> Because they have and broadly agree that a fourth vaccination provides benefits against hospitalization (though not infection) for older people

That's a pretty conditional statement. We're also not on dose four, we're on dose...seven? And young, healthy people are still being mandated to get these things.

I stand by my comment: the studies you are citing are all low-quality, observational data, in older populations. I'll just start working down the list from the top...

> Bar-On YM, Goldberg Y, Mandel M...

Garbage study.

Observational. Confounded (vaccine-seeking behavior). Old people (>60). No control (the "internal control" was not a control).

> Magen O, Waxman JG, Makov-Assif M...

Obeservational study. Confounded (vaccine-seeking). Effect size was miniscule:

"In days 7 to 30 after a fourth vaccine dose, the difference in the absolute risk (three doses vs. four doses) was 180.1 cases per 100,000 persons (95% CI, 142.8 to 211.9) for Covid-19–related hospitalization and 68.8 cases per 100,000 persons (95% CI, 48.5 to 91.9) for severe Covid-19."

That's a difference of 0.18% for hospitalization, in a population of people over 60.

> Gazit S, Saciuk Y, Perez G

Observational study. Older population (60+). Confounded (vaccine-seeking). Found that effectiveness against infection was short-term, and that the fourth dose had very little impact on severe disease or hospitalization.

"vaccine effectiveness against infection varied over time, peaking during the third week with a VE of 64% (95% CI: 62.0%-65.9%) and declining to 29.2% (95% CI: 17.7%-39.1%) by the end of the 10-week follow-up period. Unlike VE against infection, the relative effectiveness of a fourth dose against severe COVID-19 was maintained at high level (>73%) throughout the 9-week follow-up period. Importantly, severe disease was a relatively rare event, occurring in <1% of both fourth dose and third dose only recipients."

> Arbel R, Sergienko R, Friger M

Observational study. Older population (60+). Confounded (vaccine-seeking). Tiny effect size (hospitalization in 4-shot cohort: %0.08; 3-shot cohort: 0.2%)

"A total of 563,465 participants met the eligibility criteria. Of those, 328,597 (58%) received a second booster dose during the 40 day study period. Hospitalization due to COVID-19 occurred in 270 of the second-booster recipients and in 550 participants who received one booster dose (adjusted hazard ratio, 0.36; 95% confidence interval (CI): 0.31–0.43). Death due to COVID-19 occurred in 92 second-booster recipients and in 232 participants who received one booster dose (adjusted hazard ratio, 0.22; 95% CI: 0.17–0.28)."

> Regev-Yochay G, Gonen T, Gilboa M...

Small sample size (N=1050). Not blinded. Not randomized. Lower PCR testing adherence in control group. Short follow-up period. Overall insignificant clinical effect:

"25.0% of the participants in the control group were infected with the omicron variant, as compared with 18.3% of the participants in the BNT162b2 group and 20.7% of those in the mRNA-1273 group. Vaccine efficacy against any SARS-CoV-2 infection was 30% (95% confidence interval [CI], −9 to 55) for BNT162b2 and 11% (95% CI, −43 to 44) for mRNA-1273"

In other words, the VE confidence interval crossed zero for both vaccines -- it's possible the extra dose made things worse.

I've run out of time and this post is getting long, but the remaining studies are no different. Is it possible that there's some tiny effect size for elderly people? Sure. But this data doesn't support shot 7 (or 6, or 5...), and it definitely doesn't support the boosters in people younger than 60.