SARS-CoV-2 Serology and Self-Reported Infection Among Adults - National Health and Nutrition Examination Survey, United States, August 2021-May 2022.

CDC COVID-19 surveillance systems monitor SARS-CoV-2 antibody prevalence to collect information about asymptomatic, undiagnosed, and unreported disease using national convenience samples of blood donor data from commercial laboratories (1,2). However, nonrandom sampling of data from these systems could affect prevalence estimates (1-3). The National Health and Nutrition Examination Survey (NHANES) collects SARS-CoV-2 serology data among a sample of the general U.S. civilian population (4). In addition, NHANES collects self-reported COVID-19 vaccination and disease history, and its statistical sampling design is not based on health care access or blood donation. Therefore, NHANES data can be used to better quantify asymptomatic SARS-CoV-2 infection prevalence and seropositivity attained through infection without vaccination. Preliminary NHANES 2021-2022 results indicated that 41.6% of adults aged ≥18 years had serology indicative of past infection and that 43.7% of these adults, including 57.1% of non-Hispanic Black or African American (Black) adults, reported never having had COVID-19, possibly representing asymptomatic infection. In addition, 25.5% of adults whose serology indicated past infection reported never having received COVID-19 vaccination. Prevalences of seropositivity in the absence of vaccination were higher among younger adults and Black adults, reflecting the lower observed vaccination rates among these groups (5). These findings raise health equity concerns given the disparities observed in SARS-CoV-2 infection and COVID-19 vaccination. Results from NHANES 2021-2022 can guide ongoing efforts to achieve vaccine equity in COVID-19 primary vaccination series and booster dose coverage.

Prevalence of Urogenital Mycoplasma genitalium Infection, United States, 2017 to 2018.

ABSTRACT: During the 2017-2018 National Health and Nutrition Examination Survey, urine samples from participants aged 14 to 59 years were tested for Mycoplasma genitalium infection. Overall prevalence was 1.7% (95% confidence interval [CI], 1.1%-2.7%). Prevalence was similar between males (1.8% [95% CI, 0.9%-3.1%]) and females (1.7% [95% CI, 0.8%-3.0%]).

Seroprevalence of Antibodies to Toxocara Species in the United States and Associated Risk Factors, 2011-2014.

Background: Toxocariasis results from infection with larval stages of a dog and cat intestinal nematode and causes human morbidity. The current United States estimate of Toxocara exposure is 13.9% (National Health and Nutrition Examination Survey [NHANES] III [1988-1994]). Methods: We used a multiplex bead-based assay (Tc-CTL-1MBA) with purified Toxocara canis antigen to estimate Toxocara antibody seroprevalence in serum of 13 509 persons aged ≥6 years from NHANES 2011-2014 and identified seropositivity risk factors. We tested a subset of 500 samples with the T. canis enzyme immunoassay used in NHANES III to estimate prior seroprevalence had samples from NHANES III been tested by Tc-CTL-1MBA. Results: The age-standardized estimate of Toxocara seroprevalence was 5.0% (95% confidence interval [CI], 4.2%-5.8%), lower than previously reported even after adjusting for increased Tc-CTL-1MBA specificity. Risk factors for seropositivity from multiple logistic regression were older age, non-Hispanic black/Hispanic origin, male sex, living below poverty level, households with ≥0.5 persons per room, less than college education, and birth outside of the United States. Conclusions: Toxocara seroprevalence estimates in 2011-2014 were lower than in a study from NHANES III (1988-1994), but seropositivity risk factors remained the same and should continue to be the focus of prevention efforts.

National Center for Health Statistics Guidelines for Analysis of Trends.

Many reports present analyses of trends over time based on multiple years of data from National Center for Health Statistics (NCHS) surveys and the National Vital Statistics System (NVSS). Trend analyses of NCHS data involve analytic choices that can lead to different conclusions about the trends. This report discusses issues that should be considered when conducting a time trend analysis using NCHS data and presents guidelines for making trend analysis choices. Trend analysis issues discussed include: choosing the observed time points to include in the analysis, considerations for survey data and vital records data (record level and aggregated), a general approach for conducting trend analyses, assorted other analytic issues, and joinpoint regression. This report provides 12 guidelines for trend analyses, examples of analyses using NCHS survey and vital records data, statistical details for some analysis issues, and SAS and SUDAAN code for specification of joinpoint regression models. Several an lytic choices must be made during the course of a trend analysis, and the choices made can affect the results. This report highlights the strengths and limitations of different choices and presents guidelines for making some of these choices. While this report focuses on time trend analyses, the issues discussed and guidelines presented are applicable to trend analyses involving other ordinal and interval variables.

