MILWAUKEE -- Smallpox vaccines could do more harm than good for people with AIDS or allergic skin diseases, according to research presented in the September 2002 issue of the Journal of Allergy and Clinical Immunology (JACI). The JACI is the peer-reviewed, scientific journal of the American Academy of Allergy, Asthma and Immunology (AAAAI).
Smallpox vaccines were discontinued in the United States in 1972, and the disease was considered eradicated by 1980. However, the threat of bioterrorism has brought renewed concern about an outbreak of the disease and consideration by government officials for possible mass vaccination efforts.
Of all vaccines being used routinely today, the live virus smallpox vaccine (called vaccinia) has one of the highest rates of adverse reactions. With this in mind, the possibility of mass public smallpox vaccination must be carefully considered, according to lead review author Renata J.M. Engler, MD, FAAAAI, chief of allergy/immunology at the Walter Reed Army Medical Center in Washington, DC.
"The current CDC guidelines in the setting of a smallpox outbreak include a recommendation to immunize anyone with contact regardless of risk factor for an adverse event," Engler said. "Many expert groups are reviewing these questions and considering the fine points of risk-benefit and what other options exist to protect those patients who are at very high risk for serious or even life-threatening smallpox vaccine complications."
Because more people have immune deficiencies or skin diseases now than 30 years ago when the smallpox vaccine was regularly administered, researchers anticipate there could be a greater risk for adverse reactions among these groups.
People expected to be vulnerable to the side effects include patients with congenital or acquired immune deficiency diseases such as AIDS; people on immunosuppressive drugs, such as those undergoing organ transplantation; and people with active or inactive atopic dermatitis and potentially other skin conditions that affect the skin's outer layer.
Atopic dermatitis, sometimes called eczema, is an itchy skin condition, characterized by thickened red and scaly patches. It commonly affects the face in infants, and the inner elbows and knees, neck and eyelids in children and adults. While the precise cause of atopic dermatitis is unknown, the immune system of the skin is altered, and the disease can often be seen in individuals with a personal or family history of asthma or allergic rhinitis (hay fever).
Eczema vaccinatum (EV) is a risk for people who have atopic dermatitis or have had it in the past. The risk exists if they are exposed to vaccinia directly through vaccination, or indirectly by contacting someone who has recently been vaccinated. In this reaction, the vaccinia virus spreads unchecked throughout the skin, and, at its worst, could cause scarring, blindness, and even death. Vaccinia immune globulin (VIG) has been used successfully to treat or moderate this complication, if given soon after the reaction starts.
Current CDC smallpox vaccine guidelines recommend not vaccinating people with a current or past history of atopic dermatitis. Because rates of atopic dermatitis in developed countries have increased two- to three-fold (up to 15 percent in the U.S. population) since the days of routine smallpox vaccination, it is possible that up to half of the population may not be eligible to receive the smallpox vaccine under routine preventive circumstances, said paper co-author Julie Kenner, MD, PhD, adjunct clinical professor of dermatology at the University of Hawaii John A. Burnes School of Medicine in Honolulu, Hawaii.
With these groups at risk for severe reactions from the vaccine, it may prove difficult to include the majority of the population in a routine mass smallpox vaccination campaign. However, if the risk of smallpox infection is high, such as after a bioterrorism attack, the benefit of vaccination in some patients with atopic dermatitis may outweigh the risks of the vaccine, Kenner said.
"The very real dangers associated with the live vaccinia virus 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," Kenner said. "It is incumbent upon the medical community to protect our population to the best of our ability against these potentially lethal vaccine side effects, while at the same time, protect them from a very deadly disease."
The paper's authors recommend that additional research be conducted to explore how the immune system responds to vaccinia to better understand why people with atopic dermatitis are susceptible to EV, and how the reaction can be prevented.
The AAAAI is the largest professional medical specialty organization in the United States representing allergists, asthma specialists, clinical immunologists, allied health professionals and others with a special interest in the research and treatment of allergic disease. Allergy/immunology specialists are pediatric or internal medicine physicians who have elected an additional two years of training to become specialized in the treatment of asthma, allergy and immunologic disease. Established in 1943, the academy has more than 6,000 members in the United States, Canada and 60 other countries. The academy serves as an advocate to the public by providing educational information through its Web site, www.aaaai.org/, or the toll-free physician referral information line at (800) 822-2762.