Potential Impact of Antiviral Drug Use during Influenza Pandemic

Gani, Raymond; Hughes, Helen E.; Fleming, Douglas; Griffin, Thomas W.; Medlock, Jolyon M.; Leach, Steve

doi:10.3201/eid1209.041344

Cited by 190 publications

(188 citation statements)

References 23 publications

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“…We evaluated the role of intervention strategies incorporated in preparedness plans for the US, the United Kingdom (UK) and the Netherlands. We discuss the potential role of the different intervention strategies and compare our results with those reported in previous studies (van Genugten et al 2003;Longini et al 2004;Gani et al 2005;.…”

Section: Introductionsupporting

confidence: 59%

“…In the optimistic scenario, we assume high antiviral efficacy and coverage rates (upper-bound parameters in table 2). Similarly, the less optimistic scenario assumes lower-bound parameter values for the antiviral efficacy and coverage (Gani et al 2005) and the Netherlands (van Genugten et al 2002(van Genugten et al , 2003. …”

Section: Resultsmentioning

confidence: 99%

“…We compare the findings of our model for the intervention scenarios considered in Gani et al (2005). The baseline simulations for the UK, assuming R 0 Z1.9 (in the absence of any interventions; table 4), result in 3.6% case-fatality percentage (933 514 deaths), 43% clinical (26 million infections) attack rate and 50% hospitalization rate (13 million hospitalizations).…”

Section: Evaluation Scenarios For the Ukmentioning

confidence: 99%

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Assessing the role of basic control measures, antivirals and vaccine in curtailing pandemic influenza: scenarios for the US, UK and the Netherlands

Nuño

Chowell

Gumel

2006

J. R. Soc. Interface.

101

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An increasing number of avian flu cases in humans, arising primarily from direct contact with poultry, in several regions of the world have prompted the urgency to develop pandemic preparedness plans worldwide. Leading recommendations in these plans include basic public health control measures for minimizing transmission in hospitals and communities, the use of antiviral drugs and vaccination. This paper presents a mathematical model for the evaluation of the pandemic flu preparedness plans of the United States (US), the United Kingdom (UK) and the Netherlands. The model is used to assess single and combined interventions. Using data from the US, we show that hospital and community transmission control measures alone can be highly effective in reducing the impact of a potential flu pandemic. We further show that while the use of antivirals alone could lead to very significant reductions in the burden of a pandemic, the combination of transmission control measures, antivirals and vaccine gives the most 'optimal' result. However, implementing such an optimal strategy at the onset of a pandemic may not be realistic. Thus, it is important to consider other plausible alternatives. An optimal preparedness plan is largely dependent on the availability of resources; hence, it is country-specific. We show that countries with limited antiviral stockpiles should emphasize their use therapeutically (rather than prophylactically). However, countries with large antiviral stockpiles can achieve greater reductions in disease burden by implementing them both prophylactically and therapeutically. This study promotes alternative strategies that may be feasible and attainable for the US, UK and the Netherlands. It emphasizes the role of hospital and community transmission control measures in addition to the timely administration of antiviral treatment in reducing the burden of a flu pandemic. The latter is consistent with the preparedness plans of the UK and the Netherlands. Our results indicate that for low efficacy and coverage levels of antivirals and vaccine, the use of a vaccine leads to the greatest reduction in morbidity and mortality compared with the singular use of antivirals. However, as these efficacy and coverage levels are increased, the use of antivirals is more effective.

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Section: Introductionsupporting

confidence: 59%

Section: Resultsmentioning

confidence: 99%

Section: Evaluation Scenarios For the Ukmentioning

confidence: 99%

See 1 more Smart Citation

Assessing the role of basic control measures, antivirals and vaccine in curtailing pandemic influenza: scenarios for the US, UK and the Netherlands

Nuño

Chowell

Gumel

2006

J. R. Soc. Interface.

101

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“…3 Piecewise Linear Number of Infected Figure 2 plots the attack rate, p, which is directly proportional to the total number infected, T (f ), as a function of the fraction of initially exposed individuals, I 0 and reasonable values of R 0 for influenza transmission (Gani et al, 2005). If there are few that are initially infected due to exogenous exposure (small I 0 /S 0 ), then Appendix B justifies the following piecewise linear approximation for T (f ).…”

