It says “from an Omicron infection” - which was expected since it is much more transmissible as well as the mutations that evade vaccine.First line of this article
‘Two doses of some vaccines offer almost no protection from an Omicron infection, although they should still greatly reduce the risk of becoming so ill you need hospital care.’
So the first 2 vaccines give you no protection (way to talk the unvaccinated round) and this third dose should reduce risk, still no guarantees there. When is the next variant due that you’ll need the fourth booster for?