21 March 2020

Severe Control Measures

From New York Times Interactive
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This map shows how many people the model estimates could get the virus in each county in the United States by two months from now.
One scenario — which is unlikely — simulates what could happen without any intervention. A second scenario envisions what would happen with some control measures, such as partial adherance to social distancing guidlines and a patchwork of government-imposed restrictions on work, travel, and dining out. A third envisions severe control measures: strict adherance across the country to social distancing, working remotely, closing schools and restaurants and banning large gatherings.
". . . The scenarios do not estimate what effect individual local actions will have on the outbreak. . . 
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The Columbia researchers’ model works by observing the behavior of the outbreak in the United States up until March 13, based on case records compiled by The New York Times, commuting patterns and other data.
The researchers use those observations to infer key features of the outbreak. One is how many people each infected person has tended to infect so far, about 2.2. Another is how many people may pass on the virus without knowing that they have it. The disease is spreading far too fast to be explained by known cases alone, and only about 1 in 11 infections have been reported, they found.
Those factors allow the researchers to simulate the spread of a virus in the future. They adjust those simulations under different scenarios in which the nation imposes a range of control measures to stop the spread.
The estimates are imperfect, but they are consistent with the available data. It is impossible to know the exact number of cases a week ago or to predict the future. It is also impossible to model the precise impact of unprecedented measures that America has already put in place to control the outbreak.
But the research estimates that if measures to slow the disease are not effective, the virus could sicken millions of people or more, losing steam on the coasts in May before spreading to the rest of the country over the summer.
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