Delhi on Tuesday witnessed the highest single-day spike in novel coronavirus cases ever, taking the Covid-19 count in the national capital over 66,000.A total of 3,947 fresh coronavirus cases reported in the last 24 hours, the total number of positive patients in the national capital surged to 66,602, according to concerned authorities.Along with that, the death toll also increased to 2,301 after 68 more virus-related fatalities were reported in the national capital since Monday, the authorities added.It, however, added the cumulative death figures refers to fatalities where the primary cause of death was found to be Covid-19, as per the report of the Death Audit Committee on the basis of case sheets received from various hospitals.There.