Feds to stockpile antivirals as pandemic "speed bump"

Lett, Dan

doi:10.1503/cmaj.050332

Cited by 3 publications

(5 citation statements)

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“…These interpretations of and apply for a totally susceptible community in which antiviral drugs are not used. The curves in Figure 4 display values of and for which in three scenarios, namely (a) antivirals are dispensed at onset of symptoms in the primary case (two days after infection), (b) antivirals are dispensed two days after onset of symptoms in the primary household case, [2] , [4] and (c) no antiviral drugs are dispensed. For each curve in Figure 4 , parameter pairs that lie below the curve satisfy , while for parameter coordinates above the curve.…”

Section: Resultsmentioning

confidence: 99%

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Can Antiviral Drugs Contain Pandemic Influenza Transmission?

Becker

Wang

2011

PLoS ONE

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Antiviral drugs dispensed during the 2009 influenza pandemic generally failed to contain transmission. This poses the question of whether preparedness for a future pandemic should include plans to use antiviral drugs to mitigate transmission.Simulations using a standard transmission model that allows for infected arrivals and delayed vaccination show that attempts to contain transmission require relatively few antiviral doses. In contrast, persistent use of antiviral drugs when the reproduction number remains above 1 use very many doses and are unlikely to reduce the eventual attack rate appreciably unless the stockpile is very large. A second model, in which the community has a household structure, shows that the effectiveness of a strategy of dispensing antiviral drugs to infected households decreases rapidly with time delays in dispensing the antivirals. Using characteristics of past pandemics it is estimated that at least 80% of primary household cases must present upon show of symptoms to have a chance of containing transmission by dispensing antiviral drugs to households. To determine data needs, household outbreaks were simulated with 50% receiving antiviral drugs early and 50% receiving antiviral drugs late. A test to compare the size of household outbreaks indicates that at least 100–200 household outbreaks need to be monitored to find evidence that antiviral drugs can mitigate transmission of the newly emerged virus.Use of antiviral drugs in an early attempt to contain transmission should be part of preparedness plans for a future influenza pandemic. Data on the incidence of the first 350 cases and the eventual attack rates of the first 200 hundred household outbreaks should be used to estimate the initial reproduction number R and the effectiveness of antiviral drugs to mitigate transmission. Use of antiviral drugs to mitigate general transmission should cease if these estimates indicate that containment of transmission is unlikely.

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Section: Resultsmentioning

confidence: 99%

“…The threat from avian influenza H1N5 prompted many countries to establish a stockpile of antiviral drugs, [1] , [2] , [3] , [4] , such as oseltamivir and zananivir. The size of the antiviral stockpile and its proposed use, therapy or prophylaxis, were keenly debated during the preparation of pandemic management plans.…”

Section: Introductionmentioning

confidence: 99%

Can Antiviral Drugs Contain Pandemic Influenza Transmission?

Becker

Wang

2011

PLoS ONE

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“…For the currently circulating strains of influenza, these drugs have been found to reduce the risk of infection in susceptible individuals (Hayden et al 2000(Hayden et al , 2004Welliver et al 2001;Monto et al 2002;Jefferson et al 2006), and to reduce the levels of virus shedding in infected individuals who are treated soon after symptom onset (Hayden et al 1996(Hayden et al , 1997(Hayden et al , 1999Nicholson et al 2000;Treanor et al 2000;Jefferson et al 2006). Many countries have or will obtain a stockpile of antivirals for use in an influenza pandemic (Cheng 2005;Lett 2005;Esveld 2006;Harrod et al 2006) and mathematical models have been used to investigate the relative benefit of using antivirals for prophylaxis and treatment ( Ferguson et al 2005;Longini et al 2005;Barnes & Glass 2007;McCaw & McVernon 2007) using data for the currently circulating influenza. However, the effectiveness of antivirals for a pandemic strain is not known, and strain-specific estimates of antiviral effectiveness will be urgently required to assist policy makers in making the optimal use of the stockpile.…”

Section: Introductionmentioning

confidence: 99%

“…Thus, the potential benefit of antivirals to reduce transmission is strongly influenced by the time that they are administered. These findings are reflected in the recommendations that antivirals will only be provided to individuals who are diagnosed within 2 days of symptom onset (Lett 2005;Harrod et al 2006). In the clinical trials of antiviral drugs, changes in infectivity over the infectious period are controlled by ensuring that study participants are given antivirals at a fixed time following exposure.…”

Section: Introductionmentioning

confidence: 99%

Estimating antiviral effectiveness against pandemic influenza using household data

Glass

Becker

2008

J. R. Soc. Interface.

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Current estimates of antiviral effectiveness for influenza are based on the existing strains of the virus. Should a pandemic strain emerge, strain-specific estimates will be required as early as possible to ensure that antiviral stockpiles are used optimally and to compare the benefits of using antivirals as prophylaxis or to treat cases. We present a method to measure antiviral effectiveness using early pandemic data on household outbreak sizes, including households that are provided with antivirals for prophylaxis and those provided with antivirals for treatment only. We can assess whether antiviral drugs have a significant impact on susceptibility or on infectivity with the data from approximately 200 to 500 households with a primary case. Fewer households will suffice if the data can be collected before case numbers become high, and estimates are more precise if the study includes data from prophylaxed households and households where no antivirals are provided. Rates of asymptomatic infection and the level of transmissibility of the virus do not affect the accuracy of these estimates greatly, but the pattern of infectivity in the individual strongly influences the estimate of the effect of antivirals on infectivity. An accurate characterization of the infectiousness profile—informed by strain-specific data—is essential for measuring antiviral effectiveness.

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“…[ 9 ] studied household-based interventions with the use of the antiviral drugs for the control of pandemic influenza. Antiviral drugs have been proven to be effective against currently circulating strains of pandemic influenza, so many countries set up a stockpile of antiviral drugs for preparedness plans [ 10 , 11 , 12 , 13 , 14 ]. However, the efficacy of antiviral drug against a new pandemic influenza strain is not yet known, and it is difficult to confirm whether current antiviral drug is effective or to what extent it is effective, against a novel influenza virus strain [ 14 ].…”

Section: Introductionmentioning

confidence: 99%

Antiviral Prophylaxis and Isolation for the Control of Pandemic Influenza

Zhang

Wang

2014

IJERPH

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Before effective vaccines become available, antiviral drugs are considered as the major control strategies for a pandemic influenza. However, perhaps such control strategies can be severely hindered by the low-efficacy of antiviral drugs. For this reason, using antiviral drugs and an isolation strategy is included in our study. A compartmental model that allows for imported exposed individuals and asymptomatic cases is used to evaluate the effectiveness of control strategies via antiviral prophylaxis and isolation. Simulations show that isolation strategy plays a prominent role in containing transmission when antiviral drugs are not effective enough. Moreover, relatively few infected individuals need to be isolated per day. Because the accurate calculations of the needed numbers of antiviral drugs and the isolated infected are not easily available, we give two simple expressions approximating these numbers. We also derive an estimation for the total cost of these intervention strategies. These estimations obtained by a simple method provide a useful reference for the management department about the epidemic preparedness plans.

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Feds to stockpile antivirals as pandemic "speed bump"

Cited by 3 publications

References 0 publications

Can Antiviral Drugs Contain Pandemic Influenza Transmission?

Can Antiviral Drugs Contain Pandemic Influenza Transmission?

Estimating antiviral effectiveness against pandemic influenza using household data

Antiviral Prophylaxis and Isolation for the Control of Pandemic Influenza

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