The greater Tokyo metropolitan area is the last region awaiting the end of Japan’s second state of emergency, but there are strong indications that a number of COVID-19 infections have gone undetected and the pandemic isn’t subsiding as quickly as public data would suggest.

Daily infections have seen a downward trend nationwide since early January. However, low testing, miscounts to the tune of hundreds of cases, the absence in publicly released figures of tests conducted by private companies and efforts to scale back contact tracing hint at the possibility that an unknown number of cases have gone unreported due to strained resources, bureaucratic missteps and temporary policy changes.

No single fact or figure can perfectly represent the scope and severity of the outbreak, but collectively they can provide benchmarks for public officials to reference in deciding whether to tighten or loosen virus countermeasures. If the numbers are incomplete, however, the decision will likely be affected by that.

COVID-19 testing

Since January, when a state of emergency was declared in Tokyo, Kanagawa, Chiba and Saitama prefectures, COVID-19 tests conducted nationwide have been declining steadily.

On Jan. 13, the country conducted more than 81,255 polymerase chain reaction (PCR) tests according to the health ministry. That number declined to less than 20,000 tests, or less than a quarter, on Feb. 28.

“It should be the opposite,” said Kenji Shibuya, director of the Institute of Public Health at King’s College London.

Japan has always prioritized contact tracing and cluster chasing over expansive testing, a policy that has consistently drawn criticism from experts who say more testing is necessary to accurately measure where the virus has spread or continues to do so.

The country is testing marginally more than other countries in East and Southeast Asia but it still falls far short when compared to the West.

Japan had in total conducted just over 61 tests for every 1,000 people as of Sunday, according to Our World In Data. In comparison, more than 500 tests had been conducted for every 1,000 residents by late February in Italy, Australia and Germany. South Korea had administered just over 128 tests for every 1,000 residents as of Monday, while the United States had conducted more than 1,000 tests for every 1,000 individuals amid the worst of the pandemic.

Japan should be testing more people to prevent a rebound after the emergency is lifted, Shibuya said.


In Japan, disjointed data aggregation and the use of fax machines often hinders the reporting of test results.

On Feb. 15, the Tokyo Metropolitan Government revealed that 838 cases had gone unreported.

Most of the cases involved people thought to have become infected during the year-end holiday, officials said, but weren’t initially reflected in public data because workers at testing centers had failed to press a button to confirm each case and report it to the health ministry’s database.

The errors occurred at 18 test centers over a period of more than two months beginning in mid-November.

Private company testing

Around the same time, a growing number of private companies began offering cheap, quick and easily accessible PCR testing to the public.

Private companies have no obligation to report test results to local governments, so those figures aren’t reflected in publicly released data. Tokyo officials said the number of companies providing tests — and the number of people purchasing them — has been increasing since early January, but it’s difficult to know how many there now are.

People walk the streets of Yanaka Ginza, a popular shopping corridor in Tokyo's Taito Ward, on Sunday. | RYUSEI TAKAHASHI
People walk the streets of Yanaka Ginza, a popular shopping corridor in Tokyo’s Taito Ward, on Sunday. | RYUSEI TAKAHASHI

Contact tracing

Contact tracing allows public officials to track the virus by retracing the recent activity of those who have tested positive for COVID-19.

But due to a shortage of staff, on Jan. 22 the capital said it had asked test centers to divert resources away from contact tracing efforts and towards hospitals and medical facilities being stretched by the sustained influx of coronavirus patients.

Neglecting efforts to trace new cases could conceal the trajectory of asymptomatic infections and render the city blind to the whereabouts of the virus.

If that were the case, the percentage of untraced and asymptomatic cases would have risen as a direct result of the policy change.

“Looking at the data, that’s just not the case,” said Norio Omagari, director of the Disease Control and Prevention Center and an advisor to the Tokyo Metropolitan Government, during a meeting in mid-February.

The reason for the absence of that increase touches upon a larger problem.

Japan’s policy on cluster tracing was limited in scope long before the brief policy change in January, and an expansive approach could have provided a more reliable grasp of the situation.

Tokyo officials conceded in late February that it’s likely those figures on untraced and asymptomatic cases didn’t change because test centers had already been focusing what little resources they had on tracing the elderly, vulnerable or hospitalized.

On Friday, Tokyo Gov. Yuriko Koike announced she had asked test centers to reverse the decision and focus their attention once again on contact tracing.

Kanagawa Prefecture had made a similar request last month to reduce contact tracing efforts, and last week it announced it would reverse that decision in preparation for a fourth wave as the four remaining areas approach the end of the country’s state of emergency.

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