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Objectives. We described seroprevalence of antibody to hepatitis A virus (anti-HAV) in the United States during 1999–2006 and compared it with seroprevalence before the availability of vaccine.Methods. We analyzed data from the 1988–1994 and 1999–2006 National Health and Nutrition Examination Survey (NHANES) to obtain estimates of anti-HAV seroprevalence for the U.S. household population. We grouped region of residence based on the 1999 Advisory Committee on Immunization Practices recommendations into 17 states with any recommendation (vaccinating) and 33 states without any recommendation (non-vaccinating).Results. During 1999–2006, the overall seroprevalence of anti-HAV was 34.9% (95% confidence interval [CI] 33.1, 36.7). During 1999–2006, U.S.-born children living in vaccinating states (33.8%, 95% CI 26.2, 42.2) had a higher seroprevalence than children in non-vaccinating states (11.0%, 95% CI 9.4, 12.8; p<0.001). Seroprevalence among children increased from 8.0% (95% CI 6.3, 10.1) during 1988–1994 to 20.2% (95% CI 16.0, 24.8) during 1999–2006 (p<0.001). For U.S.-born children aged 6–19 years, the strongest factor associated with seroprevalence was residence in vaccinating states. Among U.S.-born adults aged >19 years, the overall age-adjusted seroprevalence of anti-HAV was 29.9% (95% CI 28.3, 31.5) during 1999–2006, which was not significantly different from the seroprevalence during 1988–1994 (32.2%, 95% CI 30.1, 34.4).Conclusions. Increases in seroprevalence among children in vaccinating states suggest a positive effect of the 1999 vaccination recommendations.

Objective. We estimated the varicella seroprevalence among the U.S. population aged 6–49 years based on retested National Health and Nutrition Examination Survey (NHANES) specimens collected between 1999 and 2004—originally tested using a method unsuitable for detecting vaccine-induced immunity—and compared it with historical estimates.Methods. We performed a confirmatory test suitable for detecting vaccine-induced immunity on all available specimens from 6- to 19-year-olds who originally tested negative (n=633), and on 297 randomly selected specimens that had tested positive. Retest results superseded original results for determining seroprevalence. We assessed seroprevalence for the entire sample aged 6–49 years (n=16,050) by participant demographic characteristics and compared it with historical estimates (NHANES 1988–1994).Results. The percentage of false-negative results for the original test was higher for specimens from younger children (6–11 years of age: 27.5%; 12–19 years of age: 13.3%) and for specimens collected most recently (2001–2004: 26.0%; 1999–2000: 12.6%). The age-adjusted rate of varicella seroprevalence for 1999–2004 was 93.6% for 6- to 19-year-olds and 98.0% for adults aged 20–49 years compared with 90.0% and 98.1%, respectively, for 1988–1994. We found an increase in seropositivity between the survey periods, from 93.2% to 97.2% (p<0.001) among 12- to 19-year-olds. For children, non-Hispanic black ethnicity and younger age were associated with lower seroprevalence in both survey periods.Conclusions. Varicella seroprevalence increased with age among children and was uniformly high in the U.S. adult population between 1999 and 2004. The original testing produced false-negative seroprevalence results among children's specimens collected between 1999 and 2004 from 6- to 19-year-olds.

Purpose: The study determines the consent rates for storage of biologic samples for future research with and without genetic studies and describes trends in sociodemographic factors associated with consent.Methods: We performed an analysis of the characteristics of consenting individuals participating in three data cycles of the National Health and Nutrition Examination Survey, a nationally representative survey of the U.S. population.Results: In the 1999 to 2000 and the 2001 and 2002 surveys, 84.8% and 90.1% of eligible participants, respectively, consented to have their biologic samples including DNA stored in a national repository. Female and non-Hispanic black participants were least likely to consent when genetic studies and DNA were included. In the 2003 to 2004 survey, with the discontinuation of the DNA collection, 98.4% signed the consent document and these race/gender differences were no longer observed.Conclusion: Females and non-Hispanic blacks consistently had lower consent rates during the survey years when genetic studies were mentioned in the consent, but once DNA collection was discontinued these differences disappeared. These findings demonstrate wide acceptance among survey participants for allowing storage of specimens for future studies but indicate the need to explore race/gender issues with the collection and storage of DNA for genetic research.

