Smallpox Vaccine and Eczema Don't Mix
Combination Can Cause Severe, Possibly Deadly Infection
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.
'"The very real dangers associated with the live [smallpox] vaccine may take on a greater urgency today than decades ago given the current numbers of people with pre-existing medical conditions that put them at risk for serious side effects," Leung's colleague Julie Kenner, MD, PhD, says in a news release. Kenner is with the University of Hawaii.
It is unclear how many eczema patients would actually develop the vaccine-related skin infection -- known as eczema vaccinatum -- if immunizations were resumed. Data from the early 1970s showed that the infection was most common among young children, and 123 cases occurred among 1 million vaccinees. In a European study, 6% of those who got the infection died from it.
The CDC estimates that if the vaccine were given to everyone in the U.S., about 300-500 people would die from adverse reactions. After a two-day meeting in June, the Advisory Committee on Immunization Practices recommended that preemptive vaccinations be given only to people considered to be at high risk. In the event of an actual smallpox outbreak, the vaccine could be given within four days of exposure to lessen the severity of the illness or prevent it.