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Day 13: Mortality Rate

Today I remembered a conversation I had a couple of months ago. It must have been past mid-January, because I had just returned from Milan. I was at the skating rink talking to another mom. Sitting next to us, the father of another skater, who happens to be a medical doctor, worked on his computer. I don't remember the exact details of the conversation, but I found myself saying that I wasn't particularly worried about the virus since its mortality rate appeared to be double the one of the flu. The doctor almost fell of his chair, as I spoke.

"I am," he said. "Humans don't have immunity against coronaviruses."

He proceeded to explain, something I didn't fully understand then, that the hospitals were at full capacity as it was, and that they would be overwhelmed if a large part of the population got sick.

Being a medievalist, my main experience with pandemics comes from reading about the Black Death. The plague was caused by a bacterium, Yersinia Pestis, which was found in fleas, carried by rats. Y. Pestis causes bubonic, pneumonic, and septicemic plague. Without treatment, bubonic plague has a mortality rate of between 40 and 60%. Pneumonic plague has, depending on who you ask, a mortality rate somewhere above 95%. Septicemic plague is almost always fatal. Of course, we can now treat these infections with antibiotics, but there were no antibiotics in the Middle Ages. The only thing that could help you was to have the Delta 32 mutation, which deletes part of the CCR5 gene. In theory, if you have one set of Delta 32 you could get the pest and recover; two sets and you should have been immune (homozygous carriers of the Delta 32 mutation are also immune to HIV-1. See Eric de Silva, Michael P.H. Stumpf, HIV and the CCR5-Δ32 resistance allele,FEMS Microbiology Letters, Volume 241, Issue 1, December 2004, Pages 1–12, I guess that most medievalists are unfamiliar with Delta 32 and CCR5. For me, it's always a good conversation piece with a certain flavour of biologist.

All this is to say that, by training, I have studied a pandemic with a much higher mortality rate than SARS-CoV-2. Probably for this reason, a number under 15% didn't make the impact that should have. When I first thought about a 1 to 3% mortality rate, it seemed something unlikely to affect me personally (although, of course, it could). I couldn't see then that is not about our odds as individuals but about vulnerable people who should not be dying but are.

In January, it was not conceivable that two months later the government would ask us to stay at home and keep distance from each other. We need to do it to protect the vulnerable, in the same way that vaccinations also protect those who cannot have them by keeping the diseases out of the community.

That a pandemic was coming was something epidemiologists have know for a long time but people with Ph.D.s in literature had just read about in Science Fiction books.

I would have liked to be a biologist.

10:27 pm:

Canada cases 5,655

Deaths 61

Recoveries 466

World cases 664,695

World deaths 30,847

World recoveries 140,156


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