Smallpox Vaccine and Eczema Don't Mix Sept. 9, 2002 -- As many as half of all Americans are poor candidates for smallpox vaccination due to a rare, but potentially fatal, skin infection caused by the vaccine, health officials report. They conclude that mass immunization against smallpox in the absence of an identified bioterrorist attack may do more harm than good.

Immunologist Donald Leung and colleagues report that smallpox vaccination poses a threat to people with a history of the skin condition known as eczema, with the risk being particularly great for children. Being in close contact with someone who has recently been vaccinated can also be dangerous for those who have the skin disease or have had it. Leung tells WebMD that the frequency of eczema has tripled among children in the years since smallpox vaccinations were routinely given. Studies now suggest that up to 15% of people have a history of eczema.

"If 15% of the population has had [eczema] and each has a parent or sibling who [will be in] close contact, we are talking about nearly 50% of the population being excluded from vaccination," says Leung, who is head of pediatric allergy-immunology at Denver's National Jewish Medical and Research Center.

He adds that a national smallpox vaccination campaign makes sense only if it is voluntary, or if it is in response to a bioterrorist attack. The findings are reported in the September issue of the Journal of Allergy and Clinical Immunology.

"If we are under attack, everyone should be immunized because 30% of individuals die from smallpox and [in this event] the vaccination is much safer than getting the disease," he says.

The last case of smallpox occurred in the U.S. in 1949, and the disease was declared eradicated worldwide in 1980 by the World Health Organization. The virus is now believed to exist only in controlled labs at the CDC in Atlanta and in Russia. But in the days following the Sept. 11 attacks, government officials began hammering out a strategy to deal with its potential use as a biological weapon.

The live virus smallpox vaccine has one of the highest rates of adverse reactions of any now given. In addition to the severe skin infection, deadly side effects can include brain swelling and widespread toxicity occurring primarily in people with weakened immune systems.