COVID-19 At A Glance

March 22, 2020 1 Comment

(A quick note: I know I’ve been gone a long time. I have a post about where I’ve been as well as a post about climate change in the pipeline so stay tuned. I put this together and out first because of the urgency of the situation.)

COVID-19

Those of you close to me will know that for the past week or so I’ve been sick. Due to the nature of my job at an Autism therapy clinic for children, I come into contact with a lot of germs and unsavory substances. Last week I stayed home from work (my workplace is now closed) and on one day was so fatigued that I was only awake for about three hours total and in my waking hours was unable to walk across my home without needing to sit down. I was all but certain I’d gotten the virus. While sick I also developed pink eye and decided that was the time to go see the doctor.

I was like this, but me.

Because my symptoms were COVID-esque, when I arrived at my doctor’s office the receptionist had to call the back of the office to report that I had arrived, gave me a mask to wear, and instructed me to stand, not sit near storage in the waiting area until I was called back. It was a surreal experience, but completely necessary that they would take such precautions.

Turns out that I probably don’t have the virus but had what was called an adenovirus that developed into a sinus infection which began to mess with my tear ducts and eyes. Three days later of taking an antibiotic and now I’m feeling fine save for a cough.

A Little History

Severe Acute Respiratory Syndrome-Related Coronavirus 2 (SARS-nCoV-2) is a virus which causes the disease known as COVID-19. The disease is characterized most commonly by a dry cough, fever, and shortness of breath which will appear 2-14 days after exposure.

 According to worldometers.info, there are now more than 300,000 cases worldwide. The World Health Organization’s (WHO) COVID-19 Situation Report from March 19th lists that the first 100,000 cases took more than three months to emerge, the second 100,000 took only twelve days, and using numbers from worldometers.info we can see that the third 100,000 cases took only four days. We’ll discuss the rate of the spread in more detail later on.

As detailed in the article from Rothan and Byrareddy (2020), the first cases of disease due to the virus were reported in late December of 2019 and thought to have originated at a wet animal market in Wuhan, China. From December 18th to 29th, five people were hospitalized and one of them died. As of January 30th, there were 7,734 confirmed cases in China and 90 in other countries across the world with a 2.2% fatality rate. At the time of writing this on March 21st, according to worldometers.info there are now 303,753 confirmed cases worldwide with 12,965 deaths, a roughly 4.3% fatality rate.

Pan(dem)ic

Less so now, but a week or two ago, many people may have seen the precautions the staff at my doctor’s office took as extreme or paranoid. People survey the world and form conclusions about it in largely intuitive terms. It’s mentally exhausting to constantly challenge your assumptions and biases, so we take shortcuts. The issue with this component of human nature is that it leads to overlooking things which aren’t readily evident.

In the case of COVID-19, you may see these social distancing and other cautionary steps as paranoia because no one you know has the virus. The virus’ presence in your town won’t be obvious to you until it is too late. This is part of why viruses are so effective and how pandemics can do so much damage. Viruses which we don’t have vaccines to protect against grow pseudo-exponentially. What is meant by this is that for a time, the spread of infections in a population will grow by a magnitude stronger each day than the last.

A Math Lesson

Joe from “It’s Okay To Be Smart” had a great video and analogy for explaining this principle. In this analogy we imagine a pond to be covered in lily pads starting with one pad. If each lily pad produces one new lily pad each day and be fully covered in 60 days, how long will it take for the pond to progress from 50% coverage to 100% coverage? The answer is ONE DAY: on day 59, the pond will be 50% covered, then the next, by each lily pad producing one new lily pad, that half will become full. Another useful heuristic he details in this is that the pond will not reach even 10% coverage until day 54.

While the exponential growth factor of COVID-19 is not quite 2 as it is in the lily pad analogy but closer to 1.1-1.4, the growth still occurs extremely fast. The YouTube channel “3Blue1Brown” has a video detailing how exponential growth works in reference to COVID-19 and provides a simplified formula for calculating it. Using this formula, I calculated the worldwide and US cases we could expect to see in the next two months.

