Seasonality plays a huge role for sure. Within Europe I would be surprised if there's much variant variance. There's been a lot of summer vacation travel within Europe starting last May, so I would expect that variance would be reasonably low.

Also, EU had a rather late start with vaccination. While UK, US and Israel vaccinated lots of people by mid-April, Europe was just getting started. So, there's 4-5 month lag in terms of vaccine efficacy and Europe's summer weather and late vaccination is giving seemingly better picture at the moment.