National Health and Nutrition Examination Survey: California and Los Angeles County, Estimation Methods and Analytic Considerations, 1999-2006 and 2007-2014.

Background California is the most populated state and Los Angeles County is the most populated county in the United States. National Health and Nutrition Examination Survey (NHANES) sample weights and variance units were developed for these places to obtain subnational estimates. Objective This report describes the California and Los Angeles County NHANES 1999-2006 and 2007-2014 samples, including the creation of the sample weights and variance units and descriptions of the resulting data files. Some analytic guidelines are provided. Results Eight years of NHANES data were combined for each data file to provide an adequate sample size and reduce disclosure risks. Because Los Angeles County has been a self-representing primary sampling unit, sample weights for Los Angeles County were relatively straightforward. However, a modelbased approach was used to create sample weights for California. The relatively large proportion of Mexican- American and other Hispanic persons in California, coupled with the different NHANES 1999-2014 sample design requirements for oversampling these groups within the small number of NHANES locations selected each cycle, led to a relatively large size of these groups in the California and Los Angeles County NHANES files. For example, 1,137 and 374 of the 3,353 Mexican-Americans persons in NHANES 2007-2014 were in the California and Los Angeles County samples, respectively. Conclusion The California and Los Angeles County NHANES 1999-2006 and 2007-2014 samples are available in the National Center for Health Statistics Research Data Center.

Prevalence of chronic hepatitis B virus (HBV) infection in U.S. households: National Health and Nutrition Examination Survey (NHANES), 1988-2012.

UNLABELLED: The number of persons with chronic hepatitis B virus (HBV) infection in the United States is affected by diminishing numbers of young persons who are susceptible because of universal infant vaccination since 1991, offset by numbers of HBV-infected persons migrating to the United States from endemic countries. The prevalence of HBV infection was determined by serological testing and analysis among noninstitutionalized persons age 6 years and older for: antibody to hepatitis B core antigen (anti-HBc), indicative of previous HBV infection; hepatitis B surface antigen (HBsAg), indicative of chronic (current) infection; and antibody to hepatitis B surface antigen (anti-HBs), indicative of immunity from vaccination. These prevalence estimates were analyzed in three periods of the National Health and Nutrition Examination Survey (NHANES): 1988-1994 (21,260 persons); 1999-2008 (29,828); and 2007-2012 (22,358). In 2011-2012, for the first time, non-Hispanic Asians were oversampled in NHANES. For the most recent period (2007-2012), 3.9% had anti-HBc, indicating approximately 10.8 (95% confidence interval [CI]: 9.4-12.2) million noninstitutionalized U.S. residents having ever been infected with HBV. The overall prevalence of chronic HBV infection has remained constant since 1999: 0.3% (95% CI: 0.2-0.4), and since 1999, prevalence of chronic HBV infection among non-Hispanic blacks has been 2- to 3-fold greater than the general population. An estimated 3.1% (1.8%-5.2%) of non-Hispanic Asians were chronically infected with HBV during 2011-2012, which reflects a 10-fold greater prevalence than the general population. Adjusted prevalence of vaccine-induced immunity increased 16% since 1999, and the number of persons (mainly young) with serological evidence of vaccine protection from HBV infection rose from 57.8 (95% CI: 55.4-60.1) million to 68.5 (95% CI: 65.4-71.2) million. CONCLUSION: Despite increasing immune protection in young persons vaccinated in infancy, an analysis of chronic hepatitis B prevalence in racial and ethnic populations indicates that during 2011-2012, there were 847,000 HBV infections (which included ~400,000 non-Hispanic Asians) in the noninstitutionalized U.S. POPULATION.

Trends in Obesity Among Adults in the United States, 2005 to 2014.

