September 2003

I hope you all had a wonderful summer. It’s amazing how time flies. I wish all of your children a great school year.

Dr. Barenfeld

Smallpox------------------------------------------------

The threat of smallpox as a weapon of bioterrorism has garnered a lot of media attention and, as such, public fear since 9/11/01. Misinformation about smallpox is common according to a recent study, not only for the lay public but for physicians as well. People are misinformed about whether the disease still exists, about how protective the vaccine is, and about whether smallpox can be treated effectively. I hope to answer many of your questions about a disease I have never seen and knew almost nothing about until that terrible September day.

Smallpox is a contagious disease caused by the variola virus. It is estimated to have caused 500 million deaths in the 20th century. Older data show a mortality rate of approximately 30% for patients infected with smallpox. Infants, the elderly, pregnant women, and immune deficient persons had the highest mortality rate. There is no effective treatment for smallpox and antibiotics will not help. Smallpox has been totally eradicated as a result of mass vaccination. The last naturally occurring case of smallpox was in Somalia in 1977 and it was officially declared eradicated in 1980. Mass vaccination in the U.S. ended in 1972. Presently, the virus only exists in 2 government laboratories in the U.S. and Russia. Fear exists that the Soviets may have developed the means to spread the virus in manmade aerosols. With Russian government funding for its laboratories declining in recent years, concern has arisen that the virus, along with the expertise to propagate a large amount of it, has fallen into unauthorized hands. Several characteristics of smallpox make it a possible agent for bioterrorism:

1. It can be produced in large quantities.
2. It can be made stable for storage and transportation.
3. It would likely cause significant disruption of society – as it is highly contagious, associated with high mortality rate, and most of the world has little or no immunity.

Most bioterrorism experts, however, believe that using smallpox as a weapon is highly unlikely, and there is no hard evidence that smallpox has been made into an aerosol.

Smallpox vaccination is highly effective. Those people who were vaccinated prior to 1972 may still have some protection from severe disease but no one knows for sure. Currently the CDC stores about 100 million doses of vaccine which can be diluted, and still be effective, and would be sufficient to immunize the entire U.S. population. The vaccine is a live vaccine that produces some immunity 10 days post vaccination and protects about 97% of vaccinees for five years. If a person were exposed to smallpox, he or she should be vaccinated within three or four days. The vaccine can be protective if administered less than seven days after exposure.

The procedure for smallpox vaccination differs from other vaccines commonly used. First, alcohol must not be used to clean the skin as it has been shown to inactivate the vaccine. A special needle is then dipped into the vaccine vial and then through a series of jabs a drop of the vaccine is injected into the skin of the upper arm. At least three jabs are made followed by three more if no trace of blood appears within 15 – 20 seconds. The site is then covered with gauze and loosely taped. The vaccine site will then develop into a blister which will eventually form into a scab and fall off in about 14 – 20 days leaving the classic scar that many of you have seen. Since the smallpox vaccine is live, the vaccine site can transmit the disease to others until the scab falls off. So it is very important to keep the vaccine site covered and not touch it until the area is well healed.

Complications from smallpox vaccine are common and can be quite serious. A recent report found that 36% of vaccinees were sufficiently ill to miss school, work, recreational activities or to have trouble sleeping. About 70% of children who were vaccinated for the first time experienced a fever. Studies from the 1960’s showed an overall rate of complications among first-time vaccinees of 1,254 for every 1 million. At least 40 people for every 1 million immunized will develop a significant and potentially life-threatening complication. The incidence of death from vaccination is estimated to be one in one million. Certain individuals shouldn’t get the vaccine due to an increase in incidence of complications. These include patients with a history of eczema (affects about 15% of population) or other chronic skin conditions, pregnancy or plans to become pregnant within one month of vaccination, breastfeeding and immunosuppressed persons. Close household contacts of these people should not be vaccinated as well. There are also recent reports of more than a dozen people who have developed severe heart problems post vaccination so the CDC has recommended that people with a history of heart disease should not be vaccinated as well. I should also mention that children < 1 year also should not be vaccinated.

Based on all of the above information the U.S. government has developed a three stage vaccination strategy. Phase 1: A limited number of first responders and public health investigation teams are vaccinated. First responders are not rigorously defined but generally include hospital-based personnel who would be required to assess and care for people with smallpox. The federal government believes there to be about 500,000 people that would need to be vaccinated in Phase 1. Only about 26,000 volunteers have been vaccinated in this phase so far. Phase II: Widespead immunization of health-care workers is done. This would total about 10 million vaccines. Phase III: All citizens (except those at increased risk of vaccine complications) can submit to voluntary vaccination. Phase III would not commence until 2004 at the earliest. In addition the CDC has developed a plan for immediate mass vaccination that would occur only in the event of a verified smallpox threat.

So should you be vaccinated against smallpox? Well, that is a decision for you and your family to make. I have tried to provide a balanced article that answers most of the common questions concerning smallpox, discussing some of the pros and cons for vaccination, as well as the U.S. government’s current position on vaccination.