The Nagpur MunicipalCorporation's 'contact tracing system' was an effective mechanism to track down close contacts of COVID-19 patients and contain the spread of the pandemic, a senior civic official said on Tuesday.Municipal commissioner Tukaram Mundhe said it was crucial to identify high-risk contacts of COVID-19 patients and break the chain of infections.The civic body has developed a contact tracing system, under which as soon as a person tests positive for COVID-19, a rapid response team identifies, tracks down and picks up close contacts of the patient, the civic chief said."We have deployed 48 RRT teams in 38 wards of the city, who immediately probe and identify patients' close contacts and shift them to quarantine facilities," he said.Citing an example, Mundhe said when 17 people from the district tested positive on Sunday, 79 of their close contacts were tracked and quarantined."We also get information about high-risk contacts from third party sources, wherein civic personnel speak to locals to track down suspect cases from the area where positive patients are found," Mundhe said.The system was effective, as almost all high-risk contacts of COVID-19 patients have already been quarantined, he said.