# 2296
PEP, or Post-Exposure-Prophylaxis, is one strategy of how we might best use antiviral medications (ie. Tamiflu/Relenza) during a pandemic.
The idea behind PEP is that once someone is identified as having pandemic influenza in a family (or a business, nursing home, etc.), that those people who have been exposed to the patient are given a 10-day prophylactic course of antiviral medications.
There are basically three uses for antivirals:
- Treatment of those infected
- Outbreak Prophylaxis for people who are likely to be exposed
- PEP (Post Exposure Prophylaxis) - giving antivirals to those exposed, but not yet symptomatic to prevent infection.
In the HHS's Proposed Guidance on Antiviral Drug Use during an Influenza Pandemic, released in June of this year, the concept of PEP was discussed, but the idea was not officially endorsed.
The limiting problem is the amount of antiviral medications it would require.
Without adding PEP, the HHS working group has determined that the number of courses of antivirals the United States needs on hand for a pandemic would be at least 195 million
Roughly 2.4 times more than the government intends to purchase.
They urge that the private sector, mostly businesses - but `families and individuals as appropriate' - stockpile the rest.
This would provide:
- 6M doses for deployment overseas to try to stop an outbreak
- 79M treatment courses for the infected here in the United States
- 103M courses to provide prophylaxis for healthcare and emergency service workers
- 5M courses for outbreak control in Nursing homes, prisons, and other closed settings
- 2M courses for people who are severely immuno-compromised
With an anticipated Federal and State Stockpile (currently lagging behind the goal) of 81 million courses, this means that the private sector would have to make up the 114 million course shortfall.
The authors of this HHS document point out that more than 150,000 American lives could be saved if households had antivirals available for PEP, or Post Exposure Prophylaxis.
The working group falls short of actually recommending household PEP, explaining:
Despite these potential benefits, however, further work is needed to assess the feasibility of this strategy and identify approaches for purchasing and stockpiling the antiviral drugs to support its implementation. Therefore, the working group makes no recommendation for household antiviral PEP at this time.
To implement household PEP would require another 106 million courses of antivirals, bringing the total needed to just over 300 million courses.
Today we get a press release announcing the publication of what the authors refer to as the first study on the cost-effectiveness of PEP in the United States.
Cost-Effective Antiviral Strategy Could Halve Pandemic Deaths
Article Date: 14 Sep 2008 - 9:00 PDT
Treatment with the oral antiviral oseltamivir combined with post-exposure prophylaxis (PEP) of people exposed to infected individuals could be one of the most cost-effective strategies for reducing illness and death during an influenza pandemic according to recent modeling research published in Value in Health by Beate Sander et al., University of Toronto, Ontario, Canada.
The objective of the study was to analyze, from a US societal perspective, the potential economic impact of a number of key mitigation strategies that may be considered in the event of a pandemic.
Combined targeted antiviral treatment / PEP is a cost-saving strategy and the most effective single approach for mitigating pandemic influenza. The addition of school closure provides greater benefit. Although this remains cost-effective from a societal perspective, school closure will most likely be an attractive strategy when transmission / mortality rates are high.
This analysis is the first economic evaluation to be performed using a dynamic model to predict influenza transmission, the model being based on a "typical" American community of 1.6 million individuals. The study evaluated the use of 16 alternate strategies based on the use of oseltamivir for both treatment and post-exposure prophylaxis (PEP), the use of pre-vaccination in 70% of the population, the use of school closure to reduce the spread of disease and the absence of any intervention.
It should be noted that the author's of this study have extrapolated a much higher number of lives saved by the use of PEP than did the HHS working group.
These sorts of models all depend on the numbers you feed into them. Attack rates, transmission rates (R0 number), and CFR (Case fatality ratios). Right now, all of these numbers are guesses. No one really knows what the next pandemic will bring.
As statistician George E. P. Box told us, "All models are wrong, but some are useful".
But even the more conservative estimates from the HHS indicate that having enough antivirals on hand to implement a PEP strategy could save 155,000 lives.
Cost effective or not, the real barrier here is the `will', on the part of the public or private sector, to invest in hundreds of millions of additional courses of antivirals before a pandemic starts.
And right now, relatively few appear anxious to do so.