Using the worldwide confirmed case numbers provided by worldometers.info from March 19th (244,894) to March 20th (271,598) to get a growth factor (1.11), I calculated that in 60 days, the number of cases could be 142,332,898. That’s not a giant portion of the world population, but keep in mind that exponential growth means that the number of new cases daily will grow more quickly each day, and the growth factor I used was on the lower end.

Using that same growth factor with the number of US  confirmed cases for March 21st (22,738) also provided by worldometers.info, I found that in 60 days, the number of cases could reach 11,916,013, roughly 3.5% of the US population (using the higher US-specific growth factor of 1.17 calculated by case numbers from March 20th to March 21st instead, this number becomes 280,481,335, about 86% of the US population).

As I stated above, viruses grow pseudo-exponentially, not exponentially. Their growth rate will slow and eventually level off. To understand this, suppose an infected person has some chance of passing the virus off to someone they come in contact with. As a higher proportion of the population becomes infected, the likelihood of an infected person coming into contact with someone who is uninfected goes down because the pool of uninfected people is smaller, slowing the rate of growth.

Put in other words, if the majority of people are infected, you have a smaller chance of running into someone uninfected, and thus the the virus can’t spread to as many new people each day. Keeping this in mind, however, a great deal of the population would need to be infected first for this slowing to take place.

Optimism Amidst Chaos

Now seems like a good point to say that this post is not intended to scare anyone, but rather impart the gravity of the situation the world finds itself in. The information I’ve found is only any good to us insofar as it causes us to be safe, considerate, and take the steps necessary to slow this down. The danger of COVID-19 is not cause for anxiety beyond what is constructive. Torturing yourself with thoughts of how the world may end or panic-buying too many groceries exacerbates the current problem at best and causes new problems at worst.

As a small aside for hope, I was recently at the local grocery store. Most people moved about with purpose and grave expressions. The produce section was barren, the only canned goods in stock were some varieties of beans, the milk cabinets had signs about limitations on how many a single customer could buy posted, and the toilet paper section was as you’d expect at this point. It was genuinely like something out of a movie. I had been cooped up inside for quite a while due to being sick and emerging to see the world in this state was genuinely unnerving.

Stock photos are a special art form

It was the first time I had any palpable impression about how crazy this situation could get. But as I was leaving, I looked to the self-checkout and saw a little girl on her dad’s shoulders making faces in the monitoring camera and giggling. It was a cliché moment for sure, but one that made me realize that adopting a cynical and pessimistic attitude in this time is how the situation of the virus “wins” against me so-to-speak.

Hidden Danger

With that out of the way, it’s important to mention another factor that makes COVID-19’s spread so quick. A research letter by Bai et al. (2020) documented how a person can be a carrier of the virus without showing any symptoms. In this letter, they document the case of a 20-year-old woman (patient 1) who visited Wuhan, China (the suspected origin of the virus) in the very early days of infection and returned to her family elsewhere in China.

Five of her relatives (all age 42 or older) that she came in contact with demonstrated symptoms and tested positive for the virus despite not having visited Wuhan. Over the nearly month-long course of this case study, patient 1 remained symptom free while at different points testing positive and negative for the virus. The fact that in certain individuals, perhaps due to health or age, the virus can be carried but asymptomatic is why people should self-isolate even if they aren’t feeling sick themselves.

A sentiment which is, I think, being phased out to some degree is that because the disease caused by the virus is only life-threatening to elderly people and people with underlying conditions, that young, healthy people can freely socialize and need not worry about infection. The obvious issue here is that the concern is that you may become infected and pass the virus on to someone who is vulnerable.

What We Don’t Know

A further convoluting factor in detecting how serious the situation actually is, specifically in the US, is that the US has lagged behind in numbers of tests being run since the early days. According to an article from The New Yorker, soon after the virus was detected in the US, the CDC sent out test kits to around 50 public state and local labs. Before use, these labs have to run verification tests using the kits to make sure they operate as they’re supposed to. Apparently, 36 of these labs got inconclusive verification results, five had problems with reagents of the kits, and only six to eight could successfully verify.

