Japanese officials expressed alarm on Thursday as Tokyo, the host city of the, reported a record number of new cases for the third day in a row.
"We have never experienced the expansion of the infections of this magnitude," Chief Cabinet Secretary Katsunobu Kato said, according to The Associated Press.
Tokyo reported 3,865 new cases on Thursday. Katsunobu said cases were rising around the rest of the country as well, with over 9,500 new cases registered nationally.
While Japan has so far avoided the kind of massive outbreak seen in some other countries, its seven-day rolling case average is rising.
"While almost nothing is helping to slow the infections, there are many factors that can accelerate them," Dr. Shigeru Omi, a government medical adviser, said, referring to the ongoing Olympic Games and summer vacation.
"The biggest risk is the lack of a sense of crisis, and without it the infections will further expand and put medical systems under severe strain," he said, according to the AP.
Japan's Prime Minister Yoshihide Suga said his government would decide on Friday whether to expand emergency measures, which have been in place in Tokyo since July 12.
Taro Kono, Japan's vaccine minister, told The Associated Press that most of the recent cases are in people 30 years old or younger.
"I would like young people to be aware that the Delta strain is a very tough, dangerous enemy," she said.
The director of Japan's Disease Control and Prevention Center, Dr. Norio Ohmagari, said Tokyo's surge is, "heading toward an explosive expansion we have never experienced before," the AP reported.