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Latent stage [d] for all ages determines the average duration from infection until onset of symptoms. In the program, seven successive latent stages are used to obtain a realistic distribution of its duration. The average duration is independent of the age group and risk group of the infected individual. Infected individuals in the last two of the seven latent stages can already be contagious (cannot be changed via sliders or input fields in the user interface). Using the pre-set mean value of 1.9 days for the latent stage, the contagiousness begins about half a day before onset of symptoms. |
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Asymptomatic and mild Disease [d] determines the average time of contagiousness (after latency) of cases with asymptomatic or moderate course. These durations depend on the age group. In the program, 19 successive stages are used to obtain a realistic distribution of the contagious duration. |
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Severe disease [d] determines the average time of contagiousness (after latency) for severely sick cases. This duration depends on the age group of the case, but is independent of the fact whether a patient can be taken care of at home or whether he or she needs hospitalization. In the program, 19 successive stages are used to obtain a realistic distribution of the contagious duration. The duration of contagiousness is identical with the duration of being sick. |
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Convalescence [d] working determines how many days on average working adults have to stay home after the end of their contagious period to recover from severe disease (i.e. do not go to work). Individuals with asymptomatic infection or mild disease do not stay home from work and do not have to revover after the end of their contagious period. In the program, only one stage is used for the convalescence of patients. The resulting exponential distribution of the sojourn time has a high variability, indicating highly different convalescence periods for different cases. |
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Sojourn times with a mean duration of 0 days lead to mathematical problems when solving the differential equations and are, therefore, not admitted in the program. |
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In section relative contagiousness relative to moderately sick cases, the average degree of contagiousness in the different stages of infection will be determined. |
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In section contagiousness during first half of infectious period, temporal changes in contagiousness are determined. |
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Severely sick children do not attend day care centers and do not go to school; severely sick adults do not participate in mass mass events. |
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Severely sick working adults do not go to work and, thereby, cause costs. |
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Modified average durations only re-distribute the contagiousness, but cannot increase or decrease the pathogen's ability to spread. As the user-supplied basic reproduction number must be kept valid at any time, any change in parameters can only re-distribute the contagiousness, but cannot generally increase or decrease it. |
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Latent stage [d] for all ages determines the height of the "exposed" curve. |
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Asymptomatic and mild Disease [d] determines the height of the curves which depict the asymptomatic and moderately sick cases. |
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Severe disease [d] determines the height of the curve which depicts severely sick cases. It also determines the duration of hospitalization and thereby determines the height of the curve of hospital beds which are occupied during the epidemic. |
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Severe disease [d] and Convalescence [d] working determine the height of the curve of the work loss caused by influenza and the corresponding cumulative curve and costs. |
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Latent stage [d] for all ages:
Longini IM Jr., Halloran ME, Nizam A, Yang Y: Containing pandemic influenza with antiviral agents. American Journal of Epidemiology 2004; 159: 623-633. |
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Asymptomatic and mild Disease [d] und Severe disease [d]:
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Convalescence [d] working:
The economic impact of influenza in Switzerland - interpandemic situation. |
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