Around the end of January I posted this table and about half or less of the states were showing deceleration of their COVID case growth rates. This could be seen in the dIROC_confirmed column where negative numbers are deceleration and positive numbers are acceleration. Now, about 12 days later, every state has negative growth acceleration and the overall growth rate numbers are much lower. This happened very quickly. You can see that Arizona — who had the largest growth rate in the country as of 1/31 — now is much lower and has the largest deceleration number in the US.
As winter weather patterns still differ across the US, I’m curious if this reflects growing numbers of COVID vaccinations
Below are the Arizona numbers by county. One interesting point to note is that Maricopa County has a higher deceleration number and a lower overall case growth rate than Pima County. This is counter-intuitive because Pima County has enforced much more restrictive COVID policies during the entire outbreak. I have heard (but haven’t researched) that vaccines are easier to get in Maricopa County due to a more efficient rollout by their County Medical Office. Perhaps this is reflected in these numbers?