Well, with the flu vaccinations there is always the caveat that it very often is a different strain that comes than the one you got the shot for.
As for the relative success of Eastern Europe in dealing with this...That's a bit of a mystery. All circumstances indicate that COVID should hit these countries harder than Western EU countries, as we have significantly worse healthcare systems and by and large, lower life expectancy (a.k.a an unhealthier population). Maybe the TBC vaccination has something to do with it, but my cynical reading is that there are fewer people here that are "at risk", simply because most folks with serious preexisting conditions are dead already, even without COVID.
What's really suspicious to me is that there seem to be reports that the virus was present in Europe (e.g. France) as early as November 2019, in fact I'm pretty sure that I myself caught this as early as December 2019 and then my wife early March (anecdotal, but symptoms totally check out as a mild variety of COVID in both our cases), it's just that nobody was testing for it at the time. So what gives, how come there was no apocalypse across Europe then? We've all heard the stories where a single individual at a restaurant infected tens of people in a few hours, of course we only ever know because we are testing for it and make a big deal out of it. Then there is the fact that counting COVID fatalities is an absolute patchwork of practices that varies from country to country and often little distinction is made of victims that died OF COVID instead of WITH COVID.
I'd first like to adjust my statement, Belgium is at 5% infection rate.
To go with that, I'd like to note that this virus isn't as infectious as the flu, atleast not in general. Sure a grouping in close proximity for an extended time might mean that 1 person infects the entire group, but for now it seems we averaged at 3 to 5 infections per infected at the height of this pandemic. It lies in the trade-off of being a more severe virus but being less infectious.
Indeed various nations have had the virus during the intial stages, they just never really took hold due to the low infection rate, coupled with perhaps "smart" people being infected who stayed at home to ride it out.
As for Eastern Europe, I'd venture a guess that also wealth worked in your advantage, less people going abroad on vacation, even less to dangerous places. And of the people who could go, they tend to self-isolate in their social circles, which are also better monitored on health concerns as they can easily afford a doctor and/or medications. Heck has there been any news/testing to find out the total carriers of antigens in your nation?
Still, the "second wave" might still hit, and hit hard. I'd have serious doubts about you having contracted, and passed, the virus. Group immunity is a far flung utopia and who knows what an actual full spread will do to a nations health services.
The hurricane deaths not linked to actual wind, so to speak.