2021-04-22 General


I’m hearing murmurings about “If I am vaccinated, why can’t I do [X]?!?!?!”

Because vaccination is not perfect, and it’s not the most important thing, case counts per capita are.

If the efficacy of one shot of a vaccine is 80%, it doesn’t mean that if you are exposed, you have an 80% chance of getting the virus, it means that if 10 unvaccinated people would have gotten COVID in some situation, then only 2 vaccinated people would.

Imagine a party with 51 unvaccinated people, where one is contagious and gets 10 people sick. If all 50 healthy people had been vaccinated, then 2 people would still get sick. And if they then go to another party (because hey, they’ve been vaccinated!), they might get another 2 people each sick. Ooops, we’ve got exponential growth again.

What is really important here is to get rid of that one sick person.

One way is by not inviting them to a party — which means not inviting anybody to the party, because you don’t know who it is. In other words, keep the restrictions.

The other way is to drive Rt, the reproductive number, below 1 and drive the case count to small enough that there are unlikely to be any sick people around (and then contact-trace the hell out of any exposures). This is what New Zealand did. It is much, much safer to be unvaccinated in New Zealand than it is to be vaccinated in India. That’s why I say that the case count per capita is more important than vaccination.

The good news is that they are related! If you vaccinate enough people, then the virus has a harder time spreading: it’s only going to infect 20% as many people who are vaccinated as if they were unvaccinated people. That means that the virus will eventually die out in that population.

Now, unless we have a perfect quarantine system, we will still get introductions, and even if we have 100% vaccination, there will still be some people who get sick. We are never going to get to a zero-COVID state as long as there are places in the world where COVID is common. And it will suck for the people who catch COVID then, just as it sucks for people who catch measles now. However, it won’t mean restrictions on vast swaths of activities like we have now.

Yet another two studies show that the vaccines (especially the mRNAs) are still effective against the variant in this case against the “New York” variant B.1.526.


Direct passenger flights from India have been cancelled. Cargo flights can still come. If someone takes an indirect flight, they have to get one PCR test in the country they last departed from. Harsh but necessary. 🙁


The majority of the virus introductions into Canada came from the US. Only about 1% came from China. Suck it, racists!