Three big lulls so far, but it keeps coming back. Hospital admissions reflect severe cases, and those are well above the lowest levels seen. Deaths remain low, reflecting the combination of vaccination and the current variants being less lethal.
Understanding of the metabolic mechanisms of long COVID is improving. It’s much less mysterious than it was a year or two ago. It’s been known for a while to be an inflammation disease that can be seen in MRI scans. Now, the mechanism which causes inflammation is starting to be recognized.
I don’t know that evidence supports this. Whatever arguable effectiveness vaccines had against the initial Wuhan strain, it was almost certainly magnified in presentation to the public; it is widely accepted - even by the most ardent advocates of of their miraculous effectiveness - that the duration of their effect was measured in months, not years. Thus, I can’t see how any residual vaccine effect can be cited for decreased virulence of present infections.