In a letter to State Chief Secretaries, Union Health Secretary Preeti Sudan said, earlier districts were designated as hotspots or red-zones, orange zones and green zones primarily based on the cumulative cases reported and the doubling rate.
Since recovery rates have gone up, the districts are now being designated across various zones duly broad-basing the criteria.
She said, a district will be considered under Green Zone, if there are no confirmed cases so far or there is no reported case since last 21 days in the area.
She highlighted that based on field feedback and additional analysis at state level, states may designate additional red or orange zones as appropriate.
However, they may not relax the zonal classification of districts classified as red or orange. She highlighted the necessary action in red and orange zones to break the chain of transmission of virus.