BioterrorQ&A

February 15, 2003

In the wake of last weekend's heightened alert for terrorist attacks, including the possible use of chemical and biological agents, News deputy editorial page editor Thom Beal interviewed the state's chief medical officer, Dr. Ned Calonge, about Colorado's preparedness.

News: Are you convinced that a bioterror attack of some sort on the United States is a clear and present danger?

Calonge: We get information from two directions - from the Centers for Disease Control and Prevention and the U.S. Department of Health and Human Services. The federal government has given Colorado $16.6 million in bioterrorism program funding and is continuing to give us preparedness directions. That tells me that the people who have access to intelligence feel preparedness is an issue of enough importance that we need to be prepared for a potential clear and present danger.

Now, they're very careful, and President Bush was careful as well, to say that there is no imminent threat of smallpox being introduced into the United States. It's a possibility, not a probability. So to answer your question, my feeling is that the risk is high enough that preparedness efforts are justified.

News: The Rand report published in The New England Journal of Medicine in December said a smallpox vaccination policy must be based on judgments about the probability of an attack. You and other state authorities must have determined the probability of an attack in Colorado. What is it and what kind of attack do you consider the most likely should one occur?

Calonge: Your question really gets to the heart of how we quantify an unknown risk and then respond to it. And that's really what we're trying to do; we're trying to make sure we're in line with directions from the CDC, HHS and the White House, but also ensure that our response is measured to our own perception of risk. So let's talk about the likely scenarios for how smallpox could be introduced into Colorado.

For a terrorist an easy way would be to infect a person and send him to Denver International Airport with the objective of coming into contact with as many people as possible. But it's not a very efficient delivery system. What it really would do is create chaos and fear because, once infected, a person looks terrible and feels worse. They can't really hide their symptoms and they can't move around much because they feel so awful. Onlookers would scatter. So the probability of infecting a lot of people that way is really quite small. A more effective attack would be for the terrorist infected with smallpox to show up at Denver Health. I mean the chaos and the fear that it would produce would be remarkable.

News: But we do have an international airport.

Calonge: We've planned around that possibility, since that would be the easiest way to actually do it. But would you fly into DIA or into Los Angeles, San Francisco, Miami or New York? I mean, whether you pick a high-profile city versus somewhere in the heartland, those are value assumptions and opinions that are difficult to make. It would be easier to fly into a port city.

News: Do you think the probability of a bioterror event in Colorado will increase if the United States wages a war against Iraq?

Calonge: I think that if Saddam Hussein ordered something like that, it would be an act of desperation, a last-ditch effort. But if we go to war in Iraq, yes, that would increase the probability.

News: Only a handful of workers and first responders have been vaccinated for smallpox. Even at Denver Health, Denver's major trauma and terrorism response center. Two questions: How can we handle a smallpox emergency if we don't have enough health care workers and first responders vaccinated? And are the safety and liability issues being resolved?

Calonge: We've taken a conservative approach in trying to determine the risk of exposure versus the risk from the vaccination. By conservative, I mean erring on the side of vaccinating fewer rather than more people.

The purpose of pre-vaccination is that you don't have to post-vaccinate, you don't have to vaccinate people after exposure. Unique to smallpox is that you can successfully immunize people after they've been exposed and completely prevent them from getting the disease.

We have about a three-day window of opportunity after infection, so when you look at that you have to ask "Well then, what would be the aim of a pre-vaccination strategy?" The No. 1 aim, in my opinion, is to have groups of vaccinated vaccinators. Why? Because first of all, I don't have to vaccinate them before they go out into the field. The second is that they are a guaranteed work force; I don't have to worry that 30 to 36 percent of them could be sick a week after their vaccinations, or that I could lose them to a negative vaccine response.

From a public health standpoint, we also need vaccinated laboratory people who are going to handle samples, and for the same reason a group of medical epidemiologists who can do contact tracing out in the field. So for me, the state and local smallpox response teams in these three areas - laboratory testing, disease control and vaccinators - are the most important.

News: These are the people that need to be vaccinated?

