Sammie,

>Has anyone seen anything on the effects of multiple booster shots and the auto immune system? I saw something last week but I can't find it again.

German Spiegel covers Israel and Corona best in german media. No idea if available in english international version, but could be fed to Translate::

https://www.spiegel.de/wissenschaft/medizin/israel-weitet-vierte-corona-impfungen-aus-a-adb0f963-a730-45e4-a7bd-eeeaa2799a5d

https://www.spiegel.de/wissenschaft/medizin/studie-in-israel-zur-zweiten-booster-impfung-erste-ergebnisse-nicht-so-gut-wie-erhofft-a-ceb53bae-0e67-40d1-b0ab-8b09490bfac4

tl;dr:
Boost measurable on 4,
antibody hike might be even shorter lived;
they start to compare boosting 3x Pfizer with Pfizer and (as a first) Moderna hoping for better boost via heterologic
discussion on "prick any arm, however young" to "prick those arms that might be endangered" as sensible mantra

as this is very early, if you come across follow up, please share a link...

regards
thomas