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Eric Toner, MD Speaker Biography | Summary | Audio Transcript
Monica Schoch-Spana:
It's a real pleasure to introduce my colleague, Dr. Eric Toner, who is going to talk to us today about what a modern-day flu pandemic will look like. Eric has 23 years of experience in emergency medicine, 20 of which have been specifically in disaster medicine. It is my pleasure to welcome Eric to the table. Thank you. [Applause] Eric Toner:
Thank you, Monica. Well, this is my topic–what would a modern-day flu pandemic look like, and I think I need to change the title to what might a modern-day flu pandemic look like because, I'll confess to you, I don't know. I need to give you a disclaimer, as does everybody else who talks about this. No one really knows what a pandemic would look like. Everything that we say in this topic is based on the three pandemics of the twentieth century: 1918, 1957 and 1968. Three is not a very big sample size [from] which to draw many conclusions, particularly because the information we have about 1918 is quite fragmentary. Remember, this was before the age of virology, so a lot of assumptions have been made. But, having given that disclaimer, I will go forward. The one thing we can say about pandemics–it certainly has been true about the last three–is they happen fast. This is a map of the United States in 1957, in August [note: refers to slide images]. The white represents states that were not affected by influenza, in pink are states in which ten percent of the counties were reporting cases, and in red are states in which fifty percent of the counties were reporting influenza. This is August. This is mid September. Two weeks later...two weeks after that...two weeks after that. From the beginning of the outbreak of the pandemic in 1957 until it involved every state was approximately two months. The same thing happened in 1918, and the same thing happened in 1968. I would also point out, as did D.A. [Henderson] earlier, this started in August. In 1918, it started in September--not typical months for flu. How bad would this be? These are the HHS's planning assumptions for influenza. They used two models: a moderate based on the 1968 pandemic, and a severe model based on the 1918 pandemic. Both models assume that thirty percent of the population will become infected, and half of those individuals will become sick and need medical care. The big difference is in the assumptions with regard to hospitalizations; there is roughly a tenfold difference. Derived from that is the number of people needing ICU care and the number of deaths. Those numbers really don't do you much good if you are trying to prepare a hospital or community. What you really need to do is know how many cases there will be in your community, because influenza will travel across the country in a moving wave and go through each community in a period of about two months. Using FluSurge which is a CDC program for modeling influenza in a community, we've taken the HHS planning assumptions, and what we find is [that] in the mild or moderate scenario, 19 percent of existing hospital beds would be occupied by flu patients at the peak, 46 percent of the ICU beds would be occupied, and 20 percent of the ventilators would be occupied. This doesn't looks so bad, except all of these resources are normally fully occupied on any given day, so where are we going to put the other patients? The situation is very different if you look at the severe scenario. In the severe scenario (which is the 1918 scenario), 191 percent of regular hospital beds would be occupied by flu patients alone, 461 percent of ICU beds would be occupied by flu patients alone and 200 percent, basically, of the number of ventilators would be in use by flu patients. Obviously, planning for this is much more difficult. This is the HHS worst-case scenario. I would point out that there is no biological reason to think that this is the worst-case scenario–this is just the worst that we have experienced. Is it realistic to expect that public health can prevent such a scenario? Let's talk about how you stop an epidemic. First, there are vaccines, and then there are antimicrobials. In this case antivirals are to be used either prophylactically or for treatment; and thirdly, there are disease containment efforts. Vaccines–flu is constantly changing. Therefore, you can't produce a vaccine in advance of a pandemic, you can't predict what the strain will be, [and] you can't stockpile. There is very little manufacturing capacity in the world for influenza vaccine, and we have a very old and slow production technology. Lastly, once a vaccine is produced, we can't be sure of how effective it will be–such [is] the problem we face now with the current trial vaccine. In regards to antivirals, we have a limited supply, and again, a limited production capacity, such that prophylaxis on a large-scale is not practical–there are just not enough drugs. Resistance develops rapidly with Amantadine, not quite so rapidly with Tamiflu, but it does develop. The dosage and duration of treatment needed varies from strain to strain, so all of our planning right now is based on using Tamiflu in its current dosage, which is used for seasonal flu. It appears that for H5N1 that dosage is insufficient; you would probably need twice the dose for twice the period of time. Timed treatment is