“This may be the most precarious moment that we’re facing since we have emerged from lockdown,” Chokshi said, warning the clusters could soon evolve into widespread transmission. “We will move as swiftly as the situation warrants … If this growth continues, it will turn into widespread transmission potentially citywide.”

The clusters have seen such alarming growth in the past week — and again over the past few days — that the health department says reopening rollbacks may be implemented for the first time in the city’s recovery period if progress is not made. It set a Monday deadline for that.

“The immediate scaling back of activities” would apply only to the affected ZIP codes, not citywide, the health department said Thursday evening — and could include bans of gatherings of 10 or more people, mask fines, private school and child care center closures and shuttering all non-essential businesses again.