The Centre on Saturday wrote letters to five states and the Union Territory of Jammu and Kashmir, flagging rise in coronavirus cases in some districts amid concerns about the new Omicron variant, India Today reported.

First detected in southern Africa in November and dubbed a “variant of concern” by the World Health Organization, scientists are concerned that Omicron could replace Delta to become the dominant strain.

India’s Union Health Secretary Rajesh Bhushan asked the states to take necessary steps to control the spread of the virus.

Besides Jammu and Kashmir, Bhushan wrote to Odisha, Mizoram, Kerala, Tamil Nadu and Karnataka.

Jammu and Kashmir’s Kathua district recorded a 727% rise in infections within a week, according to The Print. The number of new cases rose from 49 on November 19 to 405 in November 25.

In Odisha, Dhenkanal, Kandhamal, Kendujhar, Nabarangpur, Balangir and Angul districts recorded a surge in coronavirus cases over the last week, Bhushan highlighted in the letter. In Dhenkanal, coronavirus cases rose from nine to 69 in a week – a 667% rise.

Eight out of 11 districts in Mizoram have been reporting a weekly positivity rate of over 10%, The Print reported.

In Kerala, Thiruvananthapuram, Kozhikode, Kottayam and Wayanad have reported over 10% weekly positivity rate, Bhushan said in the letter.

There has also been a rise in the number of deaths in the state. “Kerala has reported a slight increase in weekly new deaths to 2,118 deaths [week ending December 3] from 1,890 deaths [week ending November 26],” the official added.

In Tamil Nadu, Vellore district recorded a 31.63% rise in cases in the last week, Bhushan noted, according to The Print.

In Karnataka’s Tumakuru district, there was a 152% increase in coronavirus cases the last week – from 46 to 116.

Bengaluru also recorded an increase in deaths. “Increase in weekly new deaths has been noted in Bengaluru urban, from 8 new deaths reported in the week ending 25 November to 14 deaths in the week ending 2 December,” Bhushan said.

Karnataka is the state where the first two cases of the Omicron variant in India were identified. Gujarat and Maharashtra have also reported one case of the new strain each.

The Union health secretary said in his letter that in light of the emergence of Omicron, states have already been told to step up surveillance measures.

“In this context, required necessary steps to control the spread of infection and reduce fatality need to be taken as per the ongoing strategy of test-track-treat-vaccinate-Covid appropriate behaviour to keep the situation under control,” Bhushan added.