New Delhi, Nov 28 : The Centre on Sunday wrote to the states and UTs over the possible threat of new Covid variant B.1.1.529 which has been designated as the 'Variant of Concern' (VOC) by the World Health Organisation. The Centre has urged states and UTs to do rigorous surveillance of international passengers. "ln view of the possible threat that this VoC can pose to the nation, it is imperative that the intensive containment, active surveillance, increased coverage of vaccination and Covid Appropriate Behaviour must be enforced in the field in a very proactive manner to effectively manage this VoC", said the letter to the states and UTs. It is essential that the disease surveillance network in the country is geared up for rigorous follow up of all international travelers from all countries especially countries designated as "at risk". The letter said, there is already a reporting mechanism for obtaining past travel details of passengers coming through international flights. "This should be reviewed at your level and the protocol provided by this Ministry should be strictly ensured including testing on disembarkation of international travelers coming from 'At Risk' countries and sending all positive samples for genome sequencing to INSACOG Labs in a prompt manner." The Centre has also asked the states and UTs to enhance the Covid testing and strict monitoring of the hotspots. "ln all such hotspots saturation testing and sending of positive samples quickly for genome sequencing to designated INSACOG Labs must be ensured in collaboration with Department of Biotechnology (DBT), Govt of lndia and National Centre for Disease Control (NCDC). States should keep a close check on the emerging trend of cases and the positivity rate in an area and quickly delineate hotspots for effective containment of Covid-19", said the letter. The states should aim at achieving positivity rate below 5 per cent while focusing on increasing the number of tests and share of RT-PCR tests to aid in early identification. The Centre has also asked the states for regular press briefing for promoting Covid appropriate Behaviour and vaccination. "INSACOG has been established to monitor the circulating variants in the country. It is important at this juncture that states must significantly increase sampling from the general population for genome sequencing by sending these samples to INSACOG Lab network as per the policy", said the letter. With emphasis on ensuring augmentation of health infrastructure, the Centre has said state, UTs to adhere to the overarching 'Test-Track-Treat Vaccinate and Covid Appropriate Behaviour' principle to ensure stringent implementation of containment measures as per the guidelines. /IANS