Purpose: To determine the sociodemographic factors associated with consent for storage of DNA for future genetic research.Methods: Analysis of the characteristics of consenting individuals participating in the National Health and Nutrition Examination Survey, a nationally representative survey of the US household population.Results: In 1999, 84% (95% confidence interval 82.4–85.6) of eligible participants consented to have their blood samples included in a national repository for genetic research. In 2000, 85.3% (95% confidence interval 84.0–86.6) consented. Females and black participants in both years were least likely to consent (1999, 82.2% and 73.2%; 2000, 83.6% and 81.3%, respectively). An assessment by logistic regression demonstrated that in both years only non-Hispanic black race/ethnicity was a significant independent predictor for not consenting to future genetic research.Conclusion: Although non-Hispanic black individuals have overall response rates similar to those of the other racial/ethnic groups, they are less likely to agree to have a blood sample saved for future genetic research. In balance, however, these findings demonstrate wide acceptance among survey participants for allowing storage of specimens for future genetic research across many demographic variables.

At the time of varicella vaccine introduction in the United States, an estimated 4 million episodes of varicella occurred annually. This survey of varicella seroprevalence is the first to describe immunity to a vaccine‐preventable disease prior to vaccine introduction in the United States population. The objective of this analysis is to describe patterns of naturally‐acquired varicella and understand characteristics associated with infection in the varicella vaccine–naive United States population. A nationally representative cross‐sectional health examination survey that included venipuncture was conducted among 21,288 U.S. participants aged 6 years and older from 1988 through 1994. Serologic evidence of varicella‐zoster virus infection was measured by enzyme immunoassay of varicella‐zoster virus‐specific IgG antibody. The seroprevalence of IgG antibody to varicella‐zoster virus increased from 86.0% in children aged 6 through 11 years to 99.6% in adults aged 40 through 49 years. Immunity to varicella remained at 99% or higher in Americans aged 50 years and older. Among persons aged 6 through 19 years, non‐Hispanic black children were 40% less likely to be seropositive compared with white children (odds ratio [OR], 0.6; 95% confidence interval [CI], 0.4–0.8). Among young adults aged 20 through 39 years, women with a history of live birth (OR, 4.3; 95% CI, 2.1–8.7) and married men (OR, 2.7; 95% CI, 1.2–5.7) were more likely to have naturally‐acquired immunity to varicella. This study found that, prior to use of varicella vaccine in the United States, age, race, and marital characteristics were independently associated with naturally acquired varicella. Future varicella serosurveys in Americans will provide essential information to interpret the population impact of varicella vaccine. J. Med. Virol. 70:S111–S118, 2003. © 2003 Wiley‐Liss, Inc.

At the time of varicella vaccine introduction in the United States, an estimated 4 million episodes of varicella occurred annually. This survey of varicella seroprevalence is the first to describe immunity to a vaccine-preventable disease prior to vaccine introduction in the United States population. The objective of this analysis is to describe patterns of naturally-acquired varicella and understand characteristics associated with infection in the varicella vaccine–naive United States population. A nationally representative cross-sectional health examination survey that included venipuncture was conducted among 21,288 U.S. participants aged 6 years and older from 1988 through 1994. Serologic evidence of varicella-zoster virus infection was measured by enzyme immunoassay of varicella-zoster virus-specific IgG antibody. The seroprevalence of IgG antibody to varicella-zoster virus increased from 86.0% in children aged 6 through 11 years to 99.6% in adults aged 40 through 49 years. Immunity to varicella remained at 99% or higher in Americans aged 50 years and older. Among persons aged 6 through 19 years, non-Hispanic black children were 40% less likely to be seropositive compared with white children (odds ratio [OR], 0.6; 95% confidence interval [CI], 0.4–0.8). Among young adults aged 20 through 39 years, women with a history of live birth (OR, 4.3; 95% CI, 2.1–8.7) and married men (OR, 2.7; 95% CI, 1.2–5.7) were more likely to have naturally-acquired immunity to varicella. This study found that, prior to use of varicella vaccine in the United States, age, race, and marital characteristics were independently associated with naturally acquired varicella. Future varicella serosurveys in Americans will provide essential information to interpret the population impact of varicella vaccine. J. Med. Virol. 70:S111–S118, 2003. © 2003 Wiley-Liss, Inc.

Purpose: To determine the sociodemographic factors associated with consent for storage of DNA for future genetic research.

The design of the laboratory component of a mobile examination survey such as the National Health and Nutrition Examination Survey requires that the physical limitation of the mobile examination center be balanced against the requirements of the laboratory analyses needed to fulfill the goals of the survey. In order to include an analysis in the survey, the scientific merit of the laboratory test must be established and a consensus must be reached on the appropriateness of the technology for the six years of the survey. The public health importance of the analysis and the subsequent results are also evaluated before inclusion into the laboratory protocol. Finally, the feasibility of incorporating the analysis into the protocol is reviewed. The laboratory component of NHANES III is discussed, addressing these points with descriptions of the reasons for inclusion and exclusion of key analytes.

