Susan Hariri

Reduction in Human Papillomavirus (HPV) Prevalence Among Young Women Following HPV Vaccine Introduction in the United States, National Health and Nutrition Examination Surveys, 2003–2010

BACKGROUND Human papillomavirus (HPV) vaccination was introduced into the routine immunization schedule in the United States in late 2006 for females aged 11 or 12 years, with catch-up vaccination recommended for those aged 13-26 years. In 2010, 3-dose vaccine coverage was only 32% among 13-17 year-olds. Reduction in the prevalence of HPV types targeted by the quadrivalent vaccine (HPV-6, -11, -16, and -18) will be one of the first measures of vaccine impact. METHODS We analyzed HPV prevalence data from the vaccine era (2007-2010) and the prevaccine era (2003-2006) that were collected during National Health and Nutrition Examination Surveys. HPV prevalence was determined by the Linear Array HPV Assay in cervicovaginal swab samples from females aged 14-59 years; 4150 provided samples in 2003-2006, and 4253 provided samples in 2007-2010. RESULTS Among females aged 14-19 years, the vaccine-type HPV prevalence (HPV-6, -11, -16, or -18) decreased from 11.5% (95% confidence interval [CI], 9.2-14.4) in 2003-2006 to 5.1% (95% CI, 3.8-6.6) in 2007-2010, a decline of 56% (95% CI, 38-69). Among other age groups, the prevalence did not differ significantly between the 2 time periods (P > .05). The vaccine effectiveness of at least 1 dose was 82% (95% CI, 53-93). CONCLUSIONS Within 4 years of vaccine introduction, the vaccine-type HPV prevalence decreased among females aged 14-19 years despite low vaccine uptake. The estimated vaccine effectiveness was high.

Prevalence of Genital Human Papillomavirus Among Females in the United States, the National Health and Nutrition Examination Survey, 2003–2006

BACKGROUND Genital human papillomaviruses (HPV) include >40 sexually transmitted viruses. Most HPV infections do not progress to disease, but infection with certain types of HPV can cause cervical and other anogenital and oropharyngeal cancer, and other types of HPV are associated with anogenital warts. HPV vaccines prevent infection with HPV 16 and 18, which account for 70% of cases of cervical cancer, and HPV 6 and 11, which cause 90% of the cases of anogenital warts. METHODS Using data and self-collected cervicovaginal specimens from 4150 females, 14-59 years of age, from consecutive National Health and Nutrition Examination Surveys (2003-2006), we estimated the prevalence of type-specific HPV DNA and examined sociodemographic and sexual determinants. RESULTS The overall prevalence of HPV was 42.5% in females 14-59 years of age and varied significantly by age, race or ethnicity, and number of sex partners. Individual type prevalence was less than 7%, ranging from <0.5% through 6.5%. The most common type was nononcogenic HPV 62 (found in 6.5% of subjects), followed by HPV 53 and HPV 16 (4.7%), both of which are oncogenic types. The most prevalent species was nononcogenic α3. CONCLUSIONS HPV infection is common among US females, with the highest burden of infection found in young females 20-24 years of age. Monitoring trends in HPV type distribution will contribute to our understanding of the early impact of HPV vaccines.

Prevalence of HPV After Introduction of the Vaccination Program in the United States

BACKGROUND: Since mid-2006, human papillomavirus (HPV) vaccination has been recommended for females aged 11 to 12 years and through 26 years if not previously vaccinated. METHODS: HPV DNA prevalence was analyzed in cervicovaginal specimens from females aged 14 to 34 years in NHANES in the prevaccine era (2003–2006) and 4 years of the vaccine era (2009–2012) according to age group. Prevalence of quadrivalent HPV vaccine (4vHPV) types (HPV-6, -11, -16, and -18) and other HPV type categories were compared between eras. Prevalence among sexually active females aged 14 to 24 years was also analyzed according to vaccination history. RESULTS: Between the prevacccine and vaccine eras, 4vHPV type prevalence declined from 11.5% to 4.3% (adjusted prevalence ratio [aPR]: 0.36 [95% confidence interval (CI): 0.21–0.61]) among females aged 14 to 19 years and from 18.5% to 12.1% (aPR: 0.66 [95% CI: 0.47–0.93]) among females aged 20 to 24 years. There was no decrease in 4vHPV type prevalence in older age groups. Within the vaccine era, among sexually active females aged 14 to 24 years, 4vHPV type prevalence was lower in vaccinated (≥1 dose) compared with unvaccinated females: 2.1% vs 16.9% (aPR: 0.11 [95% CI: 0.05–0.24]). There were no statistically significant changes in other HPV type categories that indicate cross-protection. CONCLUSIONS: Within 6 years of vaccine introduction, there was a 64% decrease in 4vHPV type prevalence among females aged 14 to 19 years and a 34% decrease among those aged 20 to 24 years. This finding extends previous observations of population impact in the United States and demonstrates the first national evidence of impact among females in their 20s.

