Table S2.
Parameters used in the model simulation
| Parameter | Meaning | Values | Source/remarks | ||
|---|---|---|---|---|---|
| β | Transmission rate from symptomatic infection | 0.06 for R0=1.3 (Increases in proportion to R0) | Calculated in order to yield assumed value of R0 for different waves in India, by evaluating spectral radius of next-generation matrix (e.g. as described earlier2) | ||
| η | Amongst those exposed, rate of developing infectiousness | (1/3-1/5)/day | Corresponds to an average latent period of 3-5 days: Together with the period of pre-symptomatic transmission (see r below), corresponds to an overall average incubation period of 4-6 days3 | ||
| p (sym) | Proportion developing symptoms | 1/3-2/3 | Wide variation noted in individual studies and meta-analysis4-6 | ||
| k | Relative infectiousness of asymptomatic versus symptomatic infection | 2/3-1 | |||
| r | Amongst those with pre-symptomatic infection, rate of developing symptoms | 1/day | Assumption, corresponds to mean pre-symptomatic duration of one day | ||
| γ | Recovery rate | 0.2/day | Assumption, corresponds to mean infectious period of five days7 | ||
| wa | Per-capita rate at which post-infection immunity wanes | (1/365-1/120)/day | Assuming mean duration of immunity lasts for four months to one year8 | ||
| Parameter | Meaning | Age groups (yr) | Source/remarks | ||
|
| |||||
| <24 | 24-60 | >60 | |||
| CFRj | Case fatality rate in age Group I | 0.1% | 1.45% | 10.9% | Represents proportion dying amongst those with symptoms. Drawn from a recent study from two Indian States1 |
| µj | Mortality rate for severe cases | 0.0002/day | 0.0029/day | 0.0245/day | Hazard rates of µi are calculated to yield case fatality rates, using: CFRi=µi/(µi+γ) Uncertainty in the mortality hazards are considered +/−25% |
| Nj | Population (India) | 46% | 44.5% | 9.5% | Extrapolated from the Census of India 20119 |
| mij | Connectivity matrix between age Group I with age Group J | 1.37 | 1.43 | 0.05 | Drawn from reference1. Uncertainty in the each element of the contact matrix is considered +/−5% |
| 2.52 | 2.90 | 0.10 | |||
| 0.28 | 0.34 | 0.02 | |||
There remains much uncertainty about parameters relating to SARS-CoV-2 natural history, e.g., infectiousness of asymptomatic people relative to symptomatic ones and, duration of pre-symptomatic period, etc., In this study we adopted a range of parameter values to reflect this uncertainty in our model projections; we sampled uniformly from the parameter ranges shown here.