This study was conducted to determine the level of seropositivity to diphtheria and tetanus among women in the United States, and to investigate whether the recommendation of the Advisory Committee on Immunization Practices that adolescents and adults receive a booster vaccine for diphtheria and tetanus every 10 years after primary childhood immunization is practiced by the physicians who regularly care for women. Analyses were made using data from the third National Health and Nutrition Examination Survey (NHANES III; 1988-1994). This survey provided extensive demographic information gathered from personal interviews and clinical data collected by physical examinations performed in special mobile examination centers located throughout the United States. Among the 16,123 female participants, sera samples from 9411 females 6 years of age or older were available to test for antibodies to diphtheria and tetanus. Among all participants, 57% were seropositive for diphtheria, 64% for tetanus, and 48% for both. The percentages of women immune to diphtheria decreased with increasing age so that only 27% of women 60 years old or older had diphtheria seropositivity. The same trend was seen for tetanus, with only 23% of women having immunity at 60 years of age or older, but seropositivity to tetanus remained at 80% or greater until after 39 years of age. Immunity to both diphtheria and tetanus was greatest among young girls, age 6 to 11 years. No differences in diphtheria seropositivity were seen among different racial or ethnic groups (non-Hispanic white women, non-Hispanic black women, and Mexican Americans) in the youngest age interval, 6 to 11 years, or in the group aged 50 to 59 years. The highest seropositivity to diphtheria was seen in non-Hispanic white women aged 30 to 39 years; however, by age 50, non-Hispanic white women had the lowest immunity of all racial/ethnic groups. Mexican Americans were the only racial or ethnic group that had sufficient numbers to compare the seropositivity of women born in the United States with those born elsewhere. Mexican American women of childbearing age born outside the United States had significantly lower immunity to diphtheria than other racial or ethnic populations (P<0.01 for all age groups except 40-49 years, which had a Pvalue of 0.07). These patterns were repeated for tetanus seropositivity. The lowest immunity to tetanus was seen in Mexican Americans aged 20 to 59 years who were born outside the United States (P<0.001). An age-adjusted univariate analysis was conducted of possible variables related to seropositivity for both diphtheria and tetanus, including sociodemographic and healthcare access across each racial or ethnic group. Birth outside the United States continued to be a significant risk factor for lower immunity to diphtheria and tetanus for Mexican American women (P<0.001 for both). Also, among Mexican American women, but not among other racial or ethnic groups, being at or above the poverty level and having access to regular health care were associated with higher levels of seropositivity. In general, immunity levels increased as levels of education increased, regardless of racial/ethnic group. For non-Hispanic white women and Mexican American women, nulliparous women had higher levels of seropositivity than those with 2 or more live births. Multivariate modeling adjusting for age, race/ethnicity, and foreign birth found higher education to have the highest association with higher seropositivity for all women and for non-Hispanic white women. Birth outside the United States, living below the poverty level, and low levels of education were predictors of low immunity to diphtheria and tetanus among Mexican American women. There were no unique predictive factors for non-Hispanic black women.

Precise estimates of the incidence of hepatitis B virus (HBV) infection are required to assess the impact of immunization and other prevention strategies in the United States. Race- and age-specific prevalence data obtained from the second and third National Health and Nutrition Examination Surveys (NHANES II, 1976–1980, and NHANES III, 1988–1994) were used to estimate the annual incidence of HBV infection by catalytic modeling. During the period covered by NHANES II, an estimated 323,462 persons were infected annually, and 334,863 were infected annually during the period covered by NHANES III. No statistically significant declines in prevalence of HBV infection occurred between the two surveys, a period during which hepatitis B vaccination targeted only limited numbers of high-risk adults.

To provide more accurate estimates of Helicobacter pylori infection in the US population, IgGantibody levels were measured in serum from 2581 persons aged 6–19 years examined during phase1 of the third National Health and Nutrition Examination Survey. Overall, 24.8% of participantshad evidence of H. pylori infection. Infection was strongly associated with increasing age (X2trend, P < .01) and being nonwhite (17.0% of non-Hispanic whites vs. 40.1% of non-Hispanic blacks and 42.0% of Mexican Americans infected). In a multivariate logistic regression model, H. pylori infection was significantly associated with increasing age (odds ratio [OR] = 1.07/year), being nonwhite (non-Hispanic black OR = 2.6 or Mexican American OR = 1.8), poverty (OR = 1.5), crowding (OR = 5.6), and- head of household education level (OR = 1.8). In Mexican Americans, infection was associated with birth outside the United States or Canada in the univariate analyses but was not significantly associated after adjustment for age, poverty, crowding, and head of household education level.