1/
Peer review (unsolicited)
Another analysis of Israel data on vaccine effectiveness. Fully vaccinated vs. unvaccinated
Observation period: Jan 24-Apr 3
Bottom line: again, likely over-estimation of effectiveness.
thelancet.com/journals/lance…
2/
Over the study period:
1)People shifted from unvaccinated to fully vaccinated.
2)Rate of infection was declining (peak Jan 20)
3/
Distribution of unvaccinated on the calendar is shifted to the left (time of HIGHER infection rate)
Distribution of vaccinated is shifted to the right (time of LOWER infection rate)
So, part of the difference between vaccinated & unvaccinated is due natural wave decline.
4/
Authors try to attribute the decline to vaccination.
Unconvincing.
All waves (and previous wave In Israel) follow that trajectory. Peak & decline.
Certainly, cannot attribute the beginning of the decline to vaccination rates.
Bar graph shows weekly cases. Image
5/
Of course, authors were aware of time trends. Model included calendar week as covariate.
BUT, see table from article. Estimates of effectiveness are nearly identical (unadjusted vs. adjustment), implies no confounding by the wave trend (or anything else). That’s unexpected. Image
6/
(Note that vaccinated were older, and older vaccinated earlier, but unadjusted/adjusted are similar in each age group).
7/
What is the explanation?
Either no confounding, somehow
or
Modeling calendar week as a covariate did not take care of confounding by the time trend.

Most likely the second.
8/
Here is someone’s better analysis, accounting for time trend.
lockdownsceptics.org/2021/05/07/stu…

Lastly,
1)What happened in days 1-14 of the 1st dose?
2)Again, no estimates for all-cause deaths.

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More from @prof_shahar

1 Apr
Thread: US excess death
1/
Rough estimation of US excess deaths, Oct 2019-Sep 2020 (“flu year”)

Impact of recent winter belongs to “flu year” Oct 2020-Sep 2021

(“Flu year” avoids arbitrarily split of winter mortality between two calendar years.)

At the end: Sweden
2/
Inference derived from just 7 “flu years” (shown in rectangle) + heuristics.

Counts of all-cause deaths obtained from a table in this tweet.

Image
3/
Notice a pattern: a year of “high” mortality is followed by a year of lower/similar.

Pattern disrupted in 2017/2018, severe flu season. Should have been lower/similar to 2016/17.
Estimated flu deaths: 61,000 ImageImage
Read 10 tweets
18 Mar
1/ Important question: Once infected, what is the effect of vaccination status on death/severity?

Here is relevant statistics from Israel data.

Disturbing observations on the early period after 1st dose. Image
2/ Table shows rate of death & severe disease, since the vaccination campaign began.

Notice that risks are higher in vaccinated than unvaccinated. That’s misleading. At any time, vaccinated were older than unvaccinated (and older, on average, in sequential vaccination groups.) Image
3/ The phenomenon is called confounding. Illustrated in a causal diagram. All comparisons are not valid. They don’t estimate effects. Image
Read 12 tweets
16 Mar
1/
Theories & evidence of bias in Israel data on vaccine effectiveness.
nejm.org/doi/full/10.10…

Theories:
1. Important endpoints (hospitalization, severe illness, death) included many patients with incidental positive PCR
2. Preferentially in unvaccinated
2/
All figures taken from Supplementary Appendix Figure S3. (The Y-axis scale seems wrong, but I assume it is just a labeling error)

Key figure: Time to hospitalization

Most patients were hospitalized within 1-2 days (!) of a first PCR swab that was found positive

Unexpected. Image
3/
Typical course much longer: symptoms->test->worsening symptoms-->hospitalization

What happened?

Many patients were likely tested in the ER. They showed up in severe enough condition, for which no outpatient PCR was done. Thus, their condition on admission was not COVID
Read 10 tweets
11 Mar
1/
What is vaccine effectiveness in the most vulnerable population? Is it indeed >90%?

What is happening shortly after dose 1 of the vaccine?

A large cohort study (Denmark) of nursing home residents (and health care workers) provide interesting answers

medrxiv.org/content/10.110…
2/
Retrospective cohort during vaccination campaign, which coincided with winter wave

Key points:

Wave trajectory (date) was a major confounder.

Estimated effectiveness of full vaccination much lower in nursing home residents (64%) than health care workers (90%)
3/
Not surprising. The claim that effectiveness is just as high in the elderly does not fit knowledge of immune response with aging.

See here, for example.
Read 7 tweets
10 Feb
10 שאלות מטרידות שמותר לשאול, בינתיים:

1. מדוע נמחקת הנורמה שאין לכפות על הפרט, ישירות או בעקיפין, התערבות רפואית?

2. מדוע נמחקת נורמת החיסיון הרפואי לפיה מידע מזהה על טיפול/היעדרו שייך בלעדית לפרט?
3. מדוע אישר ה-FDA בנוהל חירום (בניגוד לסטנדרט מעקב) חיסון לאוכלוסייה שאינה בסיכון חריג? (מקובל לגמרי אישור בנוהל חירום לאוכלוסייה בסיכון.)

4. מדוע התקשורת בארץ ובעולם לא מציגה לציבור הערכות שיעורי תמותה בקבוצות גיל צרות, במקום לדווח אנקדוטות?
5. האם חסינות לאחר חיסון (באמצעות זיהוי חלבון הספייק) תגן בפני מוטציות באותה אפקטיביות של חסינות נרכשת לאחר הידבקות?

6. מה קורה במערכת החיסון כאשר נדבקים בסמוך לחיסון הראשון ומערכת החיסון מזהה בו זמנית את הנגיף ואת חלבון הספייק שלו על תאי גוף? האם יש תגובת-יתר חיסונית?
Read 6 tweets
8 Feb
יש יותר מידי משתנים בתמונה, מכדי לומר משהו בוודאות. למשל: אפשרות הידבקות בעת החיסון, פגיעות-יתר בימים שלאחר החיסון הראשון, התפרצויות בבתי אבות שדעכו (קשורות לחיסון?), מהלך גלים שונה טבעית בגילאים שונים (מסיבות לא תמיד ברורות). trajectory שונה (מלכתחילה) של קשים-חדשים צעירים.
כאן רואים מורפולוגיה "משתנה בערך מונוטונית" עם הגיל שמתאימה בעיקר למהלך טבעי יותר מאשר לדיכטומיית חיסון/לא חיסון.

האם מעורבבים כאן, בין היתר, אפקט החיסון + הדבקה/רגישות יתר להידבקות סביב החיסון?

באפידמיולוגיה זה קרוי מודיפיקציות של אפקטים. מסובך מאד כאן

quantitatively.club/wp-content/upl… Image
לדעתי אפקט מיטיב של החיסון היה מאוחר מכדי להשפיע משמעותית על תאריך היעצרות הגל וגובהו. התחיל בערך במחצית הדרך לשיא כמו "אפקט הסגרים הקודמים".

יש כמובן מומחים שאצלם הכל ברור. יש משתנה אחד והוא חזות הכל.
Read 4 tweets

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