Just an observation about the “4th wave”. The first 3 waves had similar upwards slopes in the epicurves (yellow lines at left).
This curve, so far, for the supposed 4th wave, has a slope about half that of the prior waves. Of course, it is probably too early to tell, although the period of rise (compared to period of rise on prior events) suggests the pattern may already be evident. That is, the 4th wave growth is at half the rate of the prior peaks.
It is also possible, as some “experts” have suggested, that this 4th ripple or wave is due to increased testing of asymptomatic K-12 and college students as schools and colleges resume activities after spring breaks, or after a year long closure. (However, hospitalizations and ICU bed usage have also increased which seems to negate that hypothesis.)
I have seen some models and some “expert opinion” that this 4th wave ripple may peak by mid- to late-April – and then the curves will resume their downward trajectory as we get into May.