New research shows that only 10% #Omicron cases are in ppl who have gotten #COVID19 #Booster.

This may be MISINTERPRETED as:

"Only 10% of people w/ #BoosterDose get #OmicronVariant"


#BoosterShots are 90% effective"

Not that simple! READ ON!


First, this is NOT a critique of the study (currently a pre-print).

Researchers at @MethodistHosp who did this provided a VERY valuable piece of info and are not making any inappropriate claims. Great work!

It's just that it's easy for public/media to misinterpret results!

Paper reports on a total of 1313 #OmicronVariant cases in the Houston, TX area.

See table below:
~49% of cases in those not vaccinated (0 or 1 does)

Of those #Breakthrough cases,

535 cases w/ 2 #vaccine doses
140 cases w/ 3 doses (i.e., booster) Image

From these, we can accurately say that in THIS SAMPLE, only 10.7% of people w/ #Omicron were those who had gotten a booster (140 / 1313 = 10.7%).

May initially seem like #Breakthrough is uncommon if you have a #booster.

But, we MUST consider how many people are #boosted

Let's do an analogy.

- Let's say 10% of the population has a pet goldfish
- Assume that goldfish possession is unrelated to #COVID #OmicronVirus risk

Then, we would expect only ~10% of Omicron patients to be goldfish keepers.

Do we conclude goldfish prevent #Omicron?

To see how effective a booster is at preventing Omicron, we need to know what the vaccination + booster rates.

We'll do some ROUGH estimates. #epitwitter

These data are from Nov 27 - Dec 20, 2021.

As of then, 58.3% of Houston metro had 2 doses.


I couldn't easily find booster rate for Houston specifically, but it is available for the state of Texas as a whole - 15% as of Dec 23.

For purpose of this thread, we'll use that.

58.3% vaccinated
~43.3% w/ 2 dose
~15% w/ 3 dose


Now, we can attempt a *ROUGH* estimate at how many people we are in each group.

I used Harris County, which has an estimated population of 4,731,000.

This means, there are ABOUT:
1.22M unvaccinated
1.27M w/ 2 dose
440K w/ 3 dose



Total positives in Harris County from 11/27 to 12/20 is 20827.

Total positive #COVID (all variants) tests reported in paper is 20152.

So, theoretically, this dataset represents 97% of the case count (and population?, thus 4.5M) in Harris County.


I must emphasize that all of the above are VERY ROUGH ESTIMATES w/ multiple assumptions (i.e., Harris County doesn't represent entire Houston Metro area (>7.1M), etc.)

But, good enough to obtain very basic odds ratios regarding how well the vaccines work vs. #omicron.

The paper reports data on positive tests for #Omicron, #Delta, and #Alpha variants.

We don't know how many people are truly positive for any of these, but weren't tested. So, in my table, I list them as "Not Known Positive" rather than "Negative."

#CovidVaccine Image

From this, we can compute some risk ratios for the odds of getting Omicron.

Unvaccinated vs. 2 Dose = 1.25
Unvaccinated vs. 3 Dose = 1.65
2 Dose vs. 3 Dose = 1.33

So, there's a 33% greater risk of getting #OmicronVariant if you have 2 Dose compared to if you have 3 Dose

If we do this for Delta, the ratios are WAY different
(Note, OR and RR produce nearly identical results).

Unvaccinated vs. 2 Dose = 3.39
Unvaccinated vs. 3 Dose = 31.2
2 Dose vs. 3 Dose = 9.2

#BoosterShots appear VERY effective vs. #DeltaVariant - 9.2 greater than 2 dose!

Against, #alpha (the "original"), the paper just lists #FullyVaccinated, so we can't break down 2 vs 3 dose. But the RR is >31x greater for unvaccinated vs. #vaccinated!


All of these are estimates, based on some assumptions (described in tweets 6a-6e). But, even if we tinker w/ the numbers, they hold up.

For ex, if we do Harris county population (7.1M) or if we say Methodist only represents 10% (not 97%) of cases, risks remain similar.

So, looking at the numbers, I think it is clear that:

1. Getting a #boosterprik does reduce the risk of #Omicron substantially (33%) compared to having only 2 doses (Tweet 7b)


2. The #BoosterJab is WAY more effective against #DeltaVariant (>800%, Tweet 7c)

There's plenty of limitations (1 hospital system, age and comorbidities not considered, assumptions in calculations, early into Omicron surge, etc.).

But, hopefully this provides some insight to answer the question of how effective is the booster vs. 2 dose against Omicron?

If you found this helpful (or found others misinterpreting the data), please SHARE and RETWEET.

If you see a problem with my numbers, calculations, or assumptions that would change the conclusions, please let me know!


• • •

Missing some Tweet in this thread? You can try to force a refresh

Keep Current with James Smoliga, DVM, PhD

James Smoliga, DVM, PhD Profile picture

Stay in touch and get notified when new unrolls are available from this author!

Read all threads

This Thread may be Removed Anytime!


Twitter may remove this content at anytime! Save it as PDF for later use!

Try unrolling a thread yourself!

how to unroll video
  1. Follow @ThreadReaderApp to mention us!

  2. From a Twitter thread mention us with a keyword "unroll"
@threadreaderapp unroll

Practice here first or read more on our help page!

More from @jsmoliga

1 Mar 21

@US_FDA approved the #Qcollar jugular compression device to "protect athletes' brains during head impacts."

This decision was based on VERY FLAWED DATA and does NOT demonstrate the safety or effectiveness of the Q-collar.

Read detailed thread⬇️


Here is the text from the @FDADeviceInfo press release.

If you don't understand the highly nuanced #MRI technique known as DTI, these results sound straightforward and convincing.

THEY ARE NOT. Don't be fooled by these numbers!🤔

I will dissect these in the thread below. Image

"No significant changes" is based AVERAGE response, not individual.

First, an easy-to-understand analogy below.

If half the sample experiences an increase and half experiences a decrease, they can cancel each other out to falsely suggest "no change" when one does exists! Image
Read 24 tweets
10 Aug 19
Does the woodpecker-inspired #Qcollar protect the brain & prevent #concussion?

Take 3 minutes to read this fully referenced thread presenting evidence that a jugular compression collar is unlikely to keep athletes safe

Please SHARE, help inform others!


The #Qcollar is based on the idea that jugular compression increases blood in the brain to create a "bubble wrap" effect, which prevents the it from bouncing around inside the skull.

According to the company, this mechanism is found in Nature.

From the company's promotional video, the device is justified based on reducing brain "slosh" by:

1) Replicating the animal adaptations (see 18:00 in video)
3) Replicating effects of "higher altitude" exposure (see 21:57, again at 36:00)

Read 57 tweets

Did Thread Reader help you today?

Support us! We are indie developers!

This site is made by just two indie developers on a laptop doing marketing, support and development! Read more about the story.

Become a Premium Member ($3/month or $30/year) and get exclusive features!

Become Premium

Too expensive? Make a small donation by buying us coffee ($5) or help with server cost ($10)

Donate via Paypal

Or Donate anonymously using crypto!


0xfe58350B80634f60Fa6Dc149a72b4DFbc17D341E copy


3ATGMxNzCUFzxpMCHL5sWSt4DVtS8UqXpi copy

Thank you for your support!

Follow Us on Twitter!