Headlines about countries like Iceland and Isreal seeing large rises in COVID-19 cases despite having a large percentage of their population vaccinated sound concerning. Headlines usually say things like, “60% of cases were vaccinated.” That sounds pretty scary. Some headlines have even offered doomsday predictions. If you look closer at the numbers, I think these countries are proof that the vaccines are doing what they’re designed to do. They’re not perfect, but they are performing pretty well.
It may seem that having cases in the vaccinated is a bad thing. It’s not necessarily. Vaccines are designed to prevent disease, not cases or infections. We don’t really care so much if you’re infected with a virus. We want to make sure you don’t get sick from it. Most vaccines, not just these SAR-CoV-2 vaccines, don’t provide sterilizing immunity. That means you can still be infected. There’s strong evidence that being vaccinated does lessen your chance of being infected, even by the delta variant. It just doesn’t prevent it entirely.
If it lessens your chances of getting infected, why do the vaccinated make up such a high percentage of cases in Isreal and Iceland? It’s a numbers thing. If most of your vulnerable population is vaccinated, as in Iceland and Isreal, most of your cases are going to be in vaccinated people. There are fewer unvaccinated people to infect. If you expose a group of 100 people and 85 are vaccinated, you may even have more cases in the vaccinated than the unvaccinated. You’ll just have fewer cases overall. That math is hard to wrap your head around. Here’s a simplified visual representation where each group has 2 infections, so it’s 50/50. The two cases in the vaccinated 85 mean a 2% infection rate. The two cases in the unvaccinated 15 mean a 13% infection rate. If the overall rate of infection was the same as the unvaccinated group, there would be 13 people infected. Since part of our population was vaccinated, we’ve reduced infections by 9 people. The headline would still say, “Fifty Percent of Cases Were Vaccinated.”
The most important thing to remember is that the hospitalization and death rates in Iceland and Isreal are pretty low, despite the number of cases. Their absolute case count is also pretty low. Delta has caused a bit of a spike (no pun intended) because the vaccines aren’t as protective against Delta as they were against Alpha, but they still offer really good protection against hospitalization and death.
Here are some graphs to prove this. These graphs are standardized to cases per million people. That makes a difference in how we visually interpret them. I’ll have the raw data graphs after the standardized ones. These are from Our World in Data.
Here are the actual counts, because I think the relative counts lead to overestimation of risk when we just look at them. The fact is, even a “risky” day in Iceland is 0 deaths and 3 hospitalizations.
These vaccines are actually doing their job, even against the Delta variant.