Age dependent branching ratios between compartments.

Our values for αi and μi are from those consolidated by the COVASIM program, Refs. [76] and [77]. We use IFR’s from data from LMIC’s taken from fits in the paper of Ref. [78], where the following formula is derived: log10(IFR) = −3.27 + 0.0524 * age. We modify only the δi for the 80+ age group to account for the leveling off of mortality in older age groups described by Ref. [24]. The IFR for each age group can be obtained as IFRi = (1 − αi)(1 − μi)δi. We use the estimated δi numbers as our initial IFRs, although when we allow them to vary as part of our minimization strategy to find the effective IFR’s we multiply all δi’s by a single smooth time-varying factor, optimizing this against data.