Study Predicts Impact of Smallpox Attack

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Study Predicts Impact of Smallpox Attack

 

By <A

HREF= " http://aolsvc.health.webmd.aol.com/content/Biography/7/1756_53105.htm " >Dan\

iel DeNoon</A>

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hael Smith, MD</A>

on Thursday, December 19, 2002

Dec. 19, 2002 -- More than 40,000 people would die if there were a

large-scale smallpox bioterror attack on an airport, researchers calculate.

 

 

It's a horrible thing to think about. But that worst-case scenario must be

considered in the debate over whether it's a good idea to vaccinate everyone

against smallpox. What are the real risks from smallpox? That's the focus of

several reports in an extraordinary early release from the Jan. 30, 2003,

issue of The New England Journal of Medicine.

 

 

The most provocative of these reports is a calculation of the risks from

various smallpox-attack scenarios. Samuel A. Bozzette, MD, PhD, and

colleagues at RAND Health Care and the VA San Diego Healthcare System pose a

number of " what if " scenarios. These range from an accidental laboratory

release to a major bioterror attack on a large airport.

 

 

The surprising finding: Even a worst-case scenario doesn't justify mass

public vaccination before there is an attack.

 

 

" Our study shows that in order for there to be a substantial advantage for

mass vaccination of the public, we would need to be facing a significant

threat of a very widespread attack, " Bozzette tells WebMD. " This is because

the conventional methods of containment -- vaccination of contacts and

isolation of the ill -- work reasonably well. If we were to vaccinate the

public, thousands would become ill and 500 or so people would die. "

 

 

If only healthcare workers were vaccinated before a large-scale attack, about

43,000 people would die. Prior mass vaccination would cut this to about

13,000 deaths. But the cost of preventing those " what if " deaths would be the

500 very real vaccine-related deaths.

 

 

" The main issues are that smallpox isn't an instant killer, and that there is

a lot of vaccine on hand, " Bozzette tells WebMD. " If there is an attack,

there will be time to carry out a widespread vaccination program. This should

reassure people. "

 

 

Despite this reassurance, the calculations show that mass public vaccination

after an attack would not do a lot of good. However, the study does show that

advance vaccination of healthcare workers is worthwhile. That's because

healthcare workers run a much higher risk of infection.

 

 

" Basically, there will be harm associated with distribution of the vaccine, "

Bozzette says. " Healthcare workers are only 3% of the population, but in our

study, we would predict they would be 20%-60% of all the cases. Moreover,

healthcare workers need to stay healthy and confident they are protected in

order to operate the health system for all of us. So since there is greater

risk, the benefit threshold is lower for vaccination of healthcare workers.

And because they are so many fewer in number, the number harmed is much

smaller. We estimate 25 deaths -- which is still not nothing. "

 

 

So would Bozzette get the smallpox vaccine? What about his family?

 

" I think we can look to the example of what the president is doing with his

family as what an informed judgment might look like, " Bozzette says. " I am an

infectious-disease specialist; I am going to be vaccinated. My wife is a

pathologist; she is going to be vaccinated. But my children, my parents, my

sisters, and their children are not going to be vaccinated. Our family knows

they are not helping the nation by getting vaccinated. They understand that

even if there is an outbreak they are not likely to be infected and that

there will be time to get vaccinated. "

 

 

The Risk of Smallpox Bioterror

A smallpox attack on an unvaccinated U.S. public would be " catastrophic, "

said D.A. Henderson, MD, MPH, Johns Hopkins University distinguished service

professor and senior science advisor to the secretary of Health and Human

Services, an a previous interview. Henderson's standing -- he was a leading

force in world smallpox eradication -- convinces some bioterror experts that

a smallpox attack is a worst-case scenario.

 

 

Others are not so sure. One is Kent A. Sepkowitz, MD, director of infection

control at Memorial Sloan Kettering Cancer Center and associate professor of

medicine at Weill Medical College, Cornel University, New York.

 

 

" Remember Y2K. This is a comparable non-event, " Sepkowitz tells WebMD.

 

Another is Thomas Mack, MD, MPH, professor of preventive medicine, Keck

School of Medicine, University of Southern California, Los Angeles. Like

Henderson, Mack is a veteran of the world war on smallpox. He led teams that

investigated some 100 smallpox outbreaks. His NEJM editorial argues that

smallpox is overrated as a bioterror weapon.

 

 

" A smallpox attack is not a worst-case bioterror scenario, " Mack tells WebMD.

" People greatly exaggerate the danger to the population not directly

affected. They picture smallpox being transmitted like wildfire, and that

doesn't actually happen. It is more like a grenade than like a dirty bomb.

Once the initial wave of infections is over, mopping up is relatively

simple. "

 

 

Unlike many other diseases, people with smallpox can't infect other people

until they start to feel ill -- a couple of weeks after infection. And if

people know they've been exposed, getting vaccinated within a few days can

keep them from getting sick. Both these facts mean health workers have time

to stop a smallpox epidemic before it gets out of hand.

