Time-varying IHR

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Goal

We want to have a single source of truth for the mathematical formulation of the time-varying IHR. This allows for time-varying ratio of hospital admissions to genomes shed in wastewater (since we are starting by not allowing that quantity to vary). This could be due to new variants emerging with differences in severity, or for differences in the age distributions of infections. We want to be able to use this to immediately code up the math decided upon here.

Context

This was discussed in the 2024-02-27 meeting (see minutes) and agreed upon in the ADR record under model_features.md. This specific feature should be the same as what's implemented in the existing wastewater model. Completion of this task will allow us to implement the feature more quickly and should facilitate creation of a model design document.

Required features

• mathematical description of the time-varying IHR
• source for intercept of IHR estimate
• add to the feature to the model design document
• Include an independent test that checks TBD.
• Include documentation in the code using docstring

Out of scope

• This does not include code, just specification of the feature in math/writing

Related documents

• Model feature prioritization
• Existing wastewater model definition

Ref: https://github.com/cdcent/cfa-multisignal-renewal/issues/74
author: @kaitejohnson