This report was commissioned by the Department of Health and Ageing. It uses mathematical transmission models to evaluate the alternative interventions available for the control of an emerged pandemic of influenza. Data from past pandemic and currently circulating influenza strains guide the choice of values for model parameters.
In reading this report it is useful to bear in mind that a glossary of terms is given in Appendix A and values used for the many parameters of the modeling work are given in Appendix B. The latter also contains a discussion of data sources.
The report begins with a brief background statement (Section 1), followed by an introduction to the basic model structures and important concepts used in the report (Section 2). Particular attention is paid to the key concepts of basic reproduction number (R0) and infectiousness function, and to the measures used to judge the effectiveness of various public health interventions.
Section 3 evaluates border control measures primarily in terms of their effect on the likely delay between a pandemic being initiated overseas and being imported and gathering momentum in Australia. The additional delay resulting from restricting travel from the infected source region, screening travelers, promoting early presentation of newly-arrived travelers, and instigating partial home quarantine for all arriving travelers is quantified. We also present a method for deciding when Australia should consider implementing border control measures.
Section 4 evaluates interventions aimed at limiting transmission once the infection has been imported. Measures evaluated include early case isolation, personal infection control and distancing, quarantining affected households, closing schools, closing non-essential workplaces, prohibiting mass public gatherings, and the use of antiviral drugs. This section also examines the effect of time-delays in implementing interventions on the subsequent course of the epidemic.
Section 5 evaluates the use of antiviral drugs in greater detail. A range of strategies for the use of the antiviral drugs (who gets the drugs and when) are modeled to assess their contribution to reducing transmission, containment and delaying the epidemic. The implication for the antiviral stockpile is also assessed.
Section 6 assesses the role that health workers may play in spreading disease, and how the extent of this transmission and their risk of infection are reduced by protection through the use of antiviral drugs and personal protective equipment. The likely load on the health-care system in terms of influenza cases requiring hospitalisation is assessed for a range of scenarios.
We discuss limitations of the modeling results, and suggest where further work is needed.
The report concludes with a discussion section in which we comment on the reasons for the main results and their sensitivity to underlying assumptions. Issues that have not yet been addressed adequately are also pointed out.
Many calculations have been conducted for this report. It is hoped that these modeling results will be of help to policy makers. A large number of other calculations could have been conducted, different issues could have been addressed and issues could have been addressed differently. It is hoped that the results obtained so far, and the gaps in these results, will help to identify what other calculations would be particularly useful.