Basanti, 71, reacts as she receives a dose of the coronavirus vaccine at a vaccination center in Karachi. — Reuters KARACHI: More than 40 cases of the Delta variant — a highly virulent Covid-19 strain that has caused devastation in India a few months back — have been reported in the city during the current month. Sources told According to the health department data, a copy of which is available with Dawn, 24 cases of the Delta variant were reported last month. The tests were largely performed at the Aga Khan University Hospital and the National Institute of Health (NIH), Islamabad. “The surge in Covid-19 across the country, particularly in Karachi is alarming, which indicates that we are in the grip of a fourth wave. The Covid-19 unit at the Indus Hospital is full and the same is the case at other major tertiary care hospitals in the city,” said Dr Samreen Sarfaraz, a senior infectious diseases expert at the Indus Hospital.