Re: The European Commission has approved the use of BioNTech-Pfizer Comirnaty, Moderna Spikevax, Novavax Nuvaxovid and Janssen COVID-19 vaccines as booster doses for persons aged 18 or over
Not sure why, but probably not enough talk in the media, definitely no push by authorities, but it's true that it's not approved as booster and almost everybody is already vaccinated here (Spain).
It's clear that it's not very well known and people are tired of covid, most don't care anymore.
It has been here for months but few were eligible. Just non vaccinated (almost non existent), immunosuppressed, and people with adverse reactions to mRNAs.