Tuesday, November 23, 2021

Last week I posted some "back of the envelope" math on COVID, and of course ended up being wrong. And it might be interesting to hear where I made that error, because it is of some general relevance.

Based on infection numbers among vaccinated and unvaccinated people in one region of Germany, I calculated a number of high likely a vaccine is to protect you from infection. While I still believe that a vaccine offers some protection on any given day against infection, it turns out that this might not be relevant at all if you think of the long term. Think of it: In the long term, what is your chance to get infected at least once during your lifetime by the common flu? Obviously that number is very close to 100%, because regardless of how low your infection risk is on any given day, there are a lot of days in a lifetime. If the flu virus is everywhere, aka it is "endemic", sooner or later you catch it, even if you are living in a less populated area and don't go out much.

With COVID, and the delta variant, it pretty much is the same now. COVID has become endemic. Whatever social distancing you do, you can't lock yourself into a bubble forever. So, sooner or later you *will* catch COVID, regardless of whether you are vaccinated or not. So the only relevant number for protection from the vaccine is the British study that unvaccinated people are 32 times more likely to die than vaccinated.

From the Economist's estimate of COVID's true death toll, we can estimate that the chance of an unvaccinated person to die from COVID is about 1 in 300. So the chance of a vaccinated person to die from COVID is about 1 in 10,000. In the USA that makes dying from COVID for an unvaccinated person as likely as dying from being shot, while dying from COVID for a vaccinated person is less likely than dying from sunstroke. Of course the lifetime chance of dying from COVID isn't very accurate, as we only have 2 years of data yet. The virus could still mutate to a more dangerous variant and increase the chance of death to be as likely as dying in a motor vehicle accident, 1 in 100. Or new treatments could reduce the likelihood of death.

Nothing of that changes my original message: Getting vaccinated increases your chance to survive COVID. The risk from the vaccine is significantly lower than the risk of not taking it. Big Bird is right, you should get vaccinated.