While the United States has made a U-turn, India is on a very worrisome trajectory

Why did the US make a U-turn in new cases?
It isn't entirely clear but there are a few factors
The surge was driven by the 3 most populous states (CA, TX, FL and AZ)
1. @trvrb's thread addresses the concept of a relative herd immunity in hard-hit states https://twitter.com/trvrb/status/1291860670439280640

2. @K_G_Andersen makes a key point that it's not necessarily state-wide because there are now at-risk groups with very high exposure in these places

3. The modeling by @youyanggu, who predicted the U-turn and invoked relative herd immunity, is very encouraging w/r to continuation in decline of cases and deaths
https://covid19-projections.com 
Still takes us to ~230,000 deaths by end of October

4. The other glaring factor is the reduction of testing, which parallels thediagnosis of new infections. This is just the opposite of what is needed now to get the US pandemic under control.
Graph @COVID19Tracking