A 37-year-old man who arrived in Delhi from Tanzania has tested positive for Omicron, making it the first case of the new COVID-19 variant in the national capital and the fifth in the country.

The patient, currently admitted to the Lok Nayak Jai Prakash (LNJP) Hospital, has mild symptoms, hospital officials said.

"So far, 17 COVID-19 patients and six of their contacts have been admitted to the Lok Nayak Hospital. The Omicron variant has been found in one of the 12 samples sent for genome sequencing so far, according to a preliminary report," Delhi's Health Minister Satyendar Jain said.

"The patient is an Indian and had returned from Tanzania. He was admitted to the hospital on December 2 with mild symptoms sore throat, fever and body ache," Medical Director Suresh Kumar said.

"The patient's travel history is being collated and his contacts are being traced," he said.

The Delhi health minister said banning international flights is the most effective way to contain the spread of the Omicron variant.

It is being reported that the gestational period in case of Omicron could be more than other variants. This means an infected person may go undetected at the airport All the cases have come from affected foreign countries. The central government should take it seriously, he said.

Jain said that there is a 99 percent chance that the mask can save people from all COVID-19 variants, be it Alpha, Beta, Delta or Omicron .

Experts have been saying that the third wave of COVID-19 can hit the country in January-February. It can be prevented if everybody wears a mask, he said.

The minister said more than 90 percent of the eligible population has got the first dose of the COVID-19 vaccine. Sixty percent of the people have got the second dose. We appeal to the remaining people to get vaccinated as soon as possible, he said.

Jain said more than one lakh people are being vaccinated against COVID-19 in Delhi every day. If we continue at the same speed, everyone will be covered soon.

He pointed out that many people have not received their second dose of Covishield yet due to the large gap (84 days) between the doses.

In response to a question on a booster dose, the minister said the city government will follow the notification of the central government and the recommendations of experts.

The country reported the first two cases of the Omicron variant of COVID-19 on Thursday in Karnataka -- a 66-year-old South African flyer and a 46-year-old Bengaluru doctor with no travel history. Both men are fully vaccinated.

On Saturday, a 72-year-old NRI man from Gujarat and a 33-year-old man from Maharashtra tested positive for the new strain.

All COVID-positive international travellers are being admitted to the LNJP Hospital, where a dedicated ward has been set up for isolating and treating them.

According to the Centre, the countries designated as "at-risk" are European countries, including the UK, and South Africa, Brazil, Botswana, China, Mauritius, New Zealand, Zimbabwe, Singapore, Hong Kong and Israel.

Under the new norms, RT-PCR tests are mandatory for passengers arriving from the "at-risk" countries and they will be allowed to leave the airport only after the results come.

Also, two percent of the passengers arriving on flights from other countries will be subjected to the test randomly.