NEW DELHI: Delhi recorded 509 fresh Covid-19 cases in a single day on Wednesday breaching the 25 per cent positivity rate mark.The positivity rate stood at 26.54 per cent, while no new fatalities were logged.Delhi had recorded 521 cases on Tuesday, the highest single-day rise since August 27 last year, and one fatality, PTI quoted data shared by the city health department.The positivity rate stood at...