Electron micrograph of Coronavirus replication in a cell.
We have now begun the process of “social distancing” or shutting down certain activities across the country to prevent further spread of the Coronavirus that causes COVID-19. In order to follow the recommendations it’s important to understand why we taking such drastic measures to control something that has so far only affected just a few people in the country. The key is understanding what exponential spread means and how social distancing works to save lives.
America and most of Europe is like Italy, we’re just 1-2 weeks behind.
I’ve been looking at data like this for weeks but was reluctant to post it publicly for two reasons. First, I wasn’t sure if it was going to be correct and I only want to supply accurate information. Second, I didn’t want to be accused of causing panic. At this point, as we see school and non-essential business closures all over the country and all over the world, I think it’s important to understand why we need to do it. Most of you have already heard about “flattening the curve” to avoid overwhelming our hospitals with critically ill patients all at once and I think this graph brings that message home in a way I haven’t seen elsewhere. Italy started shutting down parts of the country two weeks ago in an attempt to do just that and they were late. We (and most of Europe) are about two weeks behind Italy and progressing rapidly to the same endpoint.
Unchecked, the virus that causes COVID-19 spreads rapidly through populations. The average person will spread it to 2-3 people but some have spread it to many more than that. You are contagious before you show symptoms and the incubation period is up to 14 days. The pandemic has progressed in multiple countries at almost exactly the same rate until they hit the point of public awareness but by then it was too late. The cases appear to double every 3 or 4 days if nothing is done to slow transmission. That is what is known as “exponential spread”.
For a good example of exponential spread, try this simple experiment. On a calculator, enter 2 x 2 and hit “=”. Then hit “=” again. Keep hitting “=” another 17 times. It starts out slow but gets above 1 million very quickly. That’s what 80 days of doubling every 4 days would do.
The graph below shows how the virus is progressing in a number of countries including America, and demonstrates that we are not exempt from the laws of epidemiology. In fact, due to the lack of testing, we may be worse off than the data show. If the data is correct, we are about two weeks behind Italy which means we will begin to see large volumes of cases at our country’s hospitals and ERs in the next week or two. It will vary by the area of the country and may be delayed in some places but it will happen if nothing is done. It looks like it’s already happening in NYC and Seattle, WA.
[This chart was made with publicly available confirmed cases and population data and are expressed as cases per 100,000 people to level the playing field between small and large countries. It was made by a reddit user in this post who continues to post updates.]
Okay, We’re Social Distancing, Now what?
So let’s say that we manage to achieve “social distancing” effectively for two weeks, haven’t run out of toilet paper, and the kids haven’t killed each other yet. What will we see? Not much, unfortunately. The news may continue to get worse despite our best efforts and here’s why:
Social distancing and shutdowns, like we’re starting now (March 16th), work with a delay. The person who is critically ill today was exposed at least 2-3 weeks ago. The people who were infected last week won’t be getting their first symptoms until this week or next. After that, in those who progress to more serious disease, it takes another week before they show up in ERs with shortness of breath or other serious symptoms.
Italy is still seeing significant increases in infections and deaths despite shutting everything down a week ago (March 9th), for the same reason. Watch closely what happens there. Italy’s cases should start to slow down in the next week or so. It’s going to seem like what we’re doing isn’t working either. Give it time. Stick with it. If we do it right, it will start to work. My guess is that they’re going to extend the social distancing policies for at least another few weeks but who knows? If we end them too early we may defeat the purpose. We want to slow the spread so that our health care system can handle those who get sick and not get overwhelmed by too many cases at once.
What If You Get Sick?
If you start to feel a little sick there’s no need to rush to the doctor or the hospital but please don’t go to work or public spaces and expose other people. It’s still most likely a regular cold/flu or even allergies. For most of us who get it, COVID-19 will be a mild illness that we can take care of at home. According to the very comprehensive Report of the WHO-China Joint Mission on Coronavirus Disease 2019 (COVID-19) typical signs and symptoms of COVID-19 include:
Fever (87.9%), dry cough (67.7%), fatigue (38.1%), sputum production (33.4%), shortness of breath (18.6%), sore throat (13.9%), headache (13.6%), myalgia or arthralgia (14.8%), chills (11.4%), nausea or vomiting (5.0%), nasal congestion (4.8%), diarrhea (3.7%), and hemoptysis (0.9%), and conjunctival congestion (0.8%).
People with COVID-19 generally develop signs and symptoms, including mild respiratory symptoms and fever, on an average of 5-6 days after infection (mean incubation period 5-6 days, range 1-14 days).
Notice that nasal congestion is relatively rare. Hemoptysis means coughing up blood and “conjunctival congestion” is “pink eye”. From what I’ve heard the fatigue is very severe.
If you think you have COVID-19, call your doctor. They are starting to roll out testing in southeast PA and you may even be able to do drive-up testing. If you do have it, your doctor will tell you what to do, and it might involve testing the rest of your family and people you’ve been in close contact with recently. If you’re negative, just stay hydrated, rest and wait until your symptoms get better.
In the small percentage of people who progress to more severe disease, it usually develops over about a week after you initially have symptoms. In that case you may feel shortness of breath or difficulty breathing. That’s the point when you should call your doctor, call 911, or go to the emergency room. If you do decide to go to the ER, it’s best to let them know in advance so they can be prepared with the appropriate protective equipment.
What About Children?
Everyone wants to know about Coronavirus and children. The WHO report I previously referenced has only this one paragraph about children:
Data on individuals aged 18 years old and under suggest that there is a relatively low attack rate in this age group (2.4% of all reported cases). Within Wuhan, among testing of ILI samples, no children were positive in November and December of 2019 and in the first two weeks of January 2020. From available data, and in the absence of results from serologic studies, it is not possible to determine the extent of infection among children, what role children play in transmission, whether children are less susceptible or if they present differently clinically (i.e. generally milder presentations). The Joint Mission learned that infected children have largely been identified through contact tracing in households of adults. Of note, people interviewed by the Joint Mission Team could not recall episodes in which transmission occurred from a child to an adult.
The bottom line is very few children were infected and even less got very sick. There was only one reported fatality among the 965 children who tested positive in the WHO data. It’s still an open question if children can pass the infection to adults even if they don’t get sick themselves, so out of an abundance of caution we are closing the schools and using the same social distancing measures with children as we do with adults.
Is There Any Hope?
I know it all sounds so grim but this epidemic will end and the vast majority of us will get through it in good shape. Many people have wondered if the warmer weather will slow the spread of the virus. So far, we have not seen that happen. The virus is spreading in Australia which is currently in their summer season.
Fortunately, this virus, like other Coronaviruses, appears to confer immunity to future infections and it is extremely unlikely that any of us will get it again, despite a few exceptions you may have read about. The virus that causes COVID-19 is not related to the flu and is very unlikely to “mutate” to a new virus. If you read my previous post, you would know that the flu has an 8-segmented genome and it can recombine with another flu strain to create brand new ones, which it does every year. This virus has a single genome and won’t be able to do that.
Once enough of us have had COVID-19, which could take a couple of months, (or a vaccine becomes available in 12-18 months), our society will develop “herd immunity”. Herd immunity, where enough people are immune to the virus among the population, essentially stops the virus from spreading, although it may pop up in certain areas from time to time.
So stay safe, wash your hands, don’t touch your face, and practice your social distancing the best you can. Also do your best to help those who are adversely affected by the shutdown such as service employees and small businesses. Ask your political representatives to focus government aid on working class folks who can’t “work from home” and who will really need the help. We will get through this!