Corona Virus information from my Wife

From Meghan Work Boedges :

My friend Jodi R. R. Smith asked me to write something, as an Epidemiologist--it's long, hope you don't mind:

First off, although I found infectious disease and particularly zoonotic diseases fascinating during my master’s program (in Public Health), for various reasons mostly related to what fellowships were available, I focused on cancer, during my PhD, and I still do. So I am definitely not an infectious disease expert. There are several good articles and tips from infectious disease experts floating about—epidemiologists and physicians, and I defer to what they say about infection spread, prevention, etc. I know more than SOME people. Like our President. I know more than him.

One thing that has bothered me in the coverage of this disease is the conflation of two different measures of death from disease—case fatality rate, and mortality rate. These are different things. The mortality rate (MR) is the proportion of people who have died of disease, of all those who are at risk of getting the disease, and it requires some specification of time (1-year mortality, 5-year mortality, etc). The denominator of that equation, “those who are at risk”, can be as broad as “everyone in an entire population”. For lung cancer, anyone who has lungs is, theoretically, at risk of getting lung cancer. Right now, everyone in our population is theoretically at risk of getting COVID-19. So the denominator for mortality, is very large, and the numerator is, right now, small.

Case fatality rate (CFR) is defined as the number of people who have died of disease, out of all those who HAVE the disease. In cases of infectious disease outbreak, the time period for case fatality is usually, implicitly, short. If you don’t die of COVID-19 within weeks of experiencing symptoms, you are not going to die of it. Ebola is an example of a disease with a high case fatality rate, and a low mortality rate. The average CFR of Ebola is about 50%, but can be as high as 90%. But it is a rare disease, so has a low mortality rate. What’s more, the HIGH case fatality rate actually helps keep the disease rare—it kills people who are infected, so quickly and so often, it basically blows itself out—it doesn’t keep enough people, alive long enough, for them to transmit it to enough other people. Seasonal influenza is an infectious disease with a low CFR, but with a high mortality rate—because it is common. Its low CFR keeps it common. Only about 0.1% of people who get it, die from it, but in the meantime plenty of us get it, and pass it on to others. This also speaks to how infectious (contagious) it is.

I have seen some people use mortality rate to indicate that COVID-19 is not any worse than the flu, because many more people have died of the flu this year. And certainly, we don’t take these kind of measures—mass quarantine, social distancing—to protect against flu (we also have vaccines for the flu, though!) But that is an inappropriate comparison, because the COVID-19 CFR, while certainly lower than Ebola, is certainly HIGHER than the flu, and because none of us have an immunity/are vaccinated against it, we are ALL at risk. The coronavirus that causes COVID-19 also seems to be quite contagious. It appears to have what’s called a basic reproduction rate (R0) higher than 2, which means on average, each infected person, passes it one to more than 2 other people. Any R0 higher than 1 means an infection is likely to keep spreading.

Now the problem we are all facing in the US, is that we don’t really know what the CFR is, because of incomplete testing. The denominator, “those who have the disease/had the disease” is under-measured. I think the country that has the most complete testing, done in the timeliest manner, and with enough positive cases that the data is robust, is South Korea, so I’m going to use their CFR, as a measure of what the “real” CFR likely is (keeping in mind, the CFR can also differ depending on the makeup of the population in terms of age/other health issues, and also based on health care resources in the country). In S. Korea, as of this writing, there are 8,162 cases and 75 deaths. That’s a CFR around 0.9%, or nine times deadlier than flu. If you look at Italy, by the way, the CFR is 1,441 deaths out of 21,157 cases, for a CFR of 6.8% (!). For the US, there are currently 62 deaths out of 3,110 cases, so about 2%. (Source: https://www.worldometers.info/coronavirus/). I can’t verify that source, but you can use official WHO “situation reports”—last updated early Saturday morning 3/14, so it’s already out of date, but I can vouch for accuracy: https://www.who.int/…/novel-coronavirus-2…/situation-reports.

OK, so now we’ve established that COVID-19 has a CFR of ~1%, 9-10x deadlier than the flu. It appears to be just as infectious, and worse, it seems to have a longish “incubation period”. That’s the time from when you are infected, to onset of clinical illness. For flu the incubation period is a couple of days, so you don’t have as much time to pass it along to others. For COVID-19 it is about 5-6 days, sometimes shorter, sometimes as long as 14 days. So, that sucks because people are walking around feeling fine and dandy for almost a week, passing it along as they go. Some people, particularly young people, may have symptoms so minor, they barely give it a passing thought.

