Back in the late 1780s, Edward Jenner, an observant English physician, realized that milkmaids infected with cowpox (a viral infection transmitted from cows to humans) caused a milder blistering disease than smallpox. And even more importantly, those who'd had cowpox did not develop smallpox.

Jenner correctly presumed that infecting individuals with cowpox offered protection against lethal and widepsread smallpox, the so called "scourge of Europe". In 1796, he boldly, although crudely innoculated fluid obtained from cowpox blisters into a healthy 8 year old boy. Hence the smallpox vaccine was born. By 1801, more than 100,000 English citizens had been vaccinated.

World wide vaccination through public health intitiatives spurred on by the World Health Organization eradicated natural smallpox from the planet. Routine U.S. vaccinations were discontinued in 1972. The military continued to receive them until 1990. Now with bioterrorist threats, the President has unveiled his smallpox vaccination plan, the largest national vaccination campaign in more than 30 years. Here are important answers regarding what you should know about this vaccine.

What is the smallpox vaccine made of?

Currently a single vaccine is available; Dryvax made by Wyeth Laboratories. This is a freeze-dried calf lymph vaccine containing live, attenuated vaccinia (cowpox) virus, not variola (smallpox). Vaccinia is related to smallpox, being a member of the orthopox family (which consists of smallpox, cowpox, monkeypox, mousepox, camelpox and rabbitpox).

It has been shown that diluted Dryvax vaccine (1/5th the strength) is as effective as the original concentration used up through 1972.

The vaccine also contains a variety of antibiotics and potential allergens including:

• Chlortetracycline Hydrochloride
• Neomycin Sulfate
• Polymyxin B Sulfate
• Streptomycin Sulfate

Anyone with a known allergy to the above should not receive the smallpox vaccination.

A tissue cell culture derived vaccine composed of vaccinia virus is currently being developed by Acambis/Baxter Laboratories. Two tissue cells are being investigated; human fibroblasts and Vero monkey kidney cells. It is hoped that one of these will successfully grow the vaccinia virus and yield a vaccine with fewer potential side effects than the current vaccine. The goal is to use the newer vaccine once mass vaccination begins for the general public.

How is the vaccine given?

The smallpox vaccine is not given like a traditional injection. A 2-pronged (bifurcated) needle is used. It is dipped into the vaccine and the skin is pricked 15 times. While not deep, small droplets of blood may be seen. The skin is never cleansed with alcohol prior to the vaccination as it can inactivate the vaccine.

Where is the vaccine given?

The vaccine is given on the upper outer arm (deltoid). Previous use on areas such as the back allowed the virus to spread across larger regions that lacked natural anatomic boundaries.

How do I care for the vaccination site?

The vaccination site can exude live cowpox until fully healed. This means that touching the area with bare hands can result in spreading the virus to other parts of the body, or even to somebody else. It is critical that the area remain covered, that old dressing be discarded in an appropriate manner and that hands be washed immediately upon any contact. Routine Band-Aids are not an acceptable option. The vaccination team will recommend special occlusive medical dressings.

The CDC recommends:

• Sterile gauze loosely held down by tape
• Perforated plastic bubble
• Semi permeable membrane occlusive dressing

Under no circumstances should the vaccination site be rubbed or scratched to help prevent problems at the inoculation site or spread of the virus to other sites or individuals.

Can I get smallpox from someone who has been vaccinated?

No, but you can get cowpox, at least locally only from coming into direct contact with the vaccination site. Cowpox can cause a rash, fevers and flu-like myalgias and headache. Cowpox is not spread through breathing, coughing or sneezing by vaccinated patients.

What will happen after the vaccination?

A successful vaccination will result in a raised, red itchy bump within about 4 days. Over the first week post-vaccination, pus-filled blisters will form. It is natural for these blisters to drain. Over the second week, the blisters form into scabs. When the scab falls off, a scar may be present.

Out of a recent group of 1500 volunteers vaccinated for smallpox, 30 percent also experienced localized swelling of the vaccination site accompanied by tenderness. Lymph nodes may become swollen.

Seventeen percent of this test group also experienced low-grade fevers (around 101 degrees Fahrenheit), generalized flu-like symptoms and significant vaccination site discomfort. Between 1 and 2 percent of vaccinated individuals ran fevers of 102 degrees or higher.

What are the risks of the vaccination?

More concerning potential side effects to the smallpox vaccination include a severe generalized rash (Erythema multiforme); localized necrosis of the skin (large, deep sore); encephalitis, accidental spread of the virus to other body areas or to other individuals; eczema vaccinatum, corneal scarring (from physical transfer of the virus to the eyes); generalized vaccinia (known as progressive vaccinia); fetal vaccinia and death.