IMPORTANCE: Between 1980 and 2000, the prevalence of obesity increased significantly among adult men and women in the United States; further significant increases were observed through 2003-2004 for men but not women. Subsequent comparisons of data from 2003-2004 with data through 2011-2012 showed no significant increases for men or women. OBJECTIVE: To examine obesity prevalence for 2013-2014 and trends over the decade from 2005 through 2014 adjusting for sex, age, race/Hispanic origin, smoking status, and education. DESIGN, SETTING, AND PARTICIPANTS: Analysis of data obtained from the National Health and Nutrition Examination Survey (NHANES), a cross-sectional, nationally representative health examination survey of the US civilian noninstitutionalized population that includes measured weight and height. EXPOSURES: Survey period. MAIN OUTCOMES AND MEASURES: Prevalence of obesity (body mass index ≥30) and class 3 obesity (body mass index ≥40). RESULTS: This report is based on data from 2638 adult men (mean age, 46.8 years) and 2817 women (mean age, 48.4 years) from the most recent 2 years (2013-2014) of NHANES and data from 21,013 participants in previous NHANES surveys from 2005 through 2012. For the years 2013-2014, the overall age-adjusted prevalence of obesity was 37.7% (95% CI, 35.8%-39.7%); among men, it was 35.0% (95% CI, 32.8%-37.3%); and among women, it was 40.4% (95% CI, 37.6%-43.3%). The corresponding prevalence of class 3 obesity overall was 7.7% (95% CI, 6.2%-9.3%); among men, it was 5.5% (95% CI, 4.0%-7.2%); and among women, it was 9.9% (95% CI, 7.5%-12.3%). Analyses of changes over the decade from 2005 through 2014, adjusted for age, race/Hispanic origin, smoking status, and education, showed significant increasing linear trends among women for overall obesity (P = .004) and for class 3 obesity (P = .01) but not among men (P = .30 for overall obesity; P = .14 for class 3 obesity). CONCLUSIONS AND RELEVANCE: In this nationally representative survey of adults in the United States, the age-adjusted prevalence of obesity in 2013-2014 was 35.0% among men and 40.4% among women. The corresponding values for class 3 obesity were 5.5% for men and 9.9% for women. For women, the prevalence of overall obesity and of class 3 obesity showed significant linear trends for increase between 2005 and 2014; there were no significant trends for men. Other studies are needed to determine the reasons for these trends.

Trends in Obesity Prevalence Among Children and Adolescents in the United States, 1988-1994 Through 2013-2014.

IMPORTANCE: Previous analyses of obesity trends among children and adolescents showed an increase between 1988-1994 and 1999-2000, but no change between 2003-2004 and 2011-2012, except for a significant decline among children aged 2 to 5 years. OBJECTIVES: To provide estimates of obesity and extreme obesity prevalence for children and adolescents for 2011-2014 and investigate trends by age between 1988-1994 and 2013-2014. DESIGN, SETTING, AND PARTICIPANTS: Children and adolescents aged 2 to 19 years with measured weight and height in the 1988-1994 through 2013-2014 National Health and Nutrition Examination Surveys. EXPOSURES: Survey period. MAIN OUTCOMES AND MEASURES: Obesity was defined as a body mass index (BMI) at or above the sex-specific 95th percentile on the US Centers for Disease Control and Prevention (CDC) BMI-for-age growth charts. Extreme obesity was defined as a BMI at or above 120% of the sex-specific 95th percentile on the CDC BMI-for-age growth charts. Detailed estimates are presented for 2011-2014. The analyses of linear and quadratic trends in prevalence were conducted using 9 survey periods. Trend analyses between 2005-2006 and 2013-2014 also were conducted. RESULTS: Measurements from 40,780 children and adolescents (mean age, 11.0 years; 48.8% female) between 1988-1994 and 2013-2014 were analyzed. Among children and adolescents aged 2 to 19 years, the prevalence of obesity in 2011-2014 was 17.0% (95% CI, 15.5%-18.6%) and extreme obesity was 5.8% (95% CI, 4.9%-6.8%). Among children aged 2 to 5 years, obesity increased from 7.2% (95% CI, 5.8%-8.8%) in 1988-1994 to 13.9% (95% CI, 10.7%-17.7%) (P < .001) in 2003-2004 and then decreased to 9.4% (95% CI, 6.8%-12.6%) (P = .03) in 2013-2014. Among children aged 6 to 11 years, obesity increased from 11.3% (95% CI, 9.4%-13.4%) in 1988-1994 to 19.6% (95% CI, 17.1%-22.4%) (P < .001) in 2007-2008, and then did not change (2013-2014: 17.4% [95% CI, 13.8%-21.4%]; P = .44). Obesity increased among adolescents aged 12 to 19 years between 1988-1994 (10.5% [95% CI, 8.8%-12.5%]) and 2013-2014 (20.6% [95% CI, 16.2%-25.6%]; P < .001) as did extreme obesity among children aged 6 to 11 years (3.6% [95% CI, 2.5%-5.0%] in 1988-1994 to 4.3% [95% CI, 3.0%-6.1%] in 2013-2014; P = .02) and adolescents aged 12 to 19 years (2.6% [95% CI, 1.7%-3.9%] in 1988-1994 to 9.1% [95% CI, 7.0%-11.5%] in 2013-2014; P < .001). No significant trends were observed between 2005-2006 and 2013-2014 (P value range, .09-.87). CONCLUSIONS AND RELEVANCE: In this nationally representative study of US children and adolescents aged 2 to 19 years, the prevalence of obesity in 2011-2014 was 17.0% and extreme obesity was 5.8%. Between 1988-1994 and 2013-2014, the prevalence of obesity increased until 2003-2004 and then decreased in children aged 2 to 5 years, increased until 2007-2008 and then leveled off in children aged 6 to 11 years, and increased among adolescents aged 12 to 19 years.

