95% Effective

Let’s put it out there: this is a very high stress time. Most days, I feel like the only time I’m actually relaxed is the ten minutes after I finish running in the morning. The next week is not likely to bring very much relief. Regardless of what you are doing for the holiday you’re probably feeling anxious about it, or sad, or both.

But there is some good news to cling on to. One thing I will highlight: the vaccine news is great. A 95% effective vaccine is really more than we could have hoped for. This is a light at the end of a tunnel, even if not an immediate one.

Side note: someone asked me to explain what 95% effective means. Here we go, briefly. In these trials they take a big sample of people (30,000 to 40,000) and randomly assign them to get a vaccine or a placebo shot. They then observe their chance of being infected. The placebo arm of the trial — the non-vaccine group — gives you a sense of the number of expected infections without the vaccine. By looking at the difference between the number infected in the vaccine group and the number you’d expect in the placebo group, you figure out the efficacy.

For example: if you see 100 infections in the placebo group, and 5 in the vaccine group, that tells you that 95 of the infections that you would have expected based on the placebo group rate were blocked by the vaccine. So that’s a 95% effective vaccine.

It is true, I will note, that some people who are vaccinated did get the virus (although notable in the case of the second vaccine, the Moderna one, there were no serious cases in the vaccinated group, suggesting the vaccine did provide some protection even in people who got the virus). But this is always true, and 95% is a very high protection rate. Flu vaccines are rarely above 60%. Measles vaccines — a gold standard — are 93 to 97% effective.

Overall: really, really positive news. We just need to keep people safe until we can actually roll this out.