Tokyo's voluntary standstill may have stopped COVID-19 in its tracks


Date:
November 5, 2020
Source:
Institute of Industrial Science, The University of Tokyo
Summary:
Research shows that Japan's noncompulsory state of emergency
generally succeeded in reducing human movement. A recent study
used mobile phone location data for January-April 2020 to record
and plot movement of people in metro Tokyo during the emergence
and first wave of COVID-19.

Researchers found a movement reduction of over 50 percent, which
in turn limited social contact and slowed infection spread.



FULL STORY ==========================================================================
Why did Japan largely contain COVID-19 despite famously jam-packed
Tokyo and despite the country's proximity to China? With no penalties
and only requests for cooperation, Japan's state of emergency somehow
averted the large-scale outbreaks seen elsewhere. At least one viable
answer has now emerged.


==========================================================================
A new comparative analysis of people's mobility during the virus' first
wave illustrates how drastically the Tokyo masses slowed. That slowdown
may have throttled the spread of infections.

In a study from The University of Tokyo Institute of Industrial Science, researchers examined location data from more than 200,000 mobile phone
users.

Using these data, the researchers calculated the human movement in Tokyo
before and during the state of emergency. The striking findings were
published in Scientific Reports.

"Using anonymized data that represented about 2% of the population, we
could compute human movement and contact rates at a 100-meter grid-cell
scale," study first author Takahiro Yabe says. "We found that 1 week into
the state of emergency, human mobility reduced by 50%, which led to a 70%
drop in social contacts." Less contact implies less disease spread.

Japan declared its state of emergency on April 7, followed by a gradual
series of requests to close businesses and work from home, along with aggressive travel entry restrictions. However, under Japanese law,
a mandatory lockdown could not be implemented or enforced.

The data spanned from January to April. A look at the major hub train
stations around central Tokyo, including Shinjuku Station, the world's
busiest, finds April 14 in Tokyo had 76%-87% fewer visits compared with pre-crisis January.

The researchers also analyzed how much and how far people in greater
Tokyo traveled, with both showing around a 50% reduction. In other
words, people moved less and stayed nearer to home. Social contact
could also be computed based on people's spatial proximity. That,
too, was substantially reduced, nearly to the 80% reduction level the government had targeted. The decline trends generally corresponded with governmental requests for people to do remote work, for school closures,
and the actual state of emergency.

Going a step further, the study paired socioeconomic data with the
mobility results. This showed those with higher income were more capable
of reducing social contact and, consequently, lower the chance of
COVID-19 transmission.

Finally, the study put the mobility data against the estimated effective reproduction number, a key statistic estimating how many cases one
infection can cause. This validated how the reduced contact also was
likely to reduce infections.

"With a noncompulsory and nonpharmaceutical intervention, Tokyo had to
rely on citizens' cooperation. Our study shows they cooperated by limiting their movement and contact, subsequently limiting infections," study
co-author Yoshihide Sekimoto explains. "These findings offer insights that policymakers can apply when estimating necessary movement restrictions."
Amid the complex human and environmental dynamics behind fighting the
spread of COVID-19, there is now stronger evidence that staying home
and maintaining distance really work.


========================================================================== Story Source: Materials provided by Institute_of_Industrial_Science,_The_University_of_Tokyo.

Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. Takahiro Yabe, Kota Tsubouchi, Naoya Fujiwara, Takayuki Wada,
Yoshihide
Sekimoto, Satish V. Ukkusuri. Non-compulsory measures
sufficiently reduced human mobility in Tokyo during the
COVID-19 epidemic. Scientific Reports, 2020; 10 (1) DOI:
10.1038/s41598-020-75033-5 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/11/201105112950.htm

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