India on January 5 reported its first death linked to the Omicron coronavirus variant in Rajasthan as new COVID-19 cases crossed 70,000 in what the Centre said was an "exponential rise" with the acceleration "steeper than ever" reflected by a higher R naught value than during the peak of the brutal second wave.

As Tamil Nadu and Himachal Pradesh joined a growing list of states to clamp night curfew in line with fresh curbs to deal with the expanding pandemic, the Centre said the upsurge in COVID cases--a 6.3 times rise in the last eight days--is happening in cities and the Omicron variant is the predominant circulating strain.

"The R naught value is 2.69. This is higher than 1.69 that we saw at the second wave on peak. The acceleration of cases is steeper than ever," NITI Aayog member (Health) Dr V K Paul told a joint news conference. A ferocious second COVID wave had swept the country in April-May last year. A total of 2,135 cases of the Omicron variant have been detected across 24 states and UTs out of which, 828 have recovered or migrated, according to the Union Health Ministry data updated at 8 am.

Maharashtra recorded the maximum number of 653 followed by Delhi at 464, Kerala 185, Rajasthan 174, Gujarat 154 and Tamil Nadu 121 Omicron cases. Officials in the Union health ministry said samples of a 73-year-old man in Rajasthan's Udaipur, who died last week, showed the presence of the Omicron variant.

The case of death in Rajasthan is technically Omicron-related, Joint Secretary in Health Ministry told the press conference. "That person had already died by the time the Omicron positive results came. He was an elderly person and had diabetes and comorbid conditions and was being treated as per protocol for his co-morbid conditions and for the infection. Our guidelines state that if a coronavirus positive patient dies, it is considered as COVID-19 fatality. Similarly, if a person is found to be Omicron positive, even if it detected late, we will consider that as Omicron positive case only," the joint secretary said.

The man, who was found infected with Omicron in genome sequencing and who had tested negative for the infection twice, died in a Udaipur hospital on December 31, state government officials had said. Several states also reported more doctors testing positive for COVID raising fears of shortage of medical personnel to deal with any crisis.

Nearly 160 resident doctors of hospitals in Mumbai run by the Maharashtra government and the local civic corporation have tested positive for coronavirus in the last three days, a senior office-bearer of their association said. India recorded a single-day rise of 58,097 new coronavirus infections, the highest in around 199 days, taking the total tally of cases to 3,50,18,358, according to the Health Ministry data which also showed that the active cases were above 2 lakh after around 81 days. A total of 58,419 new infections were reported on June 20 last year.

The countrywide COVID tally crossed the 70,000 mark if the data released by some state authorities in the evening is also taken into account. Maharashtra, West Bengal, Karnataka and Delhi were among the states which recorded a huge single-day jump in the cases.

The Indian Council of Medical Research (ICMR) Director General Dr Balram Bhargava said the spike in the number of COVID cases is being witnessed in cities and "the Omicron variant is the predominant circulating strain". Mass gatherings need to be avoided to lower the speed of the infection spread, he told the news conference, in the backdrop of the upcoming Assembly polls in five states which is expected to witness campaign rallies. "We are now facing an exponential rise in (the number of) COVID-19 cases and we believe that largely, it is being driven by Omicron, particularly so in the western parts of our country and even particularly so in larger cities from where we have more data," Dr Paul said.

On December 30, the case positivity rate was 1.1 per cent and the next day, it was 1.3 per cent and now, the country is reporting a positivity rate of five per cent, he said, adding that similarly, there were 13,000 COVID cases on December 30 and the number went up to 58,000 on January 4.

He, however, added that the hospitalisation rates are relatively low. It is close to 3.7 per cent in Delhi and five per cent in Mumbai. "That is the early input we have. Compared to this, last year and even in 2020, the hospitalisation rate was close to 20 per cent," Paul said. He said though there is no need to panic, people must be alert, disciplined and prepared, adding that the country will face this phase of the pandemic as well.

On whether India is witnessing a third COVID wave, Paul said in other countries it has been seen that just like a steep rise, there was also a steep decline in the number of cases. "In Denmark, the UK and South Africa, cases started declining within a month or a month and a half. We cannot say this clearly for our population. How it behaves will depend on past infections, the vaccination status and our own characteristics and population density. It cannot be extrapolated that just like the cases behaved there within a month, it will happen here also.

"Saying it at this stage that it will go on till which point and for how long will be premature. If any scientific data comes, we will share. I would not venture into that except to say that like the previous waves, different parts of our nation will be in different stages. It starts in some states and then goes on and on. We are watching the dynamics of the pandemic carefully," the NITI Aayog member added.

The joint secretary said there has been a surge in the number of COVID cases globally, adding that 25.2 lakh cases of the infection were recorded all over the world on January 4, "the highest ever since the onset of the pandemic". "India has reported an increase of more than 6.3 times in the number of cases in the last eight days and a sharp increase in the case positivity rate from 0.79 per cent on December 29 to 5.03 per cent on January 5," he said.

He said six states -- Maharashtra, West Bengal, Kerala, Delhi, Karnataka, Tamil Nadu -- have over 10,000 active Covid cases each. He further stated that Maharashtra, West Bengal, Delhi, Kerala, Tamil Nadu, Karnataka, Jharkhand and Gujarat are emerging as the states of concern.

Also, 28 districts in the country are reporting a weekly COVID positivity rate of more than 10 per cent, while 43 districts are reporting a weekly positivity rate between five per cent and 10 per cent, the joint secretary said. The country's COVID death toll has climbed to 4,82,551 with 534 daily fatalities, the Health Ministry data showed.

The active cases have increased to 2,14,004, comprising 0.61 per cent of the total infections, while the national COVID-19 recovery rate was recorded at 98.01 per cent, the health ministry said. An increase of 42,174 cases has been recorded in the active COVID-19 caseload in a span of 24 hours.