Photo/Illutration Many commuters in Osaka wear face masks on the morning of April 8. (Tatsuo Kanai)

The recent spike in new coronavirus infections in Tokyo and Osaka and Fukuoka prefectures prompted their inclusion on Prime Minister Shinzo Abe’s state of emergency declaration over other areas with high infections, the chair of the government's expert panel on the health crisis said April 7.

Kanagawa, Saitama and Chiba prefectures made the cut due to the high volume of people traveling daily to and from Tokyo for business and other reasons.

Hyogo Prefecture was chosen due to its proximity to densely populated Osaka.

Shigeru Omi, who is also president of the Japan Community Healthcare Organization, took questions from media representatives at a news conference after Abe announced the declaration.

Omi said the panel presented the government with three main indicators in calling for a state of emergency.

These were: the cumulative number of coronavirus infection cases; the number of days needed to double the number of infections; and the ratio of cases for which the infection route was unknown, which the panel analyzed over a two-week period, Omi said.

As of April 6, Tokyo had 1,123 infections, while Osaka had 429, the health ministry said.

In early March it took 10 days for Tokyo's cases to double, but recently it took only five and Osaka's cases recently doubled in just short of seven days, Omi said, adding that the shortening of the period raises the likelihood that a sharp increase in new cases will occur in the near future.

The cumulative number of cases in prefectures neighboring Tokyo and Osaka, namely, Saitama, Chiba, Kanagawa and Hyogo, also exceeded 200.

Fukuoka, with 199 infections, has not seen a large cumulative number of cases, but infections doubled in under three days as of April 6, leading to its inclusion on the list, Omi said.

He said 72 percent of the infections were isolated cases, rather than cluster infections that have caused surges of cases in other prefectures.

Infections in the northernmost main island of Hokkaido and 39 prefectures had not reached the stage as of April 6 where they warranted inclusion in the state of emergency, Omi said, but he acknowledged that infections could still spread in the areas.

Aichi Prefecture has 260 confirmed cases, topping Fukuoka Prefecture, but Abe did not include it in the state of emergency declaration.

“While Aichi certainly does have a large number of cases, the pace at which those cases double is a gradual one," said Yasutoshi Nishimura, the state minister for economic revitalization who is also in charge of the special measures law to deal with the coronavirus.

"There is also a comparatively low number of cases for which the infection route is unknown,” he added, speaking at the April 7 Upper House Rules and Administration Committee session.

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