COVID-19 Vaccine Efficacy Explained - It's Not What You Think

What does the Covid-19 Vaccine Efficacy actually mean? It's not what you think. Unless you’ve been living under a rock these past two weeks, you probably heard the great news that two of the leading vaccine contenders for Covid-19 have had some amazing initial results. The joint effort by BioNTech and Pfizer announced on November 9th that their vaccine candidate has a greater than 90% efficacy and just this week on Nov 16th Moderna announced that their vaccine candidate has a 94.5% efficacy. I’m not an expert on vaccines, but based on everything I’ve been reading, this seems like an absolutely major success that we should all be celebrating.

And it’s because I’m not an expert on vaccines that I’m not going to discuss the differences between these two vaccines or how they’ll be distributed or even how likely they are to have side effects. There are a bunch of amazing YouTubers putting out really great content on just this. Instead, since my expertise is in data, I’m going to help you understand what those efficacy numbers actually mean. And I’ll fully admit that when I first read the news stories about these vaccine candidates, I did not interpret those values correctly at all...and I’m guessing neither did you.

Welcome to Data Demystified, I’m Jeff Galak and if you stick around, I’m going to debunk what I think is the most common incorrect interpretation of those efficacy numbers and then explain to you what they actually mean.