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Table 1 Terminology and definition

From: A model-based economic analysis of pre-pandemic influenza vaccination cost-effectiveness

Terminology

Definition

Pandemic characteristics

Moderate pandemics

A moderate pandemic is defined as a pandemic with a transmissibility of R = 1.9 and case fatality rate of 0.25%.

Severe pandemics

An extreme pandemic is defined as a pandemic with a transmissibility of R = 2.7 and case fatality rate of 1.5%.

Vaccinations

Pre-emptive vaccination

A two-dose pre-emptive vaccination strategy is considered assuming that individuals should be vaccinated with pre-pandemic vaccine annually. This pre-pandemic vaccine should be updated in every 10 years and a pandemic will emerge within a 30 year time frame.

Reactive vaccination

A two-dose reactive vaccination strategy is considered assuming that individuals are naïve to the pandemic virus and such reactive vaccines will be available after 6 months of the pandemic emergence.

Scenarios

Scenario 1

No pandemic occurs in the 30 year time frame and people have been pre-emptive vaccinated annually.

Scenario 2

A pandemic occurs in the 30 year time frame with a virus that does not match pre-pandemic vaccines i.e. vaccine efficacy is 0%. Reactive vaccines will be developed and administrated.

Scenario 3

A pandemic occurs in the 30 year time frame with a virus that matches pre-emptive vaccines with vaccine efficacy of 30%.

Scenario 4

A pandemic occurs in the 30 year time frame with a virus that matches pre-emptive vaccines with vaccine efficacy of 75%.

Social distancing and antiviral interventions

Limited duration school closure

School were closed for 8 weeks of time as follows: for a primary school the whole school was closed if 1 or more cases were detected in the school; in a high school only the class members of the affected class were isolated (sent home and isolated at home) if no more than 2 cases were diagnosed in a single class; however if there were more than 2 cases diagnosed in the entire high school the school was closed.

Sustained school closure

All schools were closed simultaneously after a pandemic emerges.

Community contact reduction

Community contact reduction was modelled by assuming that on days when the intervention was in effect all individuals made 50% fewer random community contacts. This intervention is also modelled for either limited duration or sustained.

Antiviral treatment and prophylaxis

Antiviral drugs used for treatment and prophylaxis of household members (of a symptomatic case) were combined with vaccination and social distancing interventions. It was assumed that 50% of symptomatic individuals would be identified for antiviral treatment and/or prophylaxis, and that treatment and prophylaxis would occur 24 hours after the appearance of symptoms.