critical; ideally you want to start antivirals within hours of the onset of symptoms. If you delay more than two days, it probably has no value at all. We have to have systems in place to be able to deliver these drugs to the right people in a short period of time. Disease containment...A lot of features go into disease containment. First of all, isolate the sick–that's a no-brainer. Identify and maybe quarantine those who are exposed, perhaps a geographic quarantine. Travel restrictions. Social distancing such as closing schools, canceling gatherings, avoiding crowds and staying three feet away from each other. Infection control [such as] restroom etiquette, hand washing, [and] using masks, gowns and gloves. There are problems with flu. It has a very short incubation period, two days on average, which gives you no time to trace contacts and implement quarantine. In seasonal flu, at least–and we think in the previous pandemics–there is both pre-symptomatic and asymptomatic spread. Perhaps as much as 50 percent of people who spread flu don't have significant symptoms. This means isolation could only be partially effective at best, and you can't identify all of the people who are spreading the disease. In addition, there is a very short time between generations, perhaps just 2-3 days, which means that it spreads very rapidly and there is no time to implement geographic quarantine, for example. One infected flu patient could become a million flu infected patients in 60 days. Is it realistic to expect that public health interventions will prevent the kinds of scenarios that we have talked about? Simple answer–it can't be stopped. At best, public health measures can slow the virus, but even this isn't proven. All of the measures that we have talked about to slow a pandemic have economic and societal costs, which may exceed their benefits. Is it realistic to expect that medical interventions will thwart the impact of a pandemic strain? In an ideal world, there would be unlimited surge capacity in the healthcare system, and all flu patients would be treated with normal health care standards, and healthcare would go on unaffected. But, let's take a look at the U.S. healthcare system. Thirty percent of U.S. hospitals are losing money, and of those that are profitable, they have an operating margin of about 1.9 percent. There are 45 million uninsured, and $25 billion a year in uncompensated care. We have shortages of healthcare workers across the board. Half of our emergency departments are at or over capacity, and turning away patients because there are not enough inpatient beds. Maybe the federal government can come in and help bail out the health care system? This is what Secretary Leavitt says about that, "Any community that fails to prepare with the idea that somehow in the end the central government will be able to rescue them will find out that they are tragically wrong." He has said it in 50 different states over the course of the last two months–they're not coming, they can't be there, [and] you're on your own. What are the most likely ethical and practical dilemmas that communities will face in trying to prevent additional infections and care for a large number of sick people during a pandemic? There are many, and we'll just list a few. First of all, how to allocate the scarce resources of vaccine and antivirals? How to allocate the scarce life saving medical resources, such as ventilators? If you only have one quarter of a number of ICU beds, and one-half the number of ventilators that you need, how do you decide who is going to get them? How do you ensure that all the hospitals in a given community are providing the same level of healthcare, that is, that they are all using similar processes to make these decisions? How do you make decisions about what other forms of healthcare aren't going to be provided during a pandemic? How do you enforce voluntary–or otherwise–isolation and quarantine? Thank you.... Q&A Session Arrietta Chakos:
I'm Arrietta Chakos, with the city of Berkeley, California. I have to say that your comments were very, very sobering. I'm sure we'll learn more from the panel now, but I was interested to hear earlier Dr. Henderson saying that he felt that quarantine, as a tactic, might not be as effective. I noticed that you do speak about that when you talk about using vaccines prophylactically, looking at antimicrobial use, and then public health enforcement. What practical measures can we look to in the communities if social isolation might be a step, but quarantine on a large-scale basis might be impossible? Eric Toner:
Well, I mentioned quarantine because it is in the national plans, and I think it is something we need to deal with from a scientific/public health standpoint. Like Dr. Henderson, I don't believe that quarantine is likely to be that useful. It may be of value to encourage people who have been exposed to voluntarily stay out of circulation if they can. But quarantine in the way that it is envisioned by many–particularly quarantine in which there is a governmental role in enforcement–is probably counterproductive. And certainly, geographic quarantine which is what many people think about when we talk about quarantine probably has no scientific basis. Proceedings of the May 23, 2006 Summit: Disease, Disaster, & Democracy Transcription by CastingWords
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