A Japanese research group estimates that Tokyo's number of new daily coronavirus cases will rise gradually through late August.

The group from the Nagoya Institute of Technology led by Professor Hirata Akimasa used artificial intelligence to estimate what the figures would be after Japan downgrades its legal classification of COVID-19. From May 8, part of the medical fee for a coronavirus test and treatment, which are now free, will be borne by patients.

The researchers assumed that more transmissible variants will not emerge, and peoples' movements will return to pre-pandemic levels around summer.

AI was used to analyze data including the numbers of people who have been infected by Monday and the numbers of social network postings with words indicating lively social activities, such as drink party and barbecue.

The group said the AI estimated that the daily average of new cases for a seven-day period in mid-May will be about 3,100 in Tokyo. It said that the figure stayed the same regardless of the percentage of people who wear masks.

But for late August, the AI estimated that new cases will be 6,900 with 20 percent of people wearing masks, 5,400 if half the people in the capital wear masks, and 4,100 with almost everyone wearing a mask.

Tokyo's seven-day average of new infections as of Monday was 1,326.

Hirata said most people appear to be gradually easing anti-infection measures. He said he hopes people will continue to take appropriate measures in some cases, such as meeting seniors, even after the legal classification of COVID-19 is downgraded.