The Economist July 25th 2020 pp19 United States | Easing lockdowns and covid-19 “The geometry of the pandemic”
Virus spread is geometric. If your rate after lockdown is driven to 3 then as life resumes residual spread of the virus will proceed 3, 6, 12, 24 etc. but if your rate after lockdown is 384 then residual spread of the virus will proceed 384, 768, 1,536, 3072 etc. This reality helps explain the rise in COVID-19 in various American states.
Cases of COVID-19 in America peaked in April at 100 per million and then fell slowly to about 60 per million in early June but then rose geometrically to nearly 200 per million today. By contrast, cases peaked to about 60 per million early in April in France then fell to a low of <10 per million and been sustained since early May. While both countries and various regions have re-opened after lockdown the outcomes are very different. How do we account for this disparity?
One big factor, not widely understood, is that “the spread of a virus: [has a] geometric progression, such as 1,2,4,8,16” so the volume of spread depends much on the rate of disease when the regions re-opened. So contrast 16, 32, 64, 128, 256. France re-opened at 13 per million, Texas 44 per million and Georgia 95 per million. Models based on baseline data have been remarkedly accurate in predicting future case levels. Americans are paying the price for not achieving complete reversal before re-opening from full lockdown. “The implication of these figures is that when the virus is widespread, even small amounts of activity can make infections soar.”
What to do? Without additional medical interventions like vaccines or better treatments, stopping the spread, at this point, would require a repeated full lockdown. “At the moment few politicians seem prepared for such a thing.”
As we have come to understand throughout the country, there’s also a inequality in COVID-19 “It’s predominantly in low-income metro areas. Hispanic communities are being devastated. And there’s no political leadership dealing with it.” Says Perter Hotez, of Texas Children’s Hospital in Houston, Texas.
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