Smallpox – What’s the threat?
By John Messmer, M.D.

About 40 percent of Americans have not been vaccinated against smallpox. In 1972 we stopped vaccinating children. The military ceased its smallpox vaccination program in 1990. The reason – there has not been a case of smallpox in the United States since 1949 nor in the world since 1977. The World Health Organization declared smallpox to be eradicated worldwide in 1980 as a result of an aggressive program of vaccination.

If you think this sounds like an ideal setting for terrorists to use smallpox as a weapon, think again. The virus is spread in secretions so only infected people can spread smallpox. Unlike chickenpox which can be spread before the person looks sick, people with smallpox have a distinct rash and look and act ill at the time they are contagious so they can be avoided. One must be very close to the infected person to contract the disease although spread through air ducts has been reported. In prior outbreaks, most secondary infections occurred among household members and treating medical personnel.

So why not just start vaccinations again and take away the worry? The reason is that smallpox vaccine is not as safe as other vaccines we use regularly. Other vaccines can not cause disease and side effects are very rare if used properly. To vaccinate against smallpox, a living virus called vaccinia is introduced into the skin through multiple shallow punctures. The person actually develops an infection with vaccinia and often feels ill with fever, aches, and so on. After recovery from vaccinia the person is immune to smallpox.

Unlike other vaccines, about one in a thousand people who are vaccinated develop serious reactions and one or two per million may die from the vaccine. To complicate matters, the vaccinated person can spread the virus to others from the open pustule created during vaccination and from the bandages used to cover the vaccination site. Vaccination sites must be monitored and kept clean, with regular dressing changes. The vaccinated person may tolerate the vaccine, but family or friends may be injured without being vaccinated. In the 1960’s one in five deaths from the vaccine were in unvaccinated individuals according to the New England Journal of Medicine.

People with chronic skin diseases, such as, eczema are at greatest risk as are those with impaired immune systems including people with HIV, transplant patients, those receiving cancer treatment, infants and the elderly. Many medical organizations and public health authorities are weighing the benefit vs. risk of introducing wide spread inoculation programs because of these concerns.

To reduce the risk to the general population, some authorities recommend distributing vaccine strategically but not vaccinating until a case of smallpox is identified. After contact with smallpox, the disease can be prevented by vaccination within four days of exposure. In addition, giving concentrated antibodies against smallpox can boost the protection. Vaccination programs could be aimed at people living in the area of the outbreak to provide a “ring” of immunity to stop its spread.

Smallpox may sound scary in the news, but knowledge may be the best weapon against it. For more information go to: http://www.hmc.psu.edu/healthinfo/s/smallpox.htm or http://www.bt.cdc.gov/agent/smallpox/index.asp .