I don’t understand how the second wave can’t be explained by increase in testing. Before only people who were sick were allowed to be tested, who correlate more with hospital visits, which correlates more with deaths, so it more closely follows the death graph.
It used to be the case that 4.4% of people you tested had COVID-19.
Now you test more people, who look less risky on average, and find that 7.4% of people you test have COVID-19. The people you would have tested in the old days are the riskiest subgroup, so more than 7.4% of them have COVID-19.
So it sure seems like the infection rate went up by at least (7.4/4.4) = +70%.
US positive test rate is up from 4.4% to 7.4%: https://coronavirus.jhu.edu/testing/individual-states
It used to be the case that 4.4% of people you tested had COVID-19.
Now you test more people, who look less risky on average, and find that 7.4% of people you test have COVID-19. The people you would have tested in the old days are the riskiest subgroup, so more than 7.4% of them have COVID-19.
So it sure seems like the infection rate went up by at least (7.4/4.4) = +70%.