NHK has learned that at least 122 people who contracted the coronavirus have died at home and other places across Japan after their conditions suddenly took a turn for the worse.
The National Police Agency says 56 of the deaths were reported in December, with 50 of those having died while in quarantine at home or accommodations for people with mild symptoms.
The agency also says that in some cases, people fell ill but could not receive medical treatment in time, and their infection was confirmed after they died.
The Japanese Association for Infectious Diseases President Tateda Kazuhiro says patients who appear to have only minor symptoms could suddenly become seriously ill.
He calls for a framework to check on infected people regularly, and send them to medical institutions for treatment if their conditions suddenly change.