 

 

" Suppose the worst case: the aerosolization of live smallpox virus applied to

a substantial population, say into a shopping center, " Mack says. " Maybe if

there was some way to keep it in the air, then, yes, under very extreme

circumstances you could infect a large number of people. But the average

number of people they infect is not going to change [from what we've seen in

natural epidemics]. They don't get smallpox from weaponized virus any more,

but from somebody's mouth. If they are put in hospitals, they will be

dangerous. But once a first case appears, every community will find a place

to put people away from the general hospital population. "

 

What Americans Don't Know About Smallpox

One of the most striking NEJM papers is a survey of what Americans know --

and, mostly, don't know -- about smallpox and smallpox vaccination. Robert J.

Blendon, ScD, professor of health policy and political analysis Harvard

School of Public Health, and colleagues conducted telephone interviews with a

national sample of 1,006 adults.

 

 

Among the striking findings:

 

84% of Americans don't know that right now there is enough smallpox vaccine

to vaccinate everyone in the U.S. in the event of a smallpox attack.

63% of Americans think there's been a case of smallpox somewhere in the world

in the last five years. And 30% think there's been a recent case of smallpox

in the U.S. The reality: There hasn't been a case of smallpox since 1977 --

anywhere.

78% of Americans think there is an effective treatment for smallpox. The

reality: There is no such treatment.

58% of Americans don't know that vaccination within a few days of smallpox

exposure can prevent disease.

73% of Americans say they'd get smallpox vaccination if their own doctor and

most other doctors were vaccinated. However, this number fell to just 21% if

their own doctor and many other doctors refused vaccination.

 

Smallpox Vaccine Risks

 

What will happen if lots of people start getting vaccines based on

decades-old technology? The answer: Many people will suffer side effects, and

some -- an estimated one to five in a million -- will die.

 

 

But there's good news. One of the most feared side effects of public

vaccination is the accidental spread of the live-virus vaccine from a

vaccinated person to an unvaccinated person. People with damaged immune

systems -- such as transplant recipients, people taking immune-suppressing

treatment for arthritis and other conditions, cancer patients on

chemotherapy, and AIDS patients -- are at enormous risk of vaccine

complications.

 

 

Are these people at risk from vaccinated people? Not much, according to the

NEJM report from Sepkowitz. The Weill Medical College professor took a

careful look at all the medical literature on the topic.

 

 

" The vaccine virus is very uncontagious, " Sepkowitz tells WebMD. " It would

take the wrong person being in the wrong place at the wrong time -- and a

[break with] standard infection control practices in hospitals for a person

to get secondary disease. The risk will be small but not zero. "

 

 

Mack, however, argues against mass public vaccination.

 

" This is the most dangerous live vaccine we have, " he says. " It is going to

kill people. It may be just a few people in a million, but it still will kill

people. Overall, vaccinating people in general is not cost effective. It will

hurt more people than it helps. I think even vaccinating people who work in

hospitals is not effective. We will hurt more people than we save. If someone

showed me evidence that someone is planning sustained multiple attacks, I

would change my mind. "

 

Should I Get the Smallpox Vaccine?

Eventually, smallpox vaccination will be available for all Americans. The

decision on whether to get vaccinated is personal. There is a risk. Is the

benefit worth the risk? Most of the experts who spoke with WebMD agree with

Blendon: Ask your doctor.

 

" Decisions are best made on a rational, factual basis and not on the basis of

fear, " Edward W. Campion, MD, NEJM senior deputy editor, tells WebMD.

" Physicians do have a major role. If there is going to be any type of

widespread vaccination, patients are going to be coming to doctors to ask,

'Should I be vaccinated or not? What is your opinion?' "

 

This makes it more important than ever for doctors to be informed -- and to

be aware that they are role models.

 

" At this moment I am making the decision as frontline person to get

vaccinated, but I am not having my family vaccinated, " Blendon says. " That is

important for people to know. It is more important for patients to know what

their doctor says than what a cabinet secretary says. Physicians are

critical. People are going to be watching what they say. "

 

SOURCES: The New England Journal of Medicine, Jan. 30, 2003 • Samuel A.

Bozzette, MD, PhD, RAND Health Care and VA San Diego Healthcare System •

Robert J. Blendon, ScD, professor of health policy and political analysis,

Harvard School of Public Health • Edward W. Campion, MD, senior deputy

editor, NEJM • Kent A. Sepkowitz, MD, director of infection control, Memorial

Sloan Kettering Cancer Center; and associate professor of medicine at Weill

Medical College, Cornel University, New York • Thomas Mack, MD, MPH,

professor of preventive medicine, Keck School of Medicine, University of

Southern California, Los Angeles • D.A. Henderson, MD, MPH, Johns Hopkins

University distinguished service professor; and senior science advisor to the

secretary of Health and Human Services.

© 2002 WebMD Inc. All rights reserved.