Content Reviewers:Ursula Florjanczyk, MS, Evan Debevec-McKenney, Kaylee Neff, Yifan Xiao, MD, Viviana Popa, MD, Rishi Desai, MD, MPH
COVID-19 is caused by a virus called SARS CoV-2, or severe acute respiratory syndrome coronavirus 2, because it’s genetically similar to the SARS coronavirus which was responsible for the SARS outbreak in 2002.
Now, coronaviruses that circulate among humans are typically benign, and they cause about a quarter of all common cold illnesses.
In COVID-19 what happened is that there was a coronaviruses initially circulating among bats, which are a natural animal reservoir, that seems to have mutated and ultimately started causing disease in humans.
The outbreak began in China, but has since spread around the world.
Worldwide, as of August 1st 2020, or roughly 8months into the outbreak, there have been about 18 million confirmed cases of COVID-19 and 681 thousand deaths, resulting in a fatality rate of approximately 4%.
However, current studies suggest that the actual fatality rate is likely to be lower, around 0.7%.
The reason for this is that there are a lot of undiagnosed COVID 19 cases which makes the actual number of cases go up.
Many of these are asymptomatic carriers; in fact the National Institute of Allergy and Infectious Diseases, has estimated that 25 to 50 % of the cases may remain asymptomatic.
During this worldwide pandemic, there are many lessons to be learned from how different countries have responded to the disease.
To explore that, let’s use an epidemic curve which shows the number of new cases in a country seen each day.
The horizontal line represents the capacity of the healthcare system within that country.
Health care capacity accounts for things like the number of beds and ventilators as well as the number of healthcare workers and resources like personal protective equipment or PPE they have available.
Usually, the healthcare system is working near full capacity, so when a pandemic like COVID-19 breaks out, even a relatively small increase in the number of patients can overwhelm the healthcare system.
So the 2 strategies to tackle this problem are to flatten the curve and raise the line.
Flattening the curve is focused on diminishing the total number of people that get sick and slows down the rate at which new people get sick, while raising the line helps to actually increase healthcare capacity.
Let’s take a look at how different countries apply these two strategies, starting with China, the first country to deal with COVID 19.
China informed the World Health Organization about COVID-19 on Dec 31, 2019.
A few weeks later, on January 24th, China aggressively tried to flatten the curve by placing a major lock down in the Hubei province, and then issued a similar lockdown in other regions within China.
Authorities forced residents to stay at home except for essential activities like going to the pharmacy or getting groceries.
Non-essential businesses and schools were shut down, public transportations was shut down, and roads between cities were blocked off.
Going even further, some communities enforced a system by which there was only one entrance and exit and everyone passing through was screened for symptoms of COVID 19.
If anyone in the community tested positive, the entire community might be quarantined.
In all, this affected 15 cities and about 57 million people.
The measures were swiftly enacted and strictly enforced, and twelve days later, on February 5th, the exponential growth broke and the number of new cases started to fall off.
Meanwhile given how many cases there already were at that point, China made efforts to raise the line.
They built multiple hospitals dedicated to COVID-19 patients, and flew in doctors and nurses from less affected regions of the country to staff these hospitals and kept them protected with well designed PPE that covered them from head to toe.
By March, the economy began to return to normal and China was seeing more cases of COVID-19 from travelers then from their citizens.
Now, let’s look at South Korea, which took a slightly different, yet equally effective strategy.
To flatten the curve, they implemented mass testing that was free, easy, and accessible.
They offered drive-through testing stations, where people were tested inside their car.
They also had phone booth-like testing areas where the person walks in, gets tested, and walks out.
South Korea was performing 15,000 tests per day and by July 29th, they had tested around 1,547,307 people out of a population of 51 million, which works out to 1 out of 33 people.
People who tested positive were either sent to a hospital if their symptoms were severe, or to a quarantine facility if the symptoms were more mild.
At the same time public health workers conducted contact tracing for every case, to track down individuals that might have been exposed to the virus.
Because South Korea had such a thorough understanding of who did and didn’t have COVID-19, and where they had been, the lockdown was effectively done at the level of the sick individual, rather than at the societal level like in China.
Given the forewarning that South Korea had about the disease and the aggressive efforts around case-identification, their healthcare system was well prepared for the patients and had the resources to keep healthcare workers safe.
Next, let’s look at the United States which has the most cases in the entire world and where the number of cases continues to rise quickly.
In terms of testing, based on the August 2nd data, the US has about 52,942,145 people tested out of a population of over 332 million, which works out to 1 out every 6 people.
Even though this testing rate is quite high, most often the results take days to come or are unavailable altogether.
