The Japanese capital suffered more than 200 excess fatalities from pneumonia and other coronavirus symptoms early in the outbreak, dwarfing the period's officially recorded 16 from the new disease.

Even more deaths could have been undercounted in April, whose numbers will not come out until next month.

The National Institute of Infectious Diseases tracks fatalities from flu-like illnesses by collecting data from public health departments around the country. The tallies include those who died from pneumonia.

Excess fatalities are calculated by comparing these figures against baselines derived from past data.

The newest numbers show 50 to 60 excess deaths a week for the five weeks starting Feb. 17, adding up to hundreds more fatalities than usual.

Weekly excess deaths exceeding the margin of error come to 20 to 30. The NIID does not publish the raw numbers.

Excess deaths also occurred in the second half of 2019. Flu season had come early in Tokyo, peaking in December.

The influenza outbreak had subsided by the end of the year. But excess deaths reemerged in mid-February, suggesting a link to COVID-19.

The analysis for the past flu season is not finished yet, the NIID says, because the database records deaths through the late-March end of the season. A full picture cannot be pieced together until at least late May, the deadline for submitting data, according to the agency.

Japan's health ministry publishes total death counts as part of its monthly population survey.

But the deadline for prefectures to submit fatality figures is the fifth day of the second month after -- June 5 for April's numbers, for example. Japan's death counts are always two months behind as a result.

More COVID-19 fatalities may have been missed in April, with many of the dead never having been tested. Data on that month's deaths will not come out until late June.