英語で: This graph has Tokyo’s authorities worried:

(Source)

A total of 259 people infected seems like little cause for concern, especially in a metropolis of millions. However, as it has in other countries, that number does not entirely reflect the seriousness of the situation.

First of all, the number of infections in an area could double every three days (or even faster).

Second, this disease has an incubation period of around five days. Together with recommendations from health authorities in Japan to contact them after two to four days of symptoms, this means that most of the 259 people with Covid-19 were infected over a week ago.

Combine doubling with incubation and we have our first bit of bad news; the number of infections at this moment could well be over one thousand.

For the second bit of bad news, let us take the back of an envelope to check where doubling will take the numbers in one month:

Over one million infections. Reported mortality rates for Covid-19 are between 0.4% and 8.3%, so:

Tokyo risks between 4000 and 83000 deaths if no measures are taken well within one month.

Every three days delay on top of that would double those estimates.

And that is with the rather optimistic assumption that every infection from a week ago got caught by the tests.

Japanese: この統計は東京の大多数の人が関心を持っています。

（参照）

東京が２５０人病気であんまり問題ないようです、でもそうではない。

毎三日、ウイルスの量は倍に出来ます、そして今のテスト済み人は先々週感染した。だから、今東京は多分１０００人病気であります。

そのあと、来月の計算が：

百万人ぐらいなります。Covid-19の死亡率は0.4%-8.3%：

何もしなければ4000〜83000人が死亡する可能性があります。