Estimating the United States Demand for Influenza Antivirals and the Effect on Severe Influenza Disease During a Potential Pandemic

Abstract

Following the detection of a novel influenza strain, A(H7N9), we modeled the use of antiviral treatment in the United States to mitigate severe disease across a range of hypothetical pandemic scenarios. Our outcomes were total demand for antiviral (neuraminidase inhibitor) treatment and the number of hospitalizations and deaths averted. The model included estimates of attack rate, healthcare-seeking behavior, prescription rates, adherence, disease severity, and the potential effect of antivirals on the risks of hospitalization and death. Based on these inputs, the total antiviral regimens estimated to be available in the United States (as of April 2013) were sufficient to meet treatment needs for the scenarios considered. However, distribution logistics were not examined and should be addressed in future work. Treatment was estimated to avert many severe outcomes (5,200–248,000 deaths; 4,800–504,000 hospitalizations); however, large numbers remained (25,000–425,000 deaths; 583,000–3,700,000 hospitalizations), suggesting that the impact of combinations of interventions should be examined.

Influenza Vaccination Modifies Disease Severity Among Community-dwelling Adults Hospitalized With Influenza

“…We excluded 8% of participants due to unknown vaccination status that could inadvertently introduce bias; however, the number was not large, and when we compared the excluded group’s characteristics related to vaccination, severity, and time from disease onset to hospitalization, we did not find any substantial differences (Supplementary Table A1). We performed our analyses among hospitalized patients treated with antivirals, excluding untreated patients (less than 20% of FluSurv-NET patients) [16], and this could also have underestimated the effect of vaccination on influenza-associated severe outcomes as antiviral treatment can attenuate disease severity [39]. …”

Partnering for enhanced digital surveillance of influenza‐like disease and the effect of antivirals and vaccines (PEDSIDEA)

“…Uniform outcome measures will facilitate the comparison of medical interventions in multicentre clinical trials and post‐marketing surveillance. Regulatory authorities in Europe and North America have called for standardized clinical outcome measures to facilitate the systematic evaluation of antiviral drugs . WHO priorities, at the same time, indicate that next‐generation influenza vaccines should mostly prevent severe disease outcomes.…”

“…The mean ViVI Score was 13.72 (SD 5.81; range 0-35) given a possible maximum score of 48, while the median score (IQR) was 14 (9)(10)(11)(12)(13)(14)(15)(16)(17)(18). Figure 2A,B plots the distribution of the VIVI Score for the whole cohort and by study site.…”

Pandemic Risk Assessment Model (PRAM): a mathematical modeling approach to pandemic influenza planning

“…Individuals from compartments (1)-(4) (outlined in blue) may be exposed to the virus, and can move to the exposed (5) compartment. These individuals will develop infections that will or will not require medical attention, dependent on the severity of the virus and their risk status, moving either into the medically attended compartment (6), or the not medically attended compartment (7). Persons who are exposed to an infectious person but do not become infected are not included in this category.…”

“…Mathematical models provide an opportunity to evaluate the potential impacts of decisions and help to plan for efficient use of public resources. Models simulating influenza pandemics and mitigation strategies in the literature follow one of three broad structures: (i) static Markov chain [3][4][5][6][7][8][9], (ii) deterministic compartmental (with stochastic elements in some cases) [5,6,, and (iii) network or individual/agent-based stochastic [31][32][33][34][35][36][37][38][39][40][41][42][43]. Within these categories, which themselves are quite fluid, there is a great deal of diversity.…”