Looks like the 5th wave is peaking. I thought for sure the 4th was the end, but it wasn’t. If we have a 6th wave, I predict it will occur around December 31 this year.
This is based on a simple observation: the peaks of the waves seem to come about 4 months apart (average 126 days, standard deviation 22 days).
Why are we having more waves? If COVID were not evolving, we would have reached herd immunity by now and the disease would have died out. Instead, it’s acting as if there’s a large pool of susceptible people. This means the disease dynamics depend a lot on collective human behavior.