The Ghost of Smallpox Past
Despite its being dead for 25 Years, the specter of a smallpox pestilence -- via terrorism -- haunts the public.
What is the Real Threat? continued...
Samuel A. Bozzette, MD, PhD, and colleagues at RAND Health Care
and the VA San Diego Healthcare System, have looked at several plausible
scenarios for smallpox emergencies. They aren't writing science fiction. It's a
dead-serious effort to come up with cost-benefit numbers to guide public health
readiness and response.
"How likely is a smallpox bioterror attack? That is a
matter for the government to judge," Bozzette tells WebMD. "The
president says the risk of imminent attack is low. And from scenarios we've
analyzed, the range of complexity required to actually carry out these attacks
varies quite widely."
In the worst-case scenario, mass public vaccination would save
about 30,000 lives. But there's a catch. We prevent those "what-if"
deaths at a cost of about 500 very real deaths from vaccine complications.
"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
The surprising conclusion: Mass smallpox vaccination, either
before or after a large-scale attack, won't do much net good. The reason lies
in the nature of smallpox itself.
Nobody doubts that smallpox is a terrible disease. It kills
some 30% of people who get it, and leaves many more terribly scarred for life.
There's no drug that can cure the disease.
It's quite contagious but generally, direct and fairly
prolonged face-to-face contact is required to spread smallpox from one person
to another. Smallpox also can be spread through direct contact with infected
bodily fluids or contaminated objects such as bedding or clothing. Rarely,
smallpox has been spread by virus carried in the air in enclosed settings such
as buildings, buses, and trains, according to the CDC.
It takes about 12-14 days for infection to incubate -- and by
the time a person is ready to spread the disease, that person is very ill. Most
cases are spread at bedside. That's why smallpox should be treated at home or
in special facilities, not in hospitals.