Calonge: Right. Ahead of time.

News: Do we have enough?

Calonge: Yes. We'll have about 22 vaccinated professionals from the Colorado Department of Public Health and Environment's staff. We could dispatch them even today at a moment's notice to take over those functions in response to a case appearing anywhere the state.

News: And that's enough?

Calonge: It's enough in the case of the scenario of one response to one hospital. If we had a multisite attack, with people arriving at every hospital in the state, we'd have to adjust and implement a slightly different strategy. But I believe with the partners that we have - I don't have those numbers yet, but we had as many as 250 volunteers in local health departments sign up for vaccinations - then I say yes, we have our response team.

We have partners in 15 local public health departments in the state's most populated counties. I think that's enough. If we get less than that, if we're left with maybe 100 or 150 people total, again the primary first activity would be to immunize everyone exposed and then immunize a group of immunizers. The great thing about immunization is that it can expand exponentially. So if I'm an immunizer, I can immunize 20 people in an hour and they can each immunize 20, and so on.

News: Wouldn't a multisite attack necessitate vaccinating the public?

Calonge: Well, it really depends. I mean it depends on where people were exposed. Mass vaccination would really be the last option.

News: Are we prepared for that?

Calonge: We have a mass vaccination plan. We were actually asked to do that first. But then with subsequent guidance from the CDC, we decided not to attempt vaccinating the entire population within five days. Rather, we moved to the tried-and-true approach of the ring vaccination.

News: Which means?

Calonge: It's important to recognize that smallpox was not eradicated through mass vaccination. It was eliminated through ring vaccination. Such that if there's one case I figure out who that person has come into contact with, then I find those people and I immunize all of them. Then I ask those people with whom they've been in contact with, and so there's the second ring.

The idea about moving beyond ring to mass vaccination, and the way that it was worded in our guidance from the federal government, was that when covering an entire community, an entire county, an entire state, the ring is so big that you really are just as well off going out and getting everyone immunized. And that decision would be made at the time with the facts in hand. But when I say multiple sites, I'm thinking more of 100 infected people flying into the state, they disperse before it's apparent they're infected, and they arrive at hospitals or other places throughout the state on the same day. Then our current plan is to immunize a second round of immunizers that could then go out to localities.

Just one last issue; there's been a lot of discussion about response models built around whether or not you could aerosolize smallpox and deliver it through the air rather than via a human vector. The problem here is that we don't have any information about that. We don't know if it's possible. We don't know what volume of distribution it would take. We don't know how it would be delivered or if it would even be effective. One of the great things about the air and water is that there's a huge volume of distribution and the dilutional activities are really quite extreme. So exploding something over Denver - it's hard to actually put together a theoretical model that could determine whether that would be an effective dispersal technique for the virus. Putting smallpox into the air supply in an enclosed public place is just not something we've had any experience with. That's not to say it's not possible.

News: Our state is also rural, with remote areas and geological communications, weather and cultural obstacles. Does Colorado have the medical, technical and logistical expertise to detect a bug and respond outside the Denver area?

Calonge: I'm going to tell you that we don't have all of the education done, so I can't tell you I know every physician in Colorado in every rural community would recognize smallpox if it walked into his or her office. But it is our plan to get that training done.

But we do have the ability to get our people on planes and to any place in the state at the drop of a hat. That part of our emergency management has always been there. If we have to respond with medications and vaccines, or distribute them from National Pharmaceutical Stockpile, the federal government would assist us. We have the Spanish issue very well covered. And we do have some capacity in other languages, but would rely on our links with community-based organizations for help.

News: In June 2001, the mock bioterror attack exercise "Dark Winter" revealed what one governor called an "unclear division" of duties between state and federal emergency responders. Are you satisfied that two years on the division of labor is clear?

Calonge: I believe that it's clear. Those of us who work in state government, we know that in the event of an bioterror event the FBI would be in charge. The governor's office, the Office of Emergency Management, they recognize the FBI's role. But we would, of course, be right there at the core of any emergency activities.