Japan's new flu cases hit record high in late December

The number of influenza patients reported at designated medical institutions across Japan at the end of the year hit the highest level since comparable data became available in 1999, the Japanese government said Friday.

Across roughly 5,000 institutions, 317,812 patients had been reported in the week through Dec 29, averaging 64.39 people per facility and surpassing the warning level of 30, according to the Ministry of Health, Labor and Welfare.

It marked the 10th consecutive week of increase and a 1.51-fold rise from the week prior, and there were shortages of some of the medications used to treat influenza.

"The fact that people expanded their range of movement as they entered the holidays could be a contributing factor," a ministry official said.

Major drug makers Sawai Pharmaceutical Co and Chugai Pharmaceutical Co announced they will temporarily halt the supply of the flu medicine Tamiflu and its generic version due to production struggles in meeting soaring demand.

Sawai said it plans to resume supplying the generic drug in late January or early February, while Chugai announced it will suspend part of its supplies until late February.

"People have a weakened immune system as there hadn't been an influenza outbreak for a while" due to measures to contain the COVID-19 pandemic, said Hiroyuki Kunishima, professor at St Marianna University School of Medicine, adding that the surge was putting a strain on hospitals.

"Getting a flu shot even at this stage will be effective" as there is a possibility that different strains from abroad may spread, Kunishima said.

Patients increased in all 47 prefectures, with Oita Prefecture in southwestern Japan recording the most, averaging 104.84 people per facility. The lowest was Okinawa Prefecture, southern Japan, averaging 24.3 people per facility.