Professor simulates virus spread in Tokyo

A Japanese professor warns that even if stringent anti-coronavirus measures similar to those last spring are taken, it will take until the end of February to significantly reduce the number of new infections in Tokyo.

Professor Nishiura Hiroshi of Kyoto University offered the prediction after making a simulation of the future virus spread in Tokyo. The government plans to declare a state of emergency in the capital area.

In his mathematical modeling, the professor used replication rates that indicate the average number of people a single coronavirus carrier will infect.

Nishiura says that the current, estimated replication rate in Tokyo is 1.1. He says that with no new measures, the daily figure for new infection cases will rise to about 3,500 by the end of February, and to 7,000 by the end of March.

He notes it is possible to reduce the rate to 0.99 by taking measures, including shorter business hours for restaurants. He says the rate means that new daily cases will remain almost the same as now, at around 1,300 at the end of February.

Nishiura reasons that if the rate could be reduced to 0.72, new daily cases would fall under 100 by February 25.

He says a 35 percent reduction would require the level of anti-virus measures imposed during a state of emergency declared last spring.

Nishiura adds that if a second state of emergency fails to achieve similar results, reducing the number of infections will take longer.