Virus can bash you even if you think your guard is up

My brother in Houston tested positive for Covid yesterday. I am writing today about how incredibly lucky we are. This may seem an odd statement, given that 316,000 of my fellow Americans are dead from this nasty disease and my brother has a very small but real chance of joining them.

My brother AJ is 50, and in good health otherwise. So far, he feels fine but, of course, that could change quickly. We think he was probably exposed last week at a small, masked outdoor gathering with a few neighbours. Two others in the group now have it too.

They took precautions — but not nearly enough. They wore masks, but not when they actually ate and drank. They distanced, but obviously not far enough. They were outside, but that’s not a magic bullet either.

In Texas, where the right-wing Republican governor has been pushing President Donald Trump’s Covid denial and anti-masking madness, AJ is actually regarded as a Covid fanatic who avoids most risky situations. That’s in part because various family bubble members are elderly or immunocompromised. Now everyone is in serious quarantine to make sure it doesn’t spread further. So this is going to be a very, very anxious Christmas for the Brass family.

And yet, it could have been so much worse. The case fatality rate (CFR) for Covid varies by country and situation, but it’s thought to be about 1.7 per cent for all cases averaged together in the United States right now. It’s probably less than 1 per cent for AJ. It rises dramatically to 10 per cent and higher for the high-risk elderly. But Covid’s close cousin Sars killed about 10 per cent of everyone infected. Mers, another coronavirus, kills about a third. The CFR for smallpox is similar. Untreated plague kills about two thirds. Ebola kills up to 90 per cent of its victims in some outbreaks. Rabies kills almost 100 per cent of all untreated infections. As did early untreated Aids.

The fact that Covid is a disease on the low end of potential lethality was not a given. There is nothing special about Covid that required it to be as it is. It could have been as deadly as smallpox or even rabies. While it’s true that successful diseases tend to gradually become less lethal so they can spread more widely without killing off their hosts, there is nothing in biological science that sets the human lethality of a new virus. It is