NEW DELHI: Amid fear that Covid-19 positive cases – one each in Tamil Nadu and Pune could be the first cases of community transmission, the government is vigorously pursuing contact tracing in these cases to identify sources and break the chain of transmission.A 20-year-old Delhi resident in Tamil Nadu and a woman in Pune who tested positive this week had, unlike other “positive cases”, not travelled to any foreign country and have denied coming into contact with a known Covid-19 patient.Authorities are yet to establish the source of infection in these cases and if further investigation confirms their account, then the two cases will mark the worrying evidence that the virus might have spread in the community— a threshold at which a huge surge of incidence may become unavoidable. The health ministry on Saturday maintained there was no evidence of community transmission in the country, and that the two particular cases were still being investigated. Official sources said there are indications that the individuals don’t have adequate recollection of events involving them— essentially, who all they came in contact with— and a firm conclusion can be reached about the source of their infection once the “missing links have been established”.The government and health agencies in multiple states are carrying out an aggressive drive to trace the contacts of these two cases and locate people they have met, events attended by them, places they have visited, transports used by them, even co-passengers and various other minute details to establish the source of infection.