More data shows that that the CFR of COVID-19 is quite different by age. This is often true of infectious disease, but it seems particularly tilted here. Both South Korea and China have age-specific info, but I’m going with China for this data simply because South Korea had so few cases die, they have too small a sample to evaluate deaths by age. So here’s a chart of CFR, by age, in China (where the overall CFR was 2%, 2x as high as South Korea—probably as a result of some initial undertesting plus the fact that this was a new disease that nobody knew what to do with). https://www.buzzfeednews.com/…/coronavirus-death-rates-age-….

As you can see, we are not closing schools because children are at risk of dying. We are closing schools so our children don’t infect grandma and grandpa. I saw another post where someone showed similar data and then told people under 50 to “go live your life”. Um, unless your life involves never interacting with anyone who is over 50, or interacting with anyone who ever interacts with anyone over 50, that is terrible advice. MY advice is—if you are 60 or older, or you know someone 60 or older, parent, neighbor, etc, advise them to stay in their home as much as possible. Reach out to your older neighbors/relatives—by phone or text or e-mail, and see if you can help them. If they need something at the grocery store, offer to buy it for them and leave it by their door. Or help them with an online delivery. If they need prescriptions, see if the pharmacy can send it to them. That kind of stuff. If you and your kids are still going to work outside the home, or activities or school, do not go visit grandparents or have them visit you. Really. Same if you have a relative with an underlying medical condition, particularly one involving the heart or lungs. And to be honest since you don’t know who you will run into or what their physical health is, it’s best to limit your activities as much as you can. This is what altruism is about.

So basically we have a virus 9x deadlier than the flu, with a longer incubation period, that is highly contagious, which no one has immunity to. Is it serious? Yes. In a way it’s kind of the worst type of virus because it’s not virulent (aka severe or deadly) enough to that it doesn’t blow itself out, and just keeps infecting and infecting for a long time and so it may never really go away. But in the meantime people feel it’s overblown because it doesn’t kill that many people, because (for now) it’s still rare. After a long time, enough people will be infected that immunity may develop, and herd immunity could set in (or an effective vaccine will be developed). But it is just deadly enough that we don’t WANT to get so many people infected that herd immunity develops quickly—that results in too many deaths, and it would increase the CFR due to an overwhelmed health care system, for people who may otherwise have recovered.

How many people will ultimately die? I don’t know the answer to that. Will the US have a similar situation to a country like Italy? I mean in absolute deaths, yes, that could easily happen, but the US has a much larger population than Italy. What few people point out is that the US also has a much lower population density than Italy, and also a much lower median age, and this may actually spare the US somewhat. The population density in Italy is 532 people per sq mile. The population density in the US is about 92 per sq. mile. (China is 375 per sq mile, by the way). Like all infectious diseases, higher density areas are at higher risk of disease spread, we see this in the US already. The median age in the US is 38 years, the median age in Italy is 47 years. Most European and Asian countries are more densely populated than the US. Most European countries are older. As much as Iran screwed up in their own response to a COVID-19 epidemic in their country, they may be helped by a median population age of just 31 years. I haven’t seen this mentioned and I hope its being taken into consideration when estimating risk and fatality.

Is what everyone is doing--worth it? Well, many people have shared with me the “flattening of the curve” graphic, and this is what we are trying to do with the measures that are being implemented. Keep in mind that flattening means that the disease is spreading for a longer period of time, than if we just kind of let it run rampant—in order not to overwhelm our healthcare system. It’s the prudent thing to do, but it means this thing will be with us for awhile, sorry to say. Also, I found this source after I wrote most of this, and it is a good aggregate source that basically shares everything above and additional information, with simple graphics about common symptoms and updates by country:

https://ourworldindata.org/coronavirus.

Hope that helps!!

Also, keep in mind these actual benefits:

--Lower carbon emissions—fewer cars on the road and planes in the air

--Lower likelihood of a mass shooting. For real—schools, business, houses of worship closed, concerts canceled.

--China may hopefully get their act together on these wild animal markets, which have now been banned. Some of the animals in the markets are critically endangered. Leave them and their diseases alone! (This coronavirus seems to have originated in bats, and passed through an intermediate animal, possibly a snake or the (endangered) pangolin, to humans via a wild animal market).

--Hopefully, increased time for reflection, introspection, and communing with nature.