The association of Toxoplasma gondii infection with neurocognitive deficits in a population-based analysis.

PURPOSE: To examine the relationship between infection with Toxoplasma gondii (toxo) and cognition. METHODS: Multivariate logistic regression was used to test the association of toxo seropositivity with indices of cognitive function among over 4,200 adults in the third National Health and Nutrition Examination Survey. RESULTS: Toxo-seropositive participants were more likely than seronegative participants to score in the worst quartile of the simple reaction time test (OR 1.3, 95 % CI 1.0, 1.6), symbol-digit substitution test (SDST, OR 1.5, 95 % CI 1.2, 1.9) and the serial-digit learning test (trials to criterion) (SDLTNT, OR 1.4, 95 % CI 1.1, 1.8) in models adjusted for age, race/ethnicity, gender and foreign birth. After further adjustment for all cofactors, the association between toxo seropositivity and these outcomes was no longer significant. However, seropositivity was associated with worse scores on the SDST (OR 2.9, 95 % CI 1.8, 4.8) among those in the lowest income category and the SDLTNT (OR 1.5, 95 % CI 1.1, 2.5) among those foreign born. CONCLUSIONS: Toxo seropositivity may be associated with poor cognitive test scores in certain subgroups; however, causation cannot be established in this cross-sectional study.

National health and nutrition examination survey: analytic guidelines, 1999-2010.

Background-Analytic guide lines were first created in 1996 to assist data users in analyzing data from the Third National Health and Nutrition Examination Survey (NHANES III),conducted from 1988 to 1994 by the Centers for Disease Control and Prevention's National Center for Health Statistics. NHANES became a continuous annual survey in 1999, with data released to the public in 2-year intervals. In 2002, 2004, and 2006, guidelines were created and posted on the NHANES website to assist analysts in understanding the key issues related to analyzing data from 1999 onward. This report builds on these previous guidelines and provides the first comprehensive summary of analytic guidelines for the 1999-2010 NHANES data. Objectives-This report provides general guidelines for researchers in analyzing 1999-2010 NHANES publicly released data. Information is presented on key issues related to NHANES data, including sample design, demographic variables, and combining survey cycles. Guidance is also provided on data analysis, including the use of appropriate survey weights, calculating variance estimations, determining the reliability of estimates, age adjustment, and computing population counts.

National Health and Nutrition Examination Survey: sample design, 2007-2010.

BACKGROUND: Data collection for the National Health and Nutrition Examination Survey (NHANES) comprises three levels: a household screener, an interview, and a physical examination. The primary objective of the screener is to determine whether any household members are eligible for the interview an dexamination. Eligibility is determined by preset selection probabilities for the desired demographic subdomains. After an eligible sample person is selected, the interview collects person-level demographic, health, and nutrition information, as well as information about the household. The examination includes physical measurements, tests such as hearing and dental examinations, and the collection of blood and urine specimens for laboratory testing. OBJECTIVES: This report provides some background on the NHANES program, beginning with the first survey cycle in the 1970s and highlighting significant changes since its inception. The report then describes the broad design specifications for the 2007-2010 survey cycle, including survey objectives, domain and precision specifications, and operational requirements unique to NHANES. In addition, the report describes the details of the survey design, including the calculation of sampling rates and sample selection methods. Documentation of survey content, data collection procedures, estimation methods, and methods to assess nonsampling errors are reported elsewhere.

