RESUMO
BACKGROUND: Vaccination for the 2009 pandemic did not occur until late in the outbreak, which limited its benefits. Influenza A (H7N9) is causing increasing morbidity and mortality in China, and researchers have modified the A (H5N1) virus to transmit via aerosol, which again heightens concerns about pandemic influenza preparedness. OBJECTIVE: To determine how quickly vaccination should be completed to reduce infections, deaths, and health care costs in a pandemic with characteristics similar to influenza A (H7N9) and A (H5N1). DESIGN: Dynamic transmission model to estimate health and economic consequences of a severe influenza pandemic in a large metropolitan city. DATA SOURCES: Literature and expert opinion. TARGET POPULATION: Residents of a U.S. metropolitan city with characteristics similar to New York City. TIME HORIZON: Lifetime. PERSPECTIVE: Societal. INTERVENTION: Vaccination of 30% of the population at 4 or 6 months. OUTCOME MEASURES: Infections and deaths averted and cost-effectiveness. RESULTS OF BASE-CASE ANALYSIS: In 12 months, 48 254 persons would die. Vaccinating at 9 months would avert 2365 of these deaths. Vaccinating at 6 months would save 5775 additional lives and $51 million at a city level. Accelerating delivery to 4 months would save an additional 5633 lives and $50 million. RESULTS OF SENSITIVITY ANALYSIS: If vaccination were delayed for 9 months, reducing contacts by 8% through nonpharmaceutical interventions would yield a similar reduction in infections and deaths as vaccination at 4 months. LIMITATION: The model is not designed to evaluate programs targeting specific populations, such as children or persons with comorbid conditions. CONCLUSION: Vaccination in an influenza A (H7N9) pandemic would need to be completed much faster than in 2009 to substantially reduce morbidity, mortality, and health care costs. Maximizing non-pharmaceutical interventions can substantially mitigate the pandemic until a matched vaccine becomes available. PRIMARY FUNDING SOURCE: Agency for Healthcare Research and Quality, National Institutes of Health, and Department of Veterans Affairs.
