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פרופ' אייל שחר Profile picture
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8 Aug, 5 tweets, 1 min read
1/
 They are at least incompetent.
The analysis in the post is valid. What CDC is doing here corresponds to the proportional mortality ratio (PMR) in epidemiology. (You can read about it in the textbook "Modern Epidemiology").
>>
2/
 I will quote one sentence from that book:

"An implicit assumption of a proportional mortality study is that the overall death rate for categories other than the ones under study is not related to the exposure".
>>
3/
 Translation, for AE= death:

An implicit assumption of the CDC computation is that the overall AE rate for categories other than death is not related to COVID vax. Which means that the effect of COVID vax on all other AE is not different from the effect of other vaccines
>>
4/
 That assumption is obviously false.

Therefore, the CDC computation cannot validly detect safety signals.

Either their epidemiologists need some training in methodology, or... (read the post).
@SternShahar

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More from @prof_shahar

פרופ' אייל שחר Profile picture
8 Aug
1/6
 A scary thread on case-reports.
@barakshalev
2/6
 A case-report is part of medical research.
Its weaknesses: very small sample (n=1), no estimated effect.
Nonetheless, it is research.
How come?
It is an observational study and there is “sort of” control.
3/6
 The observer sees something “unusual”, “surprising”.
Q: what is “surprising”?
A: contrast with expectation
Q: where does “expectation” come from?
A: from past experience.
That past experience is the “control”
Read 6 tweets
פרופ' אייל שחר Profile picture
7 Aug
1/
 Now that estimated VE for severe COVID is down to 70-80% from those false estimates of >95%, we are still left with cardinal questions:

1. Still biased?
2. What is the effect of V on all-cause hospitalization/death?

2/
 Still biased?

What are the characteristics of unvaccinated elderly?
Are there shared causes of V status and health outcomes?
Are those unvaccinated elderly (~10%) exchangeable with their vaccinated counterparts (90%) on key health-related variables?
3/
 For example, is the proportion of frail elderly similar in those populations?

All these questions convey a single concept in epidemiology: Confounding bias.

Example: if frail elderly make up 20% of unvaccinated but only 10% of vaccinated, true VE is lower.
Read 4 tweets
פרופ' אייל שחר Profile picture
6 Aug
1/
 Cancelled my subscription to Ha’aretz after they rejected my paper on Sweden (published on Medium). (They were scared.)

1. I/others analyzed published VE studies from Israel and pointed to evidence of biases & over-estimation

2. They claimed ~95% VE. False for all endpoints.
2/
 3. Little/no VE for infection.

4. And it is not just waning, if true. (Ab levels decline after natural infection, too, but protection is not lost. Memory cells play a role in re-infection.)

5. VE for severe disease is currently 70-80% at most (and still possibly biased).
3/
 6. Vaccine has side effects, including deaths. They never report effects on all-cause deaths/hospitalizations. Why?

7. Now 3rd dose vaccination with little to no empirical basis and numerous reasons for concern. Vaccination during a rising wave is a dangerous experiment.
Read 5 tweets
פרופ' אייל שחר Profile picture
22 Jul
1/
 They claimed that lockdown before the peak terminated the rise.

They were wrong. False claim.
Refutation: Sweden & South Dakota (for example).

Now they claim that mass vaccination "decoupled deaths from cases".

2/
 They are wrong again. False claim.
Refutation: Sweden & Netherlands (for example).

Let’s see what happened there in recent months.
3/
 Here is an impressive case wave in Sweden & Netherlands, which showed up half way through the decline in the winter wave.
Read 7 tweets
פרופ' אייל שחר Profile picture
13 Jul
1/
 Israel: another paper on VE
jamanetwork.com/journals/jama/…
Count of cases is very confusing:

2/
 Trying to split a total of 243 (eTable 1) into mutually exclusive categories of vaccinated and reconcile with a flow chart (Figure 2, with additions).

No clear understanding how the numbers are split.
3/
 However, it is clear to me that the data are hiding excess risk between dose 1 and one week after dose 2.

Likely >2-fold, (1.3-fold under the most conservative counting).
Read 4 tweets
פרופ' אייל שחר Profile picture
9 Jul
1/
 Scared by Delta wave? Read this thread.
Is Delta endemic wave that would have gone unnoticed in normal times?

Projections (& some philosophy at the end)

Key points:
Most COVID deaths are 60+.
Trend in elderly is the key - not all ages, not younger.

2/
 Here is what we see:
Continued divergence between infected vulnerable and non-vulnerable (by age).
Was fairly parallel in winter.
This divergence is the most important difference between current (summer) wave and winter wave.

coronavirus.data.gov.uk/details/cases?…
3/
 Growth rate of moving average has been declining since June 28 (in both age groups)
Last data point: July 4.
Peak case wave at ~1.
Mid-July?

See detailed graphs here, by narrow age groups
Read 11 tweets

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