Have you seen something like this on social media recently?
"Delta's so bad! A friend of a friend got COVID even though he got the vaccine."
It turns out this tells us more about social networks than it does about vaccines.
How? It's a small world after all! #scicomm 🧵(1/n)
Lots to unpack here, so let’s start from the beginning.
This is a social network. It helps us keep track of how people are connected.
In this picture, circles represent people, and the lines between them indicate who knows who. (2/n)
This social network has 5 people: 2 groups of 3 friends, with 1 friend in common.
Real social networks look a lot like this (but are much bigger, obviously). There's just enough overlap that lots of people are "friends of friends," just 2 hops away! (3/n)
So, what does this have to do with our perception of who's getting COVID, and how well vaccines work?
Basically, because we tend to know a lot of the same people – and we make comparisons between people we know – we can come to conclusions that conflict with the data. (4/n)
Let's say you're part of this social network, with 5 fully vaccinated people (circles) in Boston and 5 unvaccinated people (squares) back home in some other part of the country.
In this picture, you're the circle with the arrow pointing at it. (5/n)
Ok, now the delta variant shows up and makes a bunch of people sick. ☹️
Let's indicate these positive COVID cases in red.
As is the case in real life, more unvaxxed people than fully vaxxed people got COVID! (6/n)
In this example, the vaccine is 75% effective.
We say this b/c there's a 25% "relative risk" (RR) that someone vaxxed gets COVID:
And even if you do get COVID after getting vaccinated, your symptoms will be milder, and your outcomes *way* better, than if you didn't get the shot. (13/n)
Back to social networks: all of this is closely related to "six degrees of separation," the idea that any two people on Earth are at most six social connections apart.
You and Kevin Bacon. You and a Fortune 500 CEO on LinkedIn. You and Queen Elizabeth II. (14/n)
All it takes is a few people with friends in unexpected places to connect the whole world!
So, it’s not inconceivable that you and your friends in LA are all thinking of the same 22 people with breakthrough COVID. (15/n)
#TeamPete! Do you like smart Midwesterners running for mayor? Do you like progressive problem solvers who believe in relational organizing? Do you like blue and yellow as a color scheme?
Then join me and support @GaviBegtrup for Mayor of Cincinnati! 1/