How bad is the coronavirus?

1. In order to answer this question, let's look at two factors: fatality rate and infection rate:

1. Fatality rate is how likely it is for someone to die from a particular disease. If untreated or unvaccinated: Rabies has a 99% fatality rate. Ebola has around a 80%-90% fatality rate. Smallpox has around a 67% fatality rate. Avian flu around a 60% fatality rate. SARS around a 10% fatality rate. The measles around a 2% fatality rate. The seasonal flu (influenza) around a 0.1% fatality rate (note it's not 1% but even less).

2. Infection rate is how many other people one person will likely infect if they have a disease. The measles has a relatively low fatality rate, but a high infection rate at nearly 15 persons, i.e., one person with the measles can infect almost 15 people. Ebola has a high fatality rate, but a lower infection rate at about 2 people. SARS' infection rate is around 4 people.

(These are rough estimates, but estimates suffice for the purposes of this post.)

2. So where does this novel coronavirus (nCoV) fit in? No one knows for sure. However, given the empirical data from around the world (predominantly China), nCoV seems to have a fatality rate lower than SARS but higher than the seasonal flu so somewhere between 0.1% and 10%. At the same time, nCoV seems to have an infection rate higher than the seasonal flu but lower than or equal to SARS so around 1-4 people. To be fair, there's considerable debate over nCoV's fatality and infection rates, but I believe I'm presenting the majority view of medical and health experts.

3. That said, keep in mind the empirical data is possibly (and quite plausibly) inaccurate and certainly incomplete. As I mentioned in an earlier post, Johns Hopkins has a map that more or less tracks the nCoV in real-time. The first death outside of China was just reported hours ago. It was in the Philippines.

4. I'll mention one last thing. A Harvard epidemiologist named Eric Feigl-Ding has made some remarks on Twitter which, if true, would be extremely alarming. I think he's right to point out certain concerns, but I also think he makes a bit too much about the R0 number. In any case, time will tell whether what he has said is justified.