Table 1 Parameter values for the agent-based model
From: Interventions to control nosocomial transmission of SARS-CoV-2: a modelling study
| Symbol | Description | Distribution/valuea | Source | |
|---|---|---|---|---|
| Incubation period | s(τ) | Time between infection and symptom onset |
Gamma distribution Shape = 5.807 Scale = 0.948 Mean = 5.510 SD = 2.284 | Lauer et al. [15] |
| Generation time | ω(τ) | Time between becoming infected and subsequent onward transmission events |
Weibull distribution Shape = 2.826 Scale = 6.839 Mean = 6 | Grassly et al. [14] |
| Proportion of asymptomatic infections among infected patients | \( {P}_A^p \) | 20% | Buitraga-Garcia et al. [20] | |
| Proportion of asymptomatic infections among infected HCWs | \( {P}_A^h \) | 31% | Buitraga-Garcia et al. [20] | |
| Proportion of severe symptomatic individuals | Ps | Proportion of exposed individuals that will develop severe symptoms | 20% | Wu et al. [21] |
| Reproduction number of asymptomatic infectees for wild-type variant | \( {R}_A^W \) | Mean number of infections caused by an individual asymptomatically infected with the wild-type SARS-CoV-2 variant | 0.5 | Calibrated to UMCU data |
| Reproduction number of symptomatic infectees for wild-type variant | \( {R}_S^W \) | Mean number of infections caused by an individual symptomatically infected with the wild-type SARS-CoV-2 variant | 1.25 | Calibrated to UMCU data |
| Reproduction number of asymptomatic infectees for new virus variant | RA | Mean number of infections caused by an individual asymptomatically infected with the SARS-CoV-2 variant | 0.8 (1.95) | Based on \( {R}_A^W \) with 56% higher transmissibility, varied in sensitivity analysis |
| Reproduction number of symptomatic infectees for new virus variant | RS | Mean number of infections caused by an individual symptomatically infected with the SARS-CoV-2 variant | 1.95 | Based on \( {R}_A^W \) with 56% higher transmissibility |
| Maximum sensitivity of diagnostic PCR test | 93.1% (79%) | Grassly et al. [14], varied in sensitivity analysis | ||
| Proportion of HCWs that work in the same ward as during their previous shift |
95% (baseline) 100% (intervention) | Assumed | ||
| PPE effectiveness | Reduction in infectiousness upon contact between an infected and susceptible individual (includes PPE efficacy and adherence) | 90% (50%, 70%) | Suzuki et al. [22], Qian et al. [23] and Bessesen et al. [24], varied in sensitivity analysis | |
| Isolation period for HCWs | Amount of time HCWs have to isolate after symptom onset or after being detected by screening or contact tracing | 7 days | Assumed | |
| Recovery time for asymptomatic infection | γA | Mean duration of an asymptomatic infection |
14 days Sensitivity analysis: Unif(9, 19) | Assumed |
| Recovery time for symptomatic (moderate, severe) infection | γS | Mean duration of a symptomatic infection |
14 days (moderate) 35 days (severe) Sensitivity analysis: Unif(9, 19) Unif(30, 40) | Liu et al. [16] |
| LoS of non-COVID patients in ICU |
Lognormal meanlog = 0.37 sdlog = 0.82 Mean = 1.45 days sd = 2.27 | Fitted distributions to UMCU data from 2014-2017 | ||
| LoS of non-COVID patients in normal ward |
Weibull Shape = 0.92 Scale = 4.18 Mean = 4.35 days | Fitted distributions to UMCU data from 2014-2017 | ||
| LoS of moderately infected patients |
Gamma Shape = 1.88 Rate = 0.25 Mean = 31.8 days sd = 30.08 | Fitted distributions to UMCU data from 2020 | ||
| LoS of severely infected patients |
Gamma Shape = 1.59 Rate = 0.05 Mean = 7.52 days sd = 636 | Fitted distributions to UMCU data from 2020 |