Seasonality is just one of many factors that affect the spread of COVID. Blindly comparing the situation now with one year ago really doesn't make any sense.

Vaccine efficacy against infection has been measured in a lot of studies, for example [1, 2, 3]. It has also been shown that being vaccinated reduces viral loads after infection, even with the delta variant [4, 5]. There are also a few studies on household transmission [5, 6] that show that transmission between vaccinated individuals is significantly less likely.

[1] https://www.nejm.org/doi/10.1056/NEJMoa2114228

[2] https://papers.ssrn.com/sol3/papers.cfm?abstract_id=3949410

[3] https://www.science.org/doi/10.1126/science.abm0620

[4] https://www.nature.com/articles/s41591-021-01575-4

[5] https://www.thelancet.com/journals/laninf/article/PIIS1473-3...

[6] https://www.thelancet.com/journals/lanwpc/article/PIIS2666-6...

Last year had the original variant and this year delta. In addition last year most countries already were in lockdown since October while this year lockdowns just started mid December. In addition there are still less hospital space taken by covid patients conpared to last year, although the problem here is also mass resignation of medical staff.

How is that not much better on all fronts?