Originally Posted by
st8dm
It's not clear what is happening for those who
a) connect from Schengen to Non-Schengen and vice-versa
you "cross the border" but not to Poland...
your are only transiting
b) have booster (3x doses)
many authorities require either a test or the booster
A. No test if you have a connecting international flight departing within 24 hours. Show your itinerary to the Immigration officer to get an exception. No itinerary = bad luck = test needed.
B. Booster is not mandatory.