Table 2 Description of model parameters and their values
Parameters | Description | Value (range) | Source |
|---|---|---|---|
\(c\) | Number of contacts of an individual per unit time | 10 (5–20) | [28] |
\({p}_{sc}\) | The transmission rate of the virus when a susceptible person contacts an infected person | 0.5 (0.4–0.7) | [29] |
\(p\) | The ratio of susceptibility of vaccinated individuals to symptomatic individuals | 0.8 | Assumed |
\({\beta }_{SE}\) | Effective contact rates of susceptible individuals with viruses in the environment | 0.00414 (0.001–0.01) | [30] |
\({f}_{s}\) | The effective protection rate of the vaccine | 68.7% (58.1–76.7%) | [31] |
\({\tau }_{S}\) | Rate of quarantined susceptible individual releasing from quarantine, reciprocal of its average quarantine time | 1/7 | Assumed |
\({\tau }_{V}\) | Rate of quarantined vaccinated individual releasing from quarantine, reciprocal of its average quarantine time | 1/7 | Assumed |
\(\theta\) | Proportion of infected people with symptoms | 0.8 (0.5–0.9) | China CDC |
\({\sigma }_{I}\) | Reciprocal of the average latent period of symptomatic infections | 1/4.0 (1/4.4–1/3.5) | [32] |
\({\sigma }_{A}\) | Reciprocal of the average latent period of asymptomatic infections | 1/4.0 (1/4.4–1/3.5) | [32] |
\({\delta }_{I}\) | The transfer rate of symptomatic infected individuals who were detected and admitted to hospital through health monitoring, reciprocal of the average time from being infectious to detection through health monitoring | 1/2 | Assumed |
\(\delta\) | The transfer rate of quarantined exposed individuals who were detected and admitted to hospital through health monitoring | 1/4 | Assumed |
\({\gamma }_{I}\) | The natural recovery rate of symptomatic infected individuals, the reciprocal of infectious period in symptomatic infected | 1/10 (1/14–1/7) | China CDC |
\({\gamma }_{A}\) | The natural recovery rate of asymptomatic infected individuals, the reciprocal of infectious period in asymptomatic infected | 1/7 (1/10–1/5) | China CDC |
\({p}_{I2R}\) | Proportion of symptomatic infected persons who were not detected and recovered spontaneously | 0.025 | Assumed |
\({p}_{A2R}\) | Proportion of asymptomatic infected persons who were not detected and recovered spontaneously | 0.025 | Assumed |
\({\gamma }_{H}\) | The average recovery rate of hospitalized individuals, reciprocal of hospitalization period | 1/14 (1/20–1/10) | China CDC |
\({\eta }_{A}\) | The rate at which asymptomatic infected individuals shed virus into the environment | 0.05 (0.01–0.1) | [30] |
\({\eta }_{I}\) | The rate at which symptomatic infected individuals shed virus into the environment | 0.1 (0.02–0.2) | [30] |
\({\mu }_{P}\) | Virus mortality in the environment, the reciprocal of the average virus survival time | 1/5 (1/10–1) | [30] |
\(q\) | Proportion of infected individuals detected by nucleic acid testing | 0.8 | [33] |
\({q}_{E}\) | Proportion of exposed individuals detected by nucleic acid testing | 0.4 | Assumed |
\(n\) | Number of close contacts per infected individual | 50 | Assumed |
\(k\) | Frequency of nucleic acid testing | 3 | Assumed |
\({p}_{C}\) | Probability that close contacts are successfully traced and isolated | 0.9 | [34] |
\({p}_{V}\) | Proportion of close contacts who are vaccinated individuals | Determined by the ratio of \(V/N\) before nucleic acid testing | |
\({p}_{S}\) | Proportion of close contacts who are susceptible individuals | Determined by the ratio of \(S/N\) before nucleic acid testing | |
\({p}_{E}\) | Proportion of close contacts who are exposed individuals | Determined by the ratio of \(E/N\) before nucleic acid testing | |