Effectiveness and cost-effectiveness of expanded antiviral prophylaxis and adjuvanted vaccination strategies for an influenza A (H5N1) pandemic.

BACKGROUND

The pandemic potential of influenza A (H5N1) virus is a prominent public health concern of the 21st century.

OBJECTIVE

To estimate the effectiveness and cost-effectiveness of alternative pandemic (H5N1) mitigation and response strategies.

DESIGN

Compartmental epidemic model in conjunction with a Markov model of disease progression.

DATA SOURCES

Literature and expert opinion.

TARGET POPULATION

Residents of a U.S. metropolitan city with a population of 8.3 million.

TIME HORIZON

Lifetime.

PERSPECTIVE

Societal.

INTERVENTIONS

3 scenarios: 1) vaccination and antiviral pharmacotherapy in quantities similar to those currently available in the U.S. stockpile (stockpiled strategy), 2) stockpiled strategy but with expanded distribution of antiviral agents (expanded prophylaxis strategy), and 3) stockpiled strategy but with adjuvanted vaccine (expanded vaccination strategy). All scenarios assumed standard nonpharmaceutical interventions.

OUTCOME MEASURES

Infections and deaths averted, costs, quality-adjusted life-years (QALYs), and incremental cost-effectiveness.

RESULTS OF BASE-CASE ANALYSIS: Expanded vaccination was the most effective and cost-effective of the 3 strategies, averting 68% of infections and deaths and gaining 404 030 QALYs at $10 844 per QALY gained relative to the stockpiled strategy.

RESULTS OF SENSITIVITY ANALYSIS

Expanded vaccination remained incrementally cost-effective over a wide range of assumptions.

LIMITATIONS

The model assumed homogenous mixing of cases and contacts; heterogeneous mixing would result in faster initial spread, followed by slower spread. We did not model interventions for children or older adults; the model is not designed to target interventions to specific groups.

CONCLUSION

Expanded adjuvanted vaccination is an effective and cost-effective mitigation strategy for an influenza A (H5N1) pandemic. Expanded antiviral prophylaxis can help delay the pandemic while additional strategies are implemented.

PRIMARY FUNDING SOURCE

National Institutes of Health and Agency for Healthcare Research and Quality.