Using cell phones to track movement.
Tracking the way in which humans moved before and during the pandemic has been a very innovative way in which epidemiologists have been able to describe (and predict) COVID19 spread. Specifically, many scientists are using cell phone data to track movement.
Yesterday, the Lancet (a highly reputable scientific journal) published a study in which they wanted to answer… HOW strong IS the relationship (i.e. correlation) between movement and COVID19 spread. Spoiler: VERY strong.
We can see this visually too. For example, as of today, there are 14 hot spot states. These states have very similar patterns in movement to non-essential businesses (Figures). The blue line indicates change in movement to non-essential buisnesses. For example…
In Texas, at the peak of the stay-at-home orders (April 8), there was a 70% reduction in movement to non-essential places. In other words, people moved 70% less to non-essential buissness than before the pandemic. Which was great; it worked to curve spread. However, since then, people have been moving more and more to non-essential businesses. In mid-June, Texans only moved 15% less than before the pandemic. This means they were almost back to “normal”. This was followed by exponential increase in COVID19 cases.
We see the same with AZ, FL, and CA (although CA is not as dramatic).
As a comparison, I also included NY. Movement to non-essential businesses stayed constant for almost 2 months, then once cases were down, SLOWLY started to increase. The highest NY has gone is 55% reduction in movement. They haven’t even gotten close to the 15% reduction like we see in Texas.
Translation: Your movement to non-essential places MATTERS! We can all reduce our movement to keep this pandemic under control.
Love, your local epidemiologist
Lancet study: https://www.thelancet.com/…/PIIS1473-3099(20)3055…/fulltext…
Mobility data and graphs: From UnaCast. A really fun site to play around with: https://www.unacast.com/covid…/social-distancing-scoreboard…