across the state, against the recommendation of public health officials. (Paul Hennessy/SOPA Images/LightRocket via Getty Images)
Without sufficient testing available — and it isn’t, even for many people who are experiencing COVID-19 symptoms but not severely enough to require hospitalization — the safest option from a public health perspective would be an immediate and country-wide shelter-in-place order, or lockdown.
If everyone didn’t physically contact anyone else outside of their homes (and it literally takes everyone to make it effective) for a sufficient time period, we could successfully stop the exponential growth of COVID-19 deaths. As it stands right now, people as young as 17 are dying in the United States, and many bars, restaurants, non-essential businesses, churches, and public gathering spaces not only remain open, but busy as well. With each day that passes under the status quo, the number of cases in the United States increases by approximately 25% at present.
On March 1, 2020, there were only 30 confirmed cases of COVID-19 in the USA. By March 24, the most… [+] recent date that data was fully available at the time of publication, 53,659 cases have been confirmed, indicating exponential growth with a doubling time of less than 3 days.
COVID-19 Data Resource Hub
Dr. Anthony Fauci, the director of National Institute of Allergy and Infectious Diseases, has strongly recommended against going out in public for any non-essential reason. Speaking to Jon Cohen at Science, he stated very clearly,
[E]verybody in the country, at a minimum, should be following the fundamental guidelines. Elderly, stay out of society in self isolation. Don’t go to work if you don’t have to. […] No bars, no restaurants, no nothing. Only essential services. When you get a place like New York or Washington or California, you have got to ratchet it up.
There are strong arguments to be made for greater restrictions, with many states having already implemented stricter rules than the CDC’s minimum recommendations. The goal is to protect others and limit the number of deaths from this disease, and locking at-risk places down (and most places are now at-risk) is the most effective disease control strategy we have that’s implementable today.
The impact of successfully isolating the infected population (and keeping them away from the… [+] uninfected population) can play a tremendous role in slowing the spread of a disease. The four lines show the predicted effects of no isolation (blue), 50% successful isolation (red), 90% successful isolation (yellow), and 99% successful isolation (green).
The most important takeaway is this: COVID-19 is deadly, at least thirty times as deadly as the flu, and spreads easily and rapidly through an unrestricted population. The way we all lived our lives and publicly interacted with one another prior to March of 2020 is not a safe or sustainable way to live today, at perhaps the most critical time in this pandemic. Self-isolating as much as possible, to a much greater degree than we’re doing at present, is the best course of action we can presently make.
But if we remove our social isolation measures now, when we should be maximizing them more than ever, we’ll see tens of millions of Americans infected by mid-to-late April, with a substantial percentage of them very likely to die. The worst-case scenario can still be avoided, but only if we all act responsibly, and in the interest of the public good, right now.