Editor’s note: This is the first of three parts of a commentary on the benefits and risks of the nation’s smallpox vaccination plan.

I am a dermatologist, and in the 1960s and ’70s during my training and days at Massachusetts General Hospital as an instructor in dermatology, I saw the complications of smallpox vaccination. I have been following the development and implication of the recent program for smallpox vaccination and I feel the program is opening a Pandora’s box, and unfortunately we find a Medusa head in the box – pardon my mixed myths.

The fundamental questions relate to the relative risks of a bioterrorism attack with smallpox vs. the risks of complications of vaccination. The risk of a smallpox attack seems to have been judged differently at different times by the government – from “possibly imminent,” “imminent,” “possible in a war,” and “possible” to now perhaps “unknown.” The likelihood of a smallpox attack cannot be judged by the data available at this time. The risks of vaccination and its complications – the medical, legal and socioeconomic complications – are receiving more scrutiny and will be significant factors to be considered if the program is to progress.

The known complications to individuals who receive the live vaccine have been outlined by numerous articles in the media and can be examined in detail at www.bt.cdc.gov. The Centers for Disease Control and Prevention (CDC) has done an excellent job in gathering all types of data and the site is extremely helpful. The vivid photographs of complications will give any volunteers second thoughts about receiving the vaccine.

For an individual who has never received the vaccine a primary take can be expected – a painful local vesicular (blister) lesion that slowly heals in two weeks or so. For those who have had previous vaccination (like President Bush and me and a whole host of older Americans) a secondary take will most likely occur, i.e. minimal blister formation and no real morbidity. This milder take is thought to reflect persistent and continued immunity to smallpox; the degree of immunity varies considerably, but decent immunity may be absent in previously vaccinated persons.

But now what about complications? For first-timers, those who have never been vaccinated, the complications that arise are many and varied. Nearly all the most common ones create no great morbidity, but they can include a severe primary take with marked vesicle formation, swelling, pain, difficulty in moving the arm and streaks of lymphangitis (those streaks of red that move up the arm to the lymph nodes, commonly called “blood poisoning” but in this case may reflect a viral, not a bacterial etiology). There are also so-called allergic reactions – not uncommon in my experience – focal and widespread hives, and a skin eruption called erythema multiforme, i.e. extensive hive-like lesions that develops blisters.

One of the more severe complications is vaccina. The virus is thought to be “in the blood” and blisters appear all over the body. The patient is toxic, sick and may die of this untoward reaction. Very rarely in other patients the original site does not heal and it even progresses with mark necrosis of the underlying skin and deeper tissues. A rare and often fatal encephalitis may develop as a complication of smallpox vaccination. There is no way to predict who might develop these complications. Vaccinia can be treated with a special form of gamma globulin (vaccinia immune globulin or VIG) that contains antibodies to the vaccinia virus.

Dr. John Modin, the chairman of the Advisory Committee on Immunization Practice, feels skeptical that VIG works since there has never been a rigorously controlled study of its effectiveness. There is no effective treatment for encephalitis, although certain newer anti-viral compounds may play a role in therapy So what are the chances of these complications occurring? Various numbers have been cited; some based upon studies done in 1968. The number after the diagnosis are cases per million of first-time vaccination: vaccinial encephalitis, 2.9; vaccinia necrosum, 0.9; eczema vaccinatum, 10.4; generalized vaccinia, 23.4; accidental autoinoculation, 25.4; deaths, 1.1.

One in a thousand, one in a million. Pick a number. It doesn’t matter – complications happen. If encephalitis occurs in one in a million that does not mean one has to vaccinate a million people in order for that to occur. It could occur after 25 or 1,000 individuals were vaccinated. I stress this point because statistics can give a false sense of security. The program developed by the CDC and the U.S. Public Health Service recognizes these complications and carefully outlines them in numerous publications.

It is tricky to consider all these various types of complications as they might arise in unvaccinated members of the community who might come in contact with a recently vaccinated individual. An unvaccinated individual in the community can develop the same complications, yet the primary takes may develop in atypical locations such as the eye (causing blindness), fingers, genitalia and other sites. An individual with a “normal immune status” might handle or control these complications without difficulty – but remember encephalitis can occur in anyone.

But the immunocompromised person and certain other individuals may develop any and all of these complications to a much greater degree. There are thousands and thousands of immunocompromised and at-risk individuals in the community.

Of particular interest to the dermatologist are patients with atopic dermatitis (eczema), Darier’s disease, severe acne (on or off Accutane), and other conditions where the normal barrier of the skin is impaired. What dermatologists saw years ago was extensive vaccinia on the inflamed (and even uninflammed) skin of patients with active and inactive atopic dermatitis (eczema); presenting as widespread, small and large blisters which eroded and became secondarily infected with bacteria: a terrible and frightening condition.

In addition to patients with certain skin diseases other individuals at risk include renal transplant patients, patients with HIV-AIDS (diagnosed and undiagnosed), lymphoma and leukemia patients, pregnant women, patients on chemotherapy, patients on high doses of corticostreoids, patients with lupus and other so-called auto-immune diseases, as well as other patients with various conditions. The vaccine uses a live virus (unlike other vaccines) and the site of inoculation is contagious. The vaccinia virus is not the smallpox virus: one should recall the original vaccinations by Dr. Joseph Lister were the cowpox virus harvested from the teats of cows.

The CDC suggests covering the vaccination sites with gauze to minimize the contagious nature of the site, but no data I know of demonstrates that this precaution will do what it proposes to do or hopes to accomplish. These dressings may need to be changed daily and the take monitored in all health care workers who receive the vaccine early on in the program.

William Gallagher, M.D., is a Bangor dermatologist. He is a member of the American Academy of Dermatology.