Not to worry, though, private labs can also publish their own tests, right? Well it turns out that during public health emergencies, private labs need to receive Emergency Use Authorization (EUA) from the Food and Drug Administration (FDA). The FDA has since altered this protocol, but even as late as early February, labs wanting to secure EUA for their test had to physically mail an application to get authorization then wait for a response. While it is important that labs’ tests in a public health emergency are top quality, the requirement to apply via mail delays labs from testing and also puts a brake on their production of tests pending approval.

In a paper by Lachmann (2020) seeking to correct the underreporting of cases, the researcher comments that as of March 14, South Korea which has the highest COVID-19 testing numbers in the world was able to test 20,000 people per day compared to the US’ roughly 4,000 at the same time according to covidtracking.com. While the US has since raised these numbers significantly and is now testing around 34,000 people per day (March 19th to 20th), and these numbers will raise rapidly over the next few days as back-logged test results come in, our initial delay in test kit availability is a major setback to detecting the saturation of the virus in many locations.

In that same paper by Lachmann, the researcher estimates the extent of underreporting of cases by considering a series of variables from WHO case, death, and recovery numbers, country populations, and demographic vulnerability all in reference to the “benchmark” testing country, South Korea. With all of this in mind, Lachmann estimated that the US, which at the time of writing had 2,179 confirmed cases, would actually have closer to 6,085 cases. If Lachmann’s estimation is close, this would mean that at the time 64% of cases were unreported.

I’m not going to speculate about the current situation and what percentage of cases are unreported, but it’s worth noting that though the number of tests run daily is higher, so too is the number of infected people.

Where to from here?

A story from the 1918 influenza pandemic illustrates a very important point about precautionary measures to curb a virus from spreading. As discussed by Hatchett el al. (2007) in their paper about the 1918 influenza outbreak, two cities, Philadelphia and St. Louis had very different responses to detection of the disease in their city.

 Upon learning of the disease, Philadelphia officials dismissed the severity of the situation and still allowed public gatherings, notably a parade which had been scheduled. St. Louis on the other hand responded in two days by closing schools, churches, and playgrounds as well as banning gatherings of more than 20 people. The results of these differing efforts is detailed in the graph below from Hatchett et al.’s paper. Philadelphia at one point had a weekly death rate of 257 people per 100,000 while St. Louis’ peak, with precautions in place, was only 31 people per 100,000.

Credit: Proceedings of the National Academy of Sciences

What to do about it?

By now I’m sure you’ve heard what you can do to help. Wash your hands frequently, don’t leave home unless you have to, keep your distance from others as much as possible, don’t touch your face, cover your coughs using sleeves and tissues, etc., etc. It feels like the world is sort of burning down out there, but by staying in as much as possible, you’re doing the entire world a favor. A collective effort is the only way to slow the spread. There are treatments being explored like immunoglobulin therapy, hydroxychloroquine, Remdesivir, and others; but these all take time to investigate their efficacy for treatment and approve.

Even if a proper treatment emerges, it is better for the virus to just be stopped from spreading at all. As shown by the orange curve in the graphic below, when precautionary measures aren’t taken, people get sick all at once, overwhelm the healthcare system’s capacity, and then more people die. When measures are taken, as shown in blue, people get sick more progressively rather than all at once, the healthcare system can treat people, and fewer or no people have to go without treatment. This is what’s being talked about when people say “flatten the curve”.

Be sure to thank anyone you know working in healthcare, police, and grocery workers because it’s certainly a scary time for them right now and they’re all vital to keeping our society going, now more than ever. As another note, make sure to reach out and keep in contact with people you care about, particularly those living alone or with mental health issues. Quarantine is rough on everyone, but isolation can be particularly destructive when you’re struggling with other things already.

Keep in touch (not physical), wash your hands, and thanks for reading.

Here’s an additional excellent video for you if you’re interested.

References

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