this appears to be happening in new york as well, where herd immunity in new york city is being offset (or distorted) by a rising problem in buffalo. i pointed this out looking at the italian numbers - you need to be sure that you're looking at the data in a granular enough manner, to ensure you're not misinterpreting the interference patterns.

this is going to be an expected feature of this, as things develop - very localized waves, at the city or even neighbourhood level, rather than broad waves at the state, provincial or national level.

https://www.bridgemi.com/michigan-health-watch/coronavirus-surges-grand-rapids-area-bucking-trends-rest-michigan