Covid-19 County -level predictions for the US

The CARSI (Center for Advanced Research of Spatial Information) Model uses an embedded recursive SIR (susceptible, infected, removed) model to simultaneously solve for two key epidemiological parameters Ro and the contact ratio (CR). The modeling is based on a set of assumptions including a fatality rate of 0.6 %, an initial infection rate of 0.00125 and a cycle duration of 21 days. It is modeled on fatalities as reported by the New York Times. The model assumes 42 million vaccinations have occurred in the US by February 8, 2021 and will increases as a sigmoidal function to an asuymtote of around 190 million. The IFR is reduced as a function of the age class and fatality rate of that class as derived from CDC data. The three categories used are 65+, 18-64 and 0-17. The first set of vaccines (1a) are to be given to medical workers (~20 million) assumed to be in the 18-64 group and Long Term Health Care facilities (~3 million) in the 65+ category, followed by (1b) front line workers (~30 million) in the 18-64 bucket and those 65+ (51 million), then distributed among the 18-64 and 0-17 age groups for the balance. This was the most parsimonious choice given the varied and shifting state-wide approaches. Each county was assumed to get a pro-rate share of vaccines based on population. Population source was the 2020 US Census estimates. The total projections from the model are calculated by summing up the results from over 3,200 county level models. To see the model for an individual county, click on a county on either map to the right.

Key findings: Given these assumptions the projected fatality rate for September 15, 2021 is 631,000. Without the attenuating effect of the vaccine the rate was projected to have been 748,605 by May 1, 2021. In essence, almost 190,000 lives were saved due to the introduction of the vaccine as projected by the model out to May 1, 2021. The model projection was made with data from February 21, 2021. The only thing updated was the vaccination model.

Modeling: Sean C. Ahearn, Professor & Director,
Web-mapping: Shipeng Sun, Assistant Professor,