New Delhi, Dec 18 : The Union Health Ministry on Monday issued an advisory to states over the fresh surge in Covid-19 cases in some states/UTs in India and the detection of the first case of the new JN.1, a sub-variant of Omicron, in Kerala. In the letter, Union Health Secretary Sudhansh Pant highlighted the need for maintaining a state of constant vigil over the Covid situation in the country. Underlining that "due to consistent and collaborative actions between Centre and State Governments, we have been able to sustain the trajectory at sustainable low rates", he said: "However, as the Covid-19 virus continues to circulate and its epidemiology behaviour gets settled with Indian weather conditions and circulation of other usual pathogens, it is important to keep the momentum going to effectively deal with the challenges in public health." The letter comes as India on Monday recorded 1,828 Covid cases. With 1,634 cases, Kerala accounted for the highest number. Looking at the upcoming festive season, the Union Health Secretary advised the states to put in place requisite public health measures and other arrangements to minimise risk of increase in transmission of the disease by adherence to maintenance of respiratory hygiene. All states have been advised to ensure adequate testing in all the districts as per Covid testing guidelines and maintain the recommended share of RT-PCR and Antigen tests. They have also been asked to monitor and report district-wise Influenza-like Illness (ILI) & Severe Acute Respiratory Illness (SARI) cases in all health facilities on a regular basis including in the Integrated Health Information Platform (IHIP) portal, for detecting the early rising trend of cases. The ministry also encouraged to increase number of RT-PCR tests and send positive samples for genome sequencing to Indian SARS COV-2 Genomics Consortium (INSACOG) laboratories so as to enable timely detection of new variants. JN.1 is a sub-lineage of the BA.2.86 Omicron variant and was first detected in Luxembourg in August, before spreading to other countries. BA.2.86, also known as the "Pirola" variant, was first detected in Denmark in July. According to the US Centers for Disease Control and Prevention (CDC) JN.1, is part of the same lineage of BA.2.86 and contains an extra spike mutation -- L455S mutation, which has immune-evasion properties. The World Health Organisation (WHO) has also asked for strong surveillance and sequence sharing, as cases are rising globally. About 68 per cent of the current Covid cases are cases of XBB sublineages and other groupings like JN.1, Maria Van Kerkhove, Covid-19 technical lead at WHO, said in a video message, posted on X. /IANS