The Japanese government is considering shortening the current 14-day isolation period to 10 days for those identified as having been in close contact with a person infected with the Omicron COVID-19 variant, officials said Thursday.

The envisioned policy change, aimed at minimizing social disruption and preventing a strain on the medical system, comes as research suggests Omicron has a shorter incubation period than other variants of the virus.

But it could also fuel public concern about the recent alarming pace of rise in the number of daily coronavirus infections in the country, which reported over 18,000 new cases Thursday, well above Wednesday's tally of roughly 13,200.

"We have to devise ways to maintain social functions," Prime Minister Fumio Kishida told reporters in Tokyo. "We'd like to consider responding flexibly as needed."

The National Institute for Infectious Diseases has said a study of people infected with the Omicron variant in Okinawa Prefecture shows that the incubation period was around three days compared with about five for the other variants.

The Tokyo metropolitan government raised its COVID-19 alert to the second highest of four levels as the capital reported 3,124 infections Thursday, topping 3,000 for the first time since Sept. 2. It was last at that alert level in September.

The metropolitan government also projected that the seven-day rolling average of daily new COVID-19 cases will surge to 9,576 in a week if they continue to increase at the current pace.

People wearing masks for protection against the coronavirus walk in Osaka's Umeda area on Jan. 12, 2022.  (Kyodo)

In western Japan, Osaka Prefecture saw over 2,400 new COVID-19 cases Thursday, surpassing 2,000 for the first time since early September.

The health ministry says a person is a close contact if they have interacted with an infected person at a short distance or for an extended time, thus facing a relatively high risk of infection.

The current policy requires people identified as close contacts to isolate themselves for 14 days at home or designated facilities.

On Thursday, an advisory panel for the health ministry discussed the proposal to cut the isolation period to 10 days, and further to seven days depending on conditions of those identified as a close contact, officials said. The panel is expected to make a conclusion on Friday.

The Omicron variant, known to be highly transmissible, has been added to the list of coronavirus "variants of concern" by the World Health Organization, as it has the potential to evade immunity provided by vaccines.

But the risk of developing severe symptoms from Omicron is said to be likely lower than that for other variants. In the United States and Europe, where Omicron has spread rapidly, isolation periods have been shortened recently.

On Wednesday, the health ministry notified prefectural and local governments that doctors and nurses who have had close contact with people infected with COVID, including the Omicron variant, will be able to continue working if they test negative each day.

In the southern island prefecture of Okinawa, which has seen a spike in COVID-19 cases, medical services are affected by a staff shortage as many of their employees have been forced to miss work after coming into close contact with those who have contracted the virus.

Okinawa confirmed a record 1,817 cases Thursday, beating the previous high of 1,759 logged Saturday.

According to the government, about 16,000 medical facilities nationwide are involved in monitoring the health conditions of infected people recuperating at home, up 30 percent from late November.

Also on Thursday, economic revitalization minister Daishiro Yamagiwa requested that leaders of Japan's major business groups promote teleworking so companies can continue operations even if workers are infected with the virus.

"Teleworking is an effective means to continue operations. I want each entity to think out what plans can be utilized," Yamagiwa told the leaders in an online meeting.

Masakazu Tokura, the head of Japan's powerful business lobby Keidanren, said he would accept the request and called for shortening the isolation period for people who had close contact with the infected.

"There should be a system where people can swiftly return to society after they test negative," Tokura said.

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