I had to go down to the footnotes

"An example is Riverside, Calif., where rents have climbed more than 20 percent over the past five years – yet HUD’s homeless count has fallen. Next door to Riverside is the Los Angeles CoC, where the homeless count has risen 73 percent in a similar five-year span – some of which can be attributed to factors beyond Los Angeles’ poverty rate and rental market. Spillover from places like Riverside is a possibility."

~ C. Glynn

https://www.zillow.com/research/homelessness-rent-affordability-22247/ 

to find the definition of "CoCs."