Bruce G. Gellin

BACKGROUND: Immunization may now be undervalued because vaccines have largely eliminated the threat of serious infectious diseases in childhood. As the incidence of vaccine-preventable diseases has declined, concern about vaccine safety has increased. Significant erosion of public confidence in vaccine safety could lead to reduced immunization rates and a resurgence of vaccine-preventable diseases. OBJECTIVE AND METHODS: To assess parents' understanding of vaccine-preventable diseases, vaccines, immunization practices, and policies, we conducted a telephone survey in the United States with a nationally representative sample (n = 1600) of parents with children </=6 years of age, and expectant parents in April and May 1999. RESULTS: Eighty-seven percent of respondents deemed immunization an extremely important action that parents can take to keep their children well. Although respondents' overall rating of immunization safety was high, a substantial minority held important misconceptions. For example, 25% believed that their child's immune system could become weakened as a result of too many immunizations, and 23% believed that children get more immunizations than are good for them. Children's health care providers were cited as the most important source of information on immunizations. CONCLUSIONS: Although the majority of parents understand the benefits of immunization and support its use, many parents have important misconceptions that could erode their confidence in vaccines. A systematic educational effort addressing common misconceptions is needed to ensure informed immunization decision-making. Physicians, nurses, and other providers of primary care have a unique opportunity to educate parents because parents see them as the most important source of information about immunizations.vaccination, immunization, pediatric, safety, health beliefs.

<i>LISTERIA monocytogenes</i>has been recognized as a human pathogen for more than 50 years; it causes illness mainly in pregnant women, newborns, elderly persons, and immunocompromised persons. The organism is found in multiple ecological sites and throughout the food chain, and anecdotal reports have linked human illness with the ingestion of foods contaminated with<i>Listeria</i>.¹More recently, it has been shown to cause outbreaks of illness that were associated with commercial food products.^2-5The Food and Drug Administration has recommended product recalls when<i>L monocytogenes</i>has been identified in commercial foods that are available for consumption without further cooking. Although recalls have generated widespread public concern, information about the magnitude of risk and the clinical presentations of disease has not been widely available to the medical community. This article reviews the history, microbiology, ecology, pathogenesis, epidemiology, and clinical spectrum of human illnesses caused by<i>L monocytogenes</i>and highlights

The lifetime risk of human papillomavirus (HPV) infection exceeds 50%. HPV infection causes >550,000 cases of cervical and anogenital cancer worldwide annually. Infection also causes precancerous lesions and genital warts. HPV types 16 and 18 cause approximately 70% of HPV-related cancers, and HPV types 6 and 11 cause approximately 90% of cases of genital warts. A quadrivalent vaccine for HPV types 6, 11, 16, and 18 (HPV 6/11/16/18) has been developed for prevention of cervical cancer, genital warts, and vulvar and vaginal precancerous lesions. Prophylactic vaccination of young women was 96%-100% effective in preventing HPV 6/11/16/18-related cervical and anogenital precancers and genital warts. Efficacy remained high for at least 5 years following vaccination. Postvaccination anti-HPV levels in adolescents were superior to those observed in women (the population in which efficacy was shown). Vaccination was generally well tolerated. The vaccine is licensed in >80 countries. It has been added to national vaccination programs, including that of the United States. Widespread use of HPV 6/11/16/18 vaccine is expected to greatly reduce the incidence of HPV-related cancers, precancers, and genital warts.

Recent surveys found that an increasing number of parents are concerned that infants receive too many vaccines. Implicit in this concern is that the infant's immune system is inadequately developed to handle vaccines safely or that multiple vaccines may overwhelm the immune system. In this review, we will examine the following: 1) the ontogeny of the active immune response and the ability of neonates and young infants to respond to vaccines; 2) the theoretic capacity of an infant's immune system; 3) data that demonstrate that mild or moderate illness does not interfere with an infant's ability to generate protective immune responses to vaccines; 4) how infants respond to vaccines given in combination compared with the same vaccines given separately; 5) data showing that vaccinated children are not more likely to develop infections with other pathogens than unvaccinated children; and 6) the fact that infants actually encounter fewer antigens in vaccines today than they did 40 or 100 years ago.

To determine the morbidity and mortality due to listeriosis in the United States, the authors undertook an active surveillance project in 1986 to identify all cases in which Listeria monocytogenes was isolated from cultures of ordinarily sterile sites in a population of 34 million persons. The authors estimated that at least 1,700 cases of listeriosis and 450 deaths occurred in the United States in 1986; 27% of these cases occurred in pregnant women, with 22% of perinatal cases resulting in stillbirths or neonatal deaths. The risk of listeriosis in adults (0.5 per 100,000 population) was similar in all regions studied; the incidence of perinatal listeriosis was three times higher in Los Angeles County, California, than in the other areas (24.3/100,000 live births vs. 7.8/100,000 live births). Geographic variation may have resulted from underdiagnosis of perinatal listeriosis in five of the study areas. Multilocus electrophoretic enzyme typing was useful for elucidating the molecular epidemiology of L. monocytogenes; perinatal listeriosis was significantly associated with one group of related strains. Multilocus electrophoretic enzyme typing also identified three clusters representing possible common-source outbreaks. These findings document the substantial morbidity due to listeriosis in the United States; to the extent that sporadic listeriosis is foodborne, this morbidity could be reduced by appropriate preventive measures, particularly in persons known to be at increased risk of infection.