Association of infection with Toxoplasma gondii and Toxocara on cognitive function among US adults aged 60 and over, NHANES 2011-2014.

BACKGROUND: Toxoplasma gondii and Toxocara are common parasites that infect humans globally. Our aim was to examine the relationship between T. gondii and Toxocara infection and cognition. METHODS: Multivariate logistic regression was used to test the association of T. gondii and Toxocara seropositivity on indices of cognitive function (a word list learning trial with delayed recall from the Consortium to Establish a Registry for Alzheimer's Disease, an animal fluency test (AFT) and a digit symbol substitution test (DSST)) among 2643 adults aged 60 years and older in the 2011-2014 National Health and Nutrition Examination Survey. RESULTS: Seropositivity to T. gondii or Toxocara were both associated with lower scores in all three cognitive function measures examined in univariate analyses. Except for the DSST, these associations were not significant after adjustment for age, gender, race and Hispanic origin, poverty level, education, US birth status, depression and hypertension. On stratification to account for significant interactions, Toxocara seropositivity was associated with worse scores on the AFT among those born outside the USA, worse scores on the DSST among those aged 60-69 years, female, Hispanic and with a high school diploma or less. Lower DSST scores with Toxocara infection was greater for adults living below compared with at or above the poverty level. CONCLUSIONS: Seropositivity to these parasites, particularly to Toxocara, may be associated with diminished cognitive performance in certain subgroups of older adults.

Chlamydia trachomatis trends in the United States among persons 14 to 39 years of age, 1999-2008.

BACKGROUND: We report the first population-based assessment of national trends in chlamydia prevalence in the United States. METHODS: We investigated trends in chlamydia prevalence in representative samples of the U.S. population aged 14 to 39 years using data from five 2-year survey cycles of the National Health and Nutrition Examination Survey from 1999 to 2008. Prevalence estimates and 95% confidence intervals (CI) are reported stratified by age, gender, and race/ethnicity. Percent change in prevalence over this time period was estimated from regression models. RESULTS: In the 2007-2008 cycle, chlamydia prevalence among participants aged 14 to 39 years was 1.6% (95% CI: 1.1%-2.4%). Prevalence was higher among females (2.2%, 95% CI: 1.4%-3.4%) than males (1.1%, 95% CI: 0.7%-1.7%). Prevalence among non-Hispanic black persons was 6.7% (95% CI: 4.6%-9.9%) and was 2.5% (95% CI: 1.6%-3.8%) among adolescents aged 14 to 19 years. Over the five 2-year cycles, there was an estimated 40% reduction (95% CI: 8%-61%) in prevalence among participants aged 14 to 39 years. Decreases in prevalence were notable in men (53% reduction, 95% CI: 19%-72%), adolescents aged 14 to 19 years (48% reduction, 95% CI: 11%-70%), and adolescent non-Hispanic black persons (45%, reduction, 95% CI: 4%-70%). There was no change in prevalence among females aged 14 to 25 years, the population targeted for routine annual screening. CONCLUSIONS: On the basis of population estimates of chlamydia prevalence, the overall chlamydia burden in the United States decreased from 1999 to 2008. However, there remains a need to reduce prevalence in populations most at risk and to reduce racial disparities.

Seroprevalence of hepatitis A virus antibodies in the U.S.: results from the National Health and Nutrition Examination Survey.

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.

The prevalence of hepatitis B virus infection in the United States in the era of vaccination.

