(emphasis mine)Short english summary: 7 germans on a trip through South Africa all catched Omikron.
No vaccine protection is perfect. While these folks may have been vaccinated, most of South Africa isn't - under a quarter of the population is fully vaccinated!
So, yes, if you go about your business like nothing is wrong, and metaphorically steep yourself in a bath of virus for a prolonged period, yes, you are still going to catch it!
Being vaccinated is not a free pass to engage in risky behavior.