This means that, by the time the test results are ready, the infected person has already gone about spreading the virus to others.
In addition to the absence of widespread testing to identify which individuals need to be isolated, only some US states have mandated a lockdown, and even when it’s been applied, there has been minimal enforcement.
So in sum, without a federal mandate or enforcement of a lock down, it’s been largely a scattered state-by-state effort that has largely been voluntary.
In terms of raising the line, healthcare workers have generally had inadequate PPE - especially N95s - to feel safe, and as a result hundreds of physicians and nurses have gotten ill or been quarantined.
Meanwhile, intensive care units, or ICU, beds have started to run out, ventilators are in short supply, and there have been runs on medications like hydroxychloroquine.
Unfortunately, in the context of having scarce healthcare resources, we know that mortality rates can be quite high.
Now here’s the good news.
A complete lockdown, meaning one that’s enforced rather than voluntary so that the maximum number of people abide by it, can stop the spread of COVID-19 within a matter of days, even in a country that is seeing exponential growth like the US.
To show how this works, let’s start with a community that’s already seeing an exponential growth in COVID-19 cases.
Most folks with COVID-19 have mild symptoms, or have just gotten it and haven’t even begun showing symptoms yet.
There are two options at this point.
Option 1 is to let things continue with a voluntary social distancing policy where some adhere to it, while others continue to throw pool parties, keep businesses open, and invite relatives over for dinner.
In that scenario, even with the best of intentions and cleaning precautions, over the next 2 weeks there’s still going to be an exponential growth in cases, causing hospitals to fill up with patients, and many people will die.
But now consider option 2.
In option 2, there’s an enforced lockdown with absolutely everyone confined to their home.
If that were to happen, the virus could spread to household contacts, but after that, the transmission would abruptly end.
As these infected people recover, with no access to new hosts, the virus basically has no place to go and within 2 weeks the number of new cases starts to fall.
Fewer cases means that the healthcare system doesn’t get overwhelmed and the mortality rates fall because everyone who needs care can get it.
This approach and timeline is based on real data from Hubei where they implemented option 2.
The rate of new cases decreased within a few days of the lock down, and because there’s a lag between people getting sick and going to the doctor, that decrease was seen about two weeks later in terms of fewer new cases coming to the hospital.
The Bottom line is voluntary social distancing is only as effective as the number of people who are practicing it.
If enough people don’t adhere, then the virus can continue to spread, and the pandemic drags out, ultimately resulting in more deaths.
Now, as of August 1st, for a variety of reasons, especially economic ones, many countries around the world as well as many US states had to ease some of the restrictions enforced.
However, when social distancing measures are relaxed too quickly, there’s a higher risk of experiencing a second, even larger wave of infected individuals.
This is exactly what we encountered in 1918 with the influenza pandemic, commonly known as “Spanish flu pandemic”.
That pandemic was caused by a strain of the H1N1 influenza virus and infected about 500 million people worldwide, and killed 50 million people.
Now, the spanish flu pandemic occurred in three waves, the first wave was in March of 1918, the second wave was in the autumn of 1918, and the third wave was in the winter and spring of 1919.
In fact, the second wave was more deadly than the initial one, presumably due to the fact that it was spreading on crowded trains, and in field hospitals and camps during World War I.
In fact, even though the third wave was less deadly than the second one, it was still more severe than the original.
Now, it’s also important to remember that in 1918, healthcare workers were limited, and viral diagnostic tests, vaccines, antiviral drugs, and antibiotics were basically nonexistent.
And although some cities enforced measures such as shutting down schools and prohibiting public gatherings, it wasn’t a widespread national effort
Bottom line, for COVID-19 we have more tools available, but the lessons are clear for what happens when we start to congregate in groups.
The chance for outbreaks and an overall surge goes back up, and if the virus does spike again in fall or winter, during or near the peak of the seasonal flu season, the consequences could be even more devastating.
Looking at the current pandemic, over the last month, some countries like Australia and Japan started lifting restrictions, and have already seen a surge in the number of cases.
The surge can largely be attributed to some people disregarding social distancing norms and gathering in pubs and restaurants.
On the other hand, countries like New Zealand that managed to contain the first wave, have not seen case surges after relaxing the restrictions.
Now, in terms of mortality, the data shows that COVID-19 mortality rates differ by group.
So for example, if you split things out by age you can see from this table the fatality rate is relatively low if you’re below 60, with few deaths seen in children 9 and younger, but then starts to really climb up for the elderly, so they’re really the ones at highest risk.
And of course the elderly are more likely to have a lot of these conditions so it’s not surprising that they go hand-in-hand.