When to Get the Booster?

By admin
Let’s say you’re planning on getting a covid booster

this fall
DATE

: when’s the best time to get it? The updated boosters (

targeting the

XBB
ORG

lineage ) have been out since

mid September
DATE

, so there’s not a new vaccine to wait for. Instead, I see the choice as balancing

two
CARDINAL

considerations:

If you get it too soon it might have worn off too much by the time you most need it. But if you’re too late you might get infected in the meantime.

As a

first
ORDINAL

approximation, you probably want to have the strongest protection when local levels be at their highest. When would that be? Wastewater monitoring is pretty good for this sort of thing because it’s not dependent on people getting tested. Here’s what I see on

Biobot
WORK_OF_ART

:

It looks like

2020-2021
DATE

and

2021-2022
DATE

were strongly concentrated around

New Years
EVENT

, and

2022-2023
DATE

less so. On the other hand,

2023-2024
DATE

so far is following a trend very close to

2021-2022
DATE

, so perhaps it will be up for the holidays again?

The other key question here is how quickly the vaccine wears off. It looks like the most recent meta-analysis here is

Menegale
PERSON

et.

al 2023
PERSON

, which found effectiveness decreased quite rapidly against

Omicron
ORG

(and everything now is a kind of

Omicron
ORG

):

They estimated a half life of

111d
CARDINAL

[

88
CARDINAL

-115d]. This means that if you got a shot on

the first day
DATE

they were made available

this year
DATE

(

2023-09-12
DATE

) you’d be down to

50%
PERCENT

[

42-51%
PERCENT

] effectiveness at

New Years
EVENT

. I wish the

CDC
ORG

would be more transparent about their reasoning so we could tell whether this was on purpose…

At this point I’d love to see a calculator that lets you put in when you last got a booster (or had covid) and then combined the

half
CARDINAL

life data with the historical seasonality data to identify the covid-minimizing time to get a shot. It could even allow you to specify dates you want to not be sick for, or not get sick during, along with how important it is to you.

Unfortunately this calculator doesn’t exist, so we’ll have to eyeball it. I think most people would like to avoid infection around

Thanksgiving
DATE

and

Christmas
DATE

, historically high-infectious times that we especially don’t want interrupted by covid and during which we’re much more likely than usual to be getting together in large multigenerational groups. Getting a shot

two weeks
DATE

before

Thanksgiving
DATE

,

2023-11-09
DATE

, would have you at most protected for

Thanksgiving
DATE

, and then still

82%
PERCENT

[

78-82%
PERCENT

] of peak protection at

Christmas
DATE

. If more worried about infecting other people than getting infected yourself, such as if you’re younger but visiting older people, subtract

a week
DATE

to model that you’re trying to prevent infection in

the week
DATE

leading up and not during the holiday.

There are a lot of person-specific factors that could affect your decisions. For example, you might be about to travel to see an elderly relative or have an infant, in which case sooner is likely better. Or maybe you had covid recently or have something super important to you later in the season, in which case later could be better. In my case we’re doing

Thanksgiving
DATE

early with my wife’s family, leaving

Boston
GPE


2023-11-09
DATE

, so I’m thinking

two weeks
DATE

before that, less a week for being mostly worried about infecting other people, so around

2023-10-19
DATE

.

Anything I’m missing?

(I do think it’s worth most people getting the booster, even considered selfishly: I’d much rather suffer side effects at a time of my choosing than cancel holiday plans.)