The White House CDC Plan for Opening America Up Again has three phases and some general recommendations that span all three phases.  Modeling the recovery phase in our analysis tool requires quantifying the features of a this phased approach so we can drive inputs into our model space. The weighted table below quantifies the dynamic parameters that we use in our model.

1. General Population Transmission Factor ( > 20 Years Old): Relative to the baseline, this parameter reduces the number of potentially infectious contacts a day within the general population.  In the reopening phases we apply the following values to this factor:

  • Baseline = 1
  • Phase 1 = 0.2
  • Phase 2 = 0.4
  • Phase 3 = 0.6
  • After = 0.8

2. School Age Transmission Factor (< 20 Years Old): Relative to the baseline, this parameter reduces the school age contact rate.  Full school and youth activities are represented by 1, which is the baseline.  Partial school activities will be reflected as a fraction.  During a lock-down periods, the interaction will generally be set to the same factor as the general population.  In the phases of reopening, this may differ from the general population transmission factor as schools and other youth activities resume.  In the reopening phases the following assumptions are made:

  • Baseline = 1
  • Phase 1 = 0.2 (same as general population)
  • Phase 2 = 0.6 to 1 (0.6 summer school and limited sports , 1 full school and sports)
  • Phase 3 = 1 (full activity)
  • After = 1 (children and youth are not likely to mirror general population social distancing and hygiene practices).

3. Vulnerable Risk Factor: Vulnerable people are the elderly and those with preexisting comorbidity conditions or compromised immune systems.  If a victim is categorized as vulnerable (over 70 or with category bin 5 immune system status), the risk of infectious transmission is reduced by this factor.  Here are the values we apply to the different phases:

  • Baseline = 1
  • Phase 1 = 0.05
  • Phase 2 = 0.1
  • Phase 3 = 0.2
  • After = 0.2

Below is the allocation matrix showing the Before, Phase 1, Phase 2, Phase 3 and After allocations affecting these three parameters.  The allocation of weights and reduction factor points are balanced.  Measures which have a direct effect on reducing infectious contacts receive heavier weighting.  Reduction points reflect a best estimates of the effectiveness of the each measure with respect to the “Before” condition.  Note that Sweden is included for reference: they have been implementing a strategy that is slightly more relaxed than Phase 1.

 

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