Responses to Dilutions of Smallpox Vaccine

In a randomized, single-blind study, 680 healthy, previously unvaccinated adults were inoculated intradermally with undiluted vaccinia virus vaccine, a 1:5 dilution, or a 1:10 dilution. The success rates were similarly high in all three groups: 97.2 percent, 99.1 percent, and 97.1 percent, respectively. Local and systemic symptoms were common, and 14 percent of subjects had rash at another site, including erythema multiforme in two subjects.

The data from this large study show that the limited supply of smallpox vaccine can be diluted 1:10 and still induce an immune response in about 97 percent of healthy, younger adults. Of the 15 subjects who had no response to the initial vaccination, 6 had preexisting neutralizing antibodies, suggesting previous exposure to vaccinia virus.

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Dose Effects of Smallpox Vaccine

The administration of undiluted vaccinia vaccine led to vesicle formation in 19 of 20 healthy volunteers. With a 1:10 dilution, the success rate was 70 percent. With a 1:100 dilution the success rate was only 15 percent. The appearance of vaccinia vesicles correlated well with vigorous cytotoxic T-cell responses and with interferon- T-cell responses.

This study documents that the vaccinia vaccine produced in 1982 still has excellent potency but that dilution decreases the success rate. The formation of a vesicular skin lesion is an excellent indicator of the development of a protective immune response.

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Pulmonary Dead Space and Mortality in the Acute Respiratory Distress Syndrome

Pulmonary dead space, the fraction of ventilation that is wasted, is greater than normal in patients with the acute respiratory distress syndrome who are undergoing mechanical ventilation. This study found that when the dead-space fraction was measured early in the course of the syndrome, higher values were independently associated with an increased risk of death.

The cause of the elevated dead-space fraction in these patients is unknown, but it may reflect pulmonary vascular injury. The dead-space fraction, which can be measured at the bedside, could be used to identify patients at a particularly high risk of death.

Special Article: For-Profit and Nonprofit Health Maintenance Organizations

There is some concern about whether medical care of similar quality is offered by for-profit and nonprofit health maintenance organizations (HMOs). This study analyzed assessments of medical care by enrollees in for-profit and nonprofit HMOs. It found that although there were few overall differences, for-profit HMOs were rated less favorably than nonprofit HMOs by patients with self-reported fair or poor health.

In large part, these findings reflect differences in the perceptions of care. The study did not include objective indicators of clinical quality or patient outcomes. Thus, it cannot provide information about whether patients who are in poor health are actually more or less likely to receive good medical care through nonprofit or for-profit HMOs.

Clinical Practice: Peanut Allergy

A 19-year-old woman is brought to the emergency room because of the acute onset of dyspnea, wheezing, vomiting, and generalized flushing. She has well-controlled asthma as well as a history of atopic dermatitis as an infant and urticaria after ingesting peanut butter at the age of five years. According to friends she ate a chocolate-chip cookie from a vending machine just before her symptoms developed. The ingredients listed on the cookie wrapper do not include peanuts. Nevertheless, how should this patient's condition be treated?

This article reviews the diagnosis and management of peanut allergy, which accounts for the majority of fatal and near-fatal anaphylactic reactions in the United States.

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Current Concepts: Diagnosis and Management of Smallpox

In 1980, smallpox was declared to have been eradicated, but some laboratories retained the variola virus. Because of the possibility of bioterrorism or even an accidental release, physicians need to be aware of the essential clinical facts about this highly infectious viral disease. Two experts summarize the clinical manifestations, epidemiologic features, and treatment of smallpox, including guidelines for use of the vaccine.

Legal Issues in Medicine: Bioterrorism, Public Health, and Civil Liberties

In the wake of the September 11, 2001, terrorist attacks, the Centers for Disease Control and Prevention proposed a model act for the states that specifies steps to be taken to contain an epidemic resulting from a bioterrorist attack. The act would grant broad powers to the states in the event of public health emergencies arising from bioterrorism. Annas discusses the trade-off between civil liberties and the need to protect the health of the public in the event of bioterrorism. His underlying premise is that the model act, despite being revised in December 2001, goes too far.

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