Prime Minister Yoshihide Suga on Friday warned of signs of a resurgent spread of the novel coronavirus as colder weather drives more people indoors.
"We have to watch the situation with a stronger sense of caution than before," Suga said in a Diet committee session, a day after new daily infections nationwide topped 1,000 for the first time since August.
While most of those cases continued to come from urban centers such as Tokyo and Osaka, there have also been clusters of infections in Hokkaido as well as northeastern parts of the country including Miyagi and Fukushima.
Experts say this could be due to more people spending time in poorly ventilated rooms as temperatures turn lower.
Japan reported 1,050 new cases of infection with the COVID-19 virus Thursday, exceeding 1,000 in a day for the first time since Aug. 21, according to a Kyodo News tally based on official data.
The uptick came after the government eased restrictions and promoted travel within the nation aiming to support the economy, which has been hit hard by the pandemic.
In addition to Tokyo and Osaka, 119 new cases were reported in Hokkaido, a popular tourist destination, in its highest single-day increase. The data marked the first time the island has seen a daily figure above 100 since the outbreak of the virus.
Some clusters of infections were reported in the district of Susukino, in Sapporo, which is a major nightlife and entertainment hub in Hokkaido.
Atsuo Hamada, a professor at Tokyo Medical University, said the increase in cases in Hokkaido and the Tohoku region were possibly due to the cold weather, which is also believed to be a likely cause of the recent surge in patients in Europe.
"We need to be vigilant," he said.
Tokyo confirmed 269 new infections Thursday, bringing its cumulative total to 31,893 — the highest by far among the nation's 47 prefectures. The new tally comes after 7,354 virus tests were conducted on Monday, the highest single-day figure for the capital so far.
Of the 269 newly infected, 154 contracted the virus via unknown routes, the metropolitan government said.
Osaka Prefecture, which has the second-highest cumulative total, confirmed an additional 125 cases. The daily increase in the prefecture has often surpassed 100 since late October. Earlier in the month the figure had remained around 50.
"While I cannot say whether this is a third wave (of the virus), it is true that there is a rise" in the number of cases, said Osaka Gov. Hirofumi Yoshimura, adding he would hold a conference with a panel of experts possibly next week.
The additional 1,050 infections confirmed Thursday brought the nationwide tally to 105,688 cases including around 700 from the Diamond Princess, a cruise ship that was quarantined in Yokohama in February. The death toll now stands at 1,821.
"Effectively the third wave has arrived," said Aichi Gov. Hideaki Omura, referring to the increase in infections in his prefecture over the past week.
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