Bowing to pressure from the central government and media, the Tokyo Metropolitan Government has unexpectedly released a stockpile of data on the number of coronavirus tests conducted and the infection rate dating back to late January.

Disjointed data on testing, not just in Tokyo but throughout Japan, has been the subject of controversy and scrutiny for months. Researchers say it’s impossible to understand the true severity of the pandemic without this information.

While testing remains comparatively low in Japan, the capital’s decision to release this information — and voice its intention to do so every day — marks a significant shift in its policy on information disclosure.

On Friday, officials at City Hall provided reporters with long-awaited figures dating back to Jan. 24, including total tests conducted, number of individuals tested, daily infection counts and the average infection rate as calculated over seven days.

While the data mostly corroborates what has already been released publicly, officials hope it will shed light on matters that have been causing confusion since the pandemic began.

Tokyo began to rely heavily on private testing sites in early April, when new cases in the capital began to hit a fever pitch. On several days, PCR tests at these sites accounted for more than two-thirds of all tests conducted in the city.

It was from late March through mid-April that the average infection rate began to take off, peaking at 31.6 percent on April 14. That had dropped to 7.5 percent as of Thursday.

Most experts agree that an infection rate of 10 percent for the novel coronavirus indicates that an adequate number of tests is being conducted.

Tokyo Gov. Yuriko Koike said the city has the capacity to conduct 3,000 tests a day, but is only conducting about 1,000, and on some days up to 2,000.

City officials warned against comparing the data released Friday with figures already published on the city’s website. Friday’s data include the number of individuals tested, they said, while the figures online detail the number of tests conducted.

Comparing those two sets could cause confusion since almost all COVID-19 patients were tested multiple times. Government policy requires patients to test negative twice before being discharged. In some cases, individuals have tested positive after testing negative.

Up until Friday’s announcement, tracking the number of polymerase chain reaction tests in Tokyo was nearly impossible because public hospitals and medical facilities were reporting the figure daily while private facilities were doing so only once a week.

On a few different occasions, the PCR numbers already reported by the metropolitan government were later revised, giving the impression the city was inflating the numbers to silence critics.

Some experts say the best number to gauge the spread of the contagion is the effective reproductive rate, dubbed R. In short, the virus is still spreading if R is above 1 and subsiding if below.

Earlier this month, the central government announced that, as of May 1, the R for both Japan and Tokyo had fallen below 1.

In a time of both misinformation and too much information, quality journalism is more crucial than ever.
By subscribing, you can help us get the story right.