BACKGROUND: Our objective was to assess trends in the prevalence of hepatitis B virus (HBV) infection in the United States after widespread hepatitis B vaccination. METHODS: The prevalence of HBV infection and immunity was determined in a representative sample of the US population for the periods 1999-2006 and 1988-1994. National Health and Nutrition Examination Surveys participants 6 years of age were tested for antibody to hepatitis B core antigen (anti-HBc), hepatitis B surface antigen (HBsAg), and antibody to hepatitis B surface antigen (anti-HBs). Prevalence estimates were weighted and age-adjusted. RESULTS: During the period 1999-2006, age-adjusted prevalences of anti-HBc (4.7%) and HBsAg (0.27%) were not statistically different from what they were during 1988-1994 (5.4% and 0.38%, respectively). The prevalence of anti-HBc decreased among persons 6-19 years of age (from 1.9% to 0.6%; P < .01) and 20-49 years of age (from 5.9% to 4.6%; P < .01) but not among persons 50 years of age (7.2% vs 7.7%). During 1999-2006, the prevalence of anti-HBc was higher among non-Hispanic blacks (12.2%) and persons of "Other" race (13.3%) than it was among non-Hispanic whites (2.8%) or Mexican Americans (2.9%), and it was higher among foreign-born participants (12.2%) than it was among US-born participants (3.5%). Prevalence among US-born children 6-19 years of age (0.5%) did not differ by race or ethnicity. Disparities between US-born and foreign-born children were smaller during 1999-1996 (0.5% vs 2.0%) than during 1988-1994 (1.0% vs 12.8%). Among children 6-19 years of age, 56.7% had markers of vaccine-induced immunity. CONCLUSIONS: HBV prevalence decreased among US children, which reflected the impact of global and domestic vaccination, but it changed little among adults, and approximately 730,000 US residents (95% confidence interval, 550,000-940,000) are chronically infected.

Seroprevalence of antibody to mumps virus in the US population, 1999-2004.

BACKGROUND: In 2006, the largest mumps outbreak in the United States in 20 years occurred. To understand prior mumps seroprevalence and factors associated with the presence of antibody to mumps virus, data from the 1999-2004 National Health and Nutrition Examination Survey (NHANES) were analyzed. METHODS: A mumps virus-specific enzyme immunoassay was used to measure the seroprevalence of serum immunoglobulin G (IgG) antibody among NHANES participants aged 6-49 years. Participants were grouped on the basis of 10-year birth cohorts, 95% confidence intervals (CIs) were calculated using SUDAAN software, and logistic regression was used to identify independent predictors. RESULTS: The overall age-adjusted seroprevalence of IgG antibody to mumps virus during 1999-2004 was 90.0% (95% CI, 88.8%-91.1%). Seroprevalence was higher among US-born non-Hispanic blacks (96.4% [95% CI, 95.5%-97.2%]) and non-US-born Mexican Americans (93.7% [95% CI, 92.0%-95.2%]). Seroprevalence was significantly lower in the 1967-1976 birth cohort (85.7% [95% CI, 83.5%-87.8%]). The variables sex, education, and race/ethnicity/birthplace were independent predictors in at least 1 of the birth cohorts. CONCLUSIONS: The overall estimate of 90.0% is at the lower end of the estimated population immunity (90%-92%) needed to achieve herd immunity. Lower seroprevalence among groups suggest that they represent populations at an increased risk. For mumps control, high vaccine coverage and high population immunity must be achieved and maintained.

Prevalence and Trends in HIV Infection and Testing Among Adults in the United States: The National Health and Nutrition Examination Surveys, 1999-2018.

BACKGROUND: HIV antibody testing has been included in the National Health and Nutrition Examination Survey, for ages 18-49 since 1999 and for ages 18-59 years since 2009 enabling estimation of trends in HIV prevalence as part of national surveillance in the U.S. household population. Self-reported HIV testing and antiretroviral use was also included in the survey since 1999. SETTING: A continuous household-based probability sample of the U.S. population. METHODS: From 1999 to 2018, 29,020 participants age 18-49 years were tested for HIV antibody and 34,092 participants age 18-59 years were asked about self-report of any previous HIV testing. RESULTS: HIV prevalence was 0.41% among those aged 18-59 in 2009-2018 with a nonsignificant trend over time among those aged 18-49 years from 1999-2002 to 2015-2018. However, significant declines in prevalence were seen among those aged 18-39 years (0.37%-0.11%), women (0.22%-0.06%) and non-Hispanic black persons (2.14%-0.80%). Participants aged 18-39 years self-reported a decline in HIV testing, whereas those aged 40-49 and 50-59 years, non-Hispanic black persons and women reported an increase in getting a HIV test. Prevalence of infection and self-reported history of HIV testing varied by demographic and risk groups. HIV testing among HIV-positive persons was 83.9%. Antiretroviral therapy among those HIV-positive was under 50%. CONCLUSION: Although total HIV prevalence and previous self-reported HIV testing remained stable for the last 20 years, there were significant declines in age and demographic subgroups. Prevalence for both outcomes varied by demographic and risk variables.