Thread by @AliHMokdad

.@IHME_UW has released a major update to our #COVID19 estimation framework: a multi-stage hybrid model with new estimates for projected U.S. deaths. These projected death totals have sadly nearly doubled. Please follow for my analysis of why. 1/15
covid19.healthdata.org/projections

Our hybrid model builds on our old mortality model since we still believe “mortality” is more accurate than “infected” due to testing. This model is our envelope of death (i.e., maximum number of deaths). 2/15
healthdata.org/covid/updates

The added model is a susceptible, exposed, infected, recovered (SEIR) model that accounts for testing and diagnosis. 3/15

The number of projected deaths increased due to (1) increased mobility before the relaxation, (2) premature relaxation of social distancing, (3) addition of presumptive deaths (assumed COVID but not confirmed), and (4) outbreaks like those in the Midwest. 4/15

There are several factors that we are now accounting for in our models : 5/15

a) Heat - We do see a reduction in transmission with increased temperature. 6/15

b) Testing - When testing rates increase, we detect cases earlier and are able to conduct tracing and isolation, thereby reducing the circulation of the virus. 7/15

c) Population Density - We account for density by using the % of the population of each state that lives in a place of 1,000 or more per square kilometer. 8/15

d) Mobility - The most important factor is mobility as people are moving more in areas where the virus circulation remains elevated.* 9/15

* Note that increased mobility might be different than before as people could be practicing better social distancing than before by staying away from one another and wearing masks. 10/15

The premature relaxation, however, is resulting in an increase in deaths though that could have been avoided had the relaxation been delayed until better mitigation infrastructure (testing, tracing, etc.) was in place. 11/15

The worst was behind us for this first wave of the virus HAD we kept social distancing in place until the end of May (and possibly earlier for some states). Now the worst may unfortunately be ahead for some parts of the U.S. 12/15

For areas of the country that are reopening, I urge people to take precautions (physical distancing, masks, handwashing, limiting frequency of outings) to help reduce the number of projected deaths. 13/15

I know this balance is an incredibly difficult one. Many of my friends have lost their jobs, so I know firsthand how many people are hurting economically. 14/15

I hope that the combination of a heat effect, coupled with expanded testing capacity and contact tracing, can accelerate the speed at which we can get people back to work. END /