1. The C-19 Vax which was approved for children 5-11 years of age is for Emergency Use which is really bothersome because the vaxxine has not been approved by the FDA and is still being studied.

2. The Pfizer 5-11 vax is not just a mini dose of the adult version. It DOES contain other ingredients than the full size dose.
While in small doses,
tromethamine and tromethamine hydrochloride are added to this 5-11 vax.

3. Here is the Pfizer 12+ data for comparison.

4. It's been fact checked and it looks like they tried to discount it partly as just a stabilizing pH buffer to make it easier for storage.
tromethamine and tromethamine hydrochloride

5. A little info I found on tromethamine and tromethamine hydrochloride.