Section: System Settingmentioning

confidence: 99%

Supply Chain Coordination and Influenza Vaccination

Chick

Mamani

Simchi‐Levi

2008

Operations Research

203

184

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Billions of dollars are being allocated for influenza pandemic preparedness, and vaccination is a primary weapon for fighting influenza outbreaks. The influenza vaccine supply chain has characteristics that resemble the news vendor problem, but possesses several characteristics that distinguish it from typical supply chains. Differences include a nonlinear value of sales (caused by the nonlinear health benefits of vaccination due to infection dynamics) and vaccine production yield issues. We show that production risks, taken currently by the vaccine manufacturer, lead to insufficient supply of vaccine. Unfortunately, several supply contracts that coordinate buyer (governmental public health service) and supplier (vaccine manufacturer) incentives in industrial supply chains can not fully coordinate the influenza vaccine supply chain. We design a variant of the cost sharing contract and show that it provides incentives to both parties so that the supply chain achieves global optimization and hence gurantees sufficient supply of vaccine. Influenza is an acute respiratory illness that spreads rapidly in seasonal epidemics. Globally, annual influenza outbreaks result in 250,000 to 500,000 deaths. The World Health Organization reports that costs in terms of health care, lost days of work and education, and social disruption have been estimated to vary between $1 million and $6 million per 100,000 inhabitants yearly in industrialized countries. A moderate, new influenza pandemic could increase those losses by an order of magnitude (WHO, 2005).This paper provides background about influenza and vaccination, a key tool for controlling influenza outbreaks, then highlights some operational challenges for delivering those vaccines. One challenge is the design of contracts to coordinate the incentives of actors in a supply chain that crosses the boundary between the public sector (health care service systems) and private sector (vaccine manufacturers).Some experts suggest the U.S. government should promise to purchase a fixed amount of flu vaccine-despite the cost and the likelihood that some of the money would end up being wasted. Canada, for instance, has contracts with vaccine makers to cover most of its population. …That takes much of the risk out of the company's business, but still lets it manufacture additional doses for the private market… (WSJ, Wysocki and Lueck, 2006) I recently met with leaders of the vaccine industry. They assured me that they will work with the federal government to expand the vaccine industry, so that our country is better prepared for any pandemic. … I'm requesting a total of $7.1 billion in emergency funding from the United States Congress…(George W. Bush, 2005) We then present a model of a government's decision of purchase quantities of vaccines, which balances the public health benefits of vaccination and the cost of procuring and administering those vaccines, and a manufacturer's choice of production volume. We characterize the optimal decisions of each in both selfish and system...

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“…Past studies have estimated the reproduction number of individual influenza seasons, in particular for pandemics [11][12][13][14][15][16][17][18][19]. However, no study has yet reported estimates of the reproduction number for several countries and consecutive influenza seasons in the interpandemic period, where a fraction of the population is immune due to previous influenza exposure or vaccination.…”

Section: Introductionmentioning

confidence: 99%

Seasonal influenza in the United States, France, and Australia: transmission and prospects for control

2007

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SUMMARYRecurrent epidemics of influenza are observed seasonally around the world with considerable health and economic consequences. A key quantity for the control of infectious diseases is the reproduction number, which measures the transmissibility of a pathogen and determines the magnitude of public health interventions necessary to control epidemics. Here we applied a simple epidemic model to weekly indicators of influenza mortality to estimate the reproduction numbers of seasonal influenza epidemics spanning three decades in the United States, France, and Australia. We found similar distributions of reproduction number estimates in the three countries, with mean value 1.3 and important year-to-year variability (range 0.9-2.1). Estimates derived from two different mortality indicators (pneumonia and influenza excess deaths and influenza-specific deaths) were in close agreement for the United States (correlation = 0.61, P < 0.001) and France (correlation = 0.79, P < 0.001), but not Australia. Interestingly, high prevalence of A/H3N2 influenza viruses was associated with high transmission seasons (P = 0.006), while B viruses were more prevalent in low transmission seasons (P = 0.004). The current vaccination strategy targeted at people at highest risk of severe disease outcome is suboptimal because current vaccines are poorly immunogenic in these population groups. Our results suggest that interrupting transmission of seasonal influenza would require a relatively high vaccination coverage (> 60 %) in healthy individuals who respond well to vaccine, in addition to periodic re-vaccination due to evolving viral antigens and waning population immunity.

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Potential Impact of Antiviral Drug Use during Influenza Pandemic

Cited by 190 publications

References 23 publications

Assessing the role of basic control measures, antivirals and vaccine in curtailing pandemic influenza: scenarios for the US, UK and the Netherlands

Assessing the role of basic control measures, antivirals and vaccine in curtailing pandemic influenza: scenarios for the US, UK and the Netherlands

Supply Chain Coordination and Influenza Vaccination

Seasonal influenza in the United States, France, and Australia: transmission and prospects for control

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