Photo/Illutration Pedestrians on the streets of Tokyo's Shinbashi district on May 28 (Naoko Kawamura)

An analysis of pedestrian traffic in Tokyo suggests another uptick in COVID-19 cases may be just around the corner.

The study by The Asahi Shimbun was based on the flow of human traffic aggregated by Tokyo-based Agoop Corp., a Softbank Group subsidiary that tracks people’s movements through GPS data on their mobile phones.

The Asahi used data from Agoop compiled between April 1, 2020, and May 25, 2021, to calculate the average population per week around 14 rail hubs in the capital.

Accepted wisdom to date suggests that if fewer people are on the streets, fresh cases of COVID-19 will show signs of dropping about two weeks later.

One finding for the one-week period from April 28, following the declaration three days earlier of a third state of emergency, was that the flow of pedestrian traffic had fallen to 64 percent of the level of the previous week. The number of new COVID-19 cases for the week from May 12 was 90 percent of the level for the week from April 28, while the figure dropped to 73 percent for the week from May 19.

However, the Agoop data points to a subsequent increase in the number of people going out.

In comparison with the previous week, pedestrian traffic for the week from May 5 increased by 24 percent, while it had increased by 15 percent for the week from May 12. The figure remained unchanged for the week from May 19.

While the number of new COVID-19 cases has been falling since the week from April 28, the latest figures indicate another uptick may be possible soon.

“A key lesson we've learned so far is the need to maintain restraints on people's movement during the period when new infection cases start to decline so as to further reduce new cases,” noted Koji Wada, a professor of public health at the Otawara, Tochigi Prefecture-based International University of Health and Welfare. “But gaining the understanding of the public will not be possible unless data is presented about the number of vaccinations given and an exit strategy is also clearly presented.”

A comparison of total human traffic flow for four-week periods found a 78-percent reduction between April 28 and May 25 compared with the immediate preceding four-week period between March 31 and April 27.

But in comparison to the four-week period between April 29, 2020, and May 26, 2020, when the first state of emergency was declared, the figure for April 28 and May 25 represented a 64-percent increase. The figure indicates that the effects of the third state of emergency will likely be weaker than for the first one.