According to old statistics from the 1960s, it is estimated that 1-2 vaccinated patients per 1 million may die as a result of the vaccine. The makeup of our nation in terms of health concerns has drastically changed in the past 30 plus years. We now have 2-3 times more eczema/atopic patients (roughly 10-15% of the entire country) than we did then. AIDS, organ transplant patients and many forms of chemotherapy were unheard of then. All of these individuals stand a higher risk of more severe side effects associated with the vaccine. It is likely that undiagnosed eczema patients or those with unknown immunodeficiency disorders may receive the vaccine and the numbers of vaccine-associated deaths may be higher.

I was vaccinated prior to 1972. Do I still need the vaccine?

Yes. Full protection of the vaccine only lasts 10 years. While it is likely that some antibodies remain, it is not yet known if past vaccinations offer any true protection during a smallpox epidemic.

Previously vaccinated individuals may experience less of a localized reaction or potential side effects to a repeat vaccination than those being vaccinated for the first time.

Can pregnant women receive the vaccine?

No. The vaccine may result in the fetus developing the infection that often results in death of the fetus or newborn, at least within the third trimester. It is suspected that early pregnancies may result in miscarriage as a result of vaccination during this time. For these reasons, the use of the vaccine in a non-emergent setting is not recommended. In the scenario of a smallpox epidemic, the risk to the mother of acquiring smallpox may outweigh the risk to the fetus and the vaccine may be given after discussion with a physician.

Pregnancy should not occur within one month of receiving the vaccination.

Vaccinated individuals should be very careful not to come into contact with a pregnant woman. The virus can be transferred and result in the same fetal concerns.

Who is going to receive the vaccine?

At this time, the vaccine is mandatory for the military and being offered to 500,000 first responders (healthcare workers most likely to come into contact with smallpox patients) as well as to U.S. embassy employees located in the Middle East.

A larger pool of an estimated 10 million emergency workers, police and healthcare workers will next be offered the vaccine, although there is no current time frame for this. Individual state health departments are in charge of the vaccination process as well as planning time frames.

Dryvax is categorized as an investigational drug. It is not available in physician's offices. Those in the public who wish to receive the vaccine can either enroll now in a handful of ongoing studies across the country or will be able to enroll in an investigational study available in their state once the Department of Health and Human Services has completed developing a protocol. This is expected sometime by summer of 2003.

An expanded vaccination offering to the public is expected sometime in 2004 once the new vaccine is licensed.

Who Should Not Receive The Smallpox Vaccine

• Pregnant or nursing women
• Infants and Children

  While the vaccine is not recommended for children 12 months and under, the vaccine is currently not going to be offered non-emergently to anyone under the age of 18.

• Immunosuppressed Individuals

  Cancer

  HIV/AIDS
  Topical Steroid Use
  Oral Steroid
  Inhaled Steroid Use
  Protopic or Elidel Use
  Chemotherapy Use
  Organ or Tissue Transplant
  Other Immunosuppressive Therapies
• Those With Active Skin Disorders

  Acne

  Any Open Wounds
  Burns
  Eczema
  Psoriasis
  Current Contact Dermatitis
  Open Or Healing Surgical Excisions

  Open skin wounds may become more easily infected with the vaccinia virus shed from the vaccination site. Also, even eczema patients with a past history of this condition risk a severe reaction known as eczema vaccinatum. Eczema patients should avoid contact with anyone who has recently has the vaccine.

• Allergy To Vaccine Ingredients

  This again includes:

  Chlortetracycline Hydrochloride
  Neomycin Sulfate
  Polymyxin B Sulfate
  Streptomycin Sulfate
• Eye Disease

  Conjunctival or Corneal Disorders Including: Infections, Abrasions And Inflammations

  Active eye disease may cause patients to have itching and want to rub their eyes. This may result in a transfer of the virus from the vaccination site. Vaccinia keratitis may result in permanent visual problems or even blindness.

Anyone who is at higher risk in these categories should avoid newly vaccinated individuals!

As you can see, the smallpox vaccine is not the garden variety vaccination we are used to. For now it makes sense to make prudent use of the vaccine where it offers the most protection, increases the overall immunity of our country, and ultimately makes the use of bioterrorism less likely.

Smallpox images courtesy of the CDC Public Health Image Library. Reproduction of these images is strictly prohibited.

Audrey Kunin, M.D.

(Any topic discussed in this article is not intended as medical advice. If you have a medical concern, please check with your doctor.)

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