A screening camp was held for immediate neighbours and contacts on Monday after four residents tested positive for Covid-19 at Labony Estate.

The building in D Block, facing the street outside, has been barricaded as a micro containment zone. With the administration trying to put a cap on the spread of Covid 19 in the township, this is the third such zone to come up in Salt Lake over the last seven days.

While the first zone was demarcated on June 24, with four houses — BF 166 to 170 — cordoned off on First Avenue, two more were added the next day. The second is in the same block, at BF 315.

Four pavement stalls have been removed due to their proximity to the first floor of the building which overlooks them. Three of the stalls, two of them selling milk and the other fruits, have been relocated but a tea stall has been asked to shut down. Tea stalls, where clients habitually take their masks off, have always been considered super spreader venues. “The lady running the stall had herself been infected with the virus last year, towards the start of the first wave,” a resident recalled.

On Monday, rapid antigen tests were conducted by the Bidhannagar Municipal Corporation on 56 people, including sweepers and stall-keepers of the area. Though the results came negative for everyone, the police is keeping strict vigil. Commissioner Supratim Sarkar himself visited the area on Saturday. PCR vans with two cops from the Bidhannagar north police station have been stationed at each of the three containment zones round the clock.

Residents are happy with the arrangement. “Labony had been majorly affected in the second wave, with a period at the peak of the wave in May seeing as many as 20-22 families testing positive around the same time,” said Sumit Sarkar, general secretary of Labony Abashik Samity. The complex has 700 flats.

At the BF Block containment zone, five members of a family had tested positive soon after another in the adjacent house got infected. “Though the first patient has recently recovered, we did not want to take a chance and included the neighbouring houses too in the containment zone,” said a police officer. The building at an extremity of the barricade houses a pre-school and offices, so is shut anyway.

North 24-Parganas has the highest number of micro containment zones in the state, numbering 83.