Thread by @davidwdowdy

A 🧵 for non-scientists on vax & boosters, using data from @KCPubHealth.

Seattle shows us "case relative risk", comparing unvax'd vs vax'd, over time (bit.ly/3ESvUqV).

Think of this as "level of vax protection".

Since late July, it's been stable, even going up.

Think of this number as "how many times more protected you are vs COVID if vax'd vs unvax'd."

There are 2 factors likely to affect this.
1. How long since your last shot (waning)
2. Level of exposure in the community (when exposure is intense, vax may not prevent all infections)

From mid-April to mid-May, "protection level" went up because:

1. People were getting their 2nd shots (upper right, dark bars = 2nd doses given).
2. Exposure levels were going down.

By May 16, vax'd folks were 20x more protected from getting COVID than unvax'd, on average.

Then, from May 16 to July 26, this "protection level" fell to 4x because:

1. The short-term effect of the 2nd shot wore off.
2. Exposure levels picked up (July 26 was about the steepest rise in cases in Seattle, upper right).

But what has happened over the last 2 months as exposure levels have started to fall again?

Protection levels picked back up, to 7x.

This means vax protection is not waning much in the population overall.

(Worth also saying that protection level vs hospitalization is 44x.)

So what's likely to happen if you are vax'd and get a booster?

Your level of protection will likely go up in the short term, maybe back up to a 20x level.

But what's not clear is whether that protection will come back down to ~7x level, or stay up higher.

If it stays up, great. But if it comes back down, will likely happen over the next ~2 months.

So if we have another surge in Dec, it might be nice to get a booster then, rather than now (when cases are falling).

Meaning if you were vax'd in May, makes sense to wait to boost.

All to say:
In the real world, vax still works really well.
Cases are starting to go down in most places.
So if it's been >6 months & you're at risk, reasonable to get a booster. If not, reasonable to wait.
But if you haven't gotten those first 2 shots, there's no better time.