Post-licensure monitoring of HPV vaccine in the United States ☆

Post-licensure evaluation of vaccines plays an important role in monitoring the progress of immunization programs, demonstrating population impact of vaccines, and providing data for ongoing policy decisions. Two human papillomovirus (HPV) vaccines are licensed and recommended for use in females in the United States, a quadrivalent human HPV vaccine, licensed in 2006 and a bivalent vaccine HPV vaccine licensed in 2009. HPV vaccination is recommended for females 11 or 12 years of age with catch-up vaccination through age 26 years. Post-licensure monitoring of the HPV vaccine program has included some of the same systems established for other vaccines, such as those for vaccine safety and coverage monitoring. However, monitoring HPV vaccine impact on infection and disease outcomes has required new efforts. While there are well established cancer registries in the United States, it will take decades before the impact of vaccine on cervical cancer is observed. More proximal measures of vaccine impact include outcomes such as prevalence of HPV vaccine types, incidence of cervical precancers and genital warts. We review systems in place or being established for post-licensure monitoring of HPV vaccine in the United States.

The estimated lifetime probability of acquiring human papillomavirus in the United States.

Background Estimates of the lifetime probability of acquiring human papillomavirus (HPV) can help to quantify HPV incidence, illustrate how common HPV infection is, and highlight the importance of HPV vaccination. Methods We developed a simple model, based primarily on the distribution of lifetime numbers of sex partners across the population and the per-partnership probability of acquiring HPV, to estimate the lifetime probability of acquiring HPV in the United States in the time frame before HPV vaccine availability. Results We estimated the average lifetime probability of acquiring HPV among those with at least 1 opposite sex partner to be 84.6% (range, 53.6%–95.0%) for women and 91.3% (range, 69.5%–97.7%) for men. Under base case assumptions, more than 80% of women and men acquire HPV by age 45 years. Conclusions Our results are consistent with estimates in the existing literature suggesting a high lifetime probability of HPV acquisition and are supported by cohort studies showing high cumulative HPV incidence over a relatively short period, such as 3 to 5 years.

Human papillomavirus vaccine coverage in the United States, National Health and Nutrition Examination Survey, 2007-2008.

OBJECTIVES This study aims to estimate human papillomavirus (HPV) vaccine coverage by demographic and sexual behavior characteristics 1-2 years after vaccine licensure in a nationally representative sample of females aged 9-59 years in the United States. METHODS In 2007-2008, a total of 2775 females aged 9-59 years responded to questions on HPV vaccine receipt in the National Health and Nutrition Examination Survey (NHANES). Demographic and sexual characteristics were evaluated for select age categories in bivariate analyses after adjusting for survey design. RESULTS Overall, 15.2% of females aged 11-26 years reported HPV vaccine initiation; vaccine initiation varied significantly by age. We found no significant difference in vaccine initiation by race or poverty level in either 11-18 or 19-26-year olds. Significantly more 19-26-year olds with private insurance initiated vaccine (16.3%) than those with public insurance (4.0%) (p = 0.04). Among females aged 14-18 years, vaccine initiation was higher in those who ever had sex (28.6%) compared to those who had never had sex (17.8%) (p = 0.05). CONCLUSIONS These results describe HPV vaccine initiation shortly after vaccine licensure. Vaccine initiation was highest in females aged 14-18 years. Efforts should be made to increase HPV vaccine coverage for the recommended age groups.

Reduction in HPV 16/18-associated high grade cervical lesions following HPV vaccine introduction in the United States – 2008–2012☆

BACKGROUND Prevention of pre-invasive cervical lesions is an important benefit of HPV vaccines, but demonstrating impact on these lesions is impeded by changes in cervical cancer screening. Monitoring vaccine-types associated with lesions can help distinguish vaccine impact from screening effects. We examined trends in prevalence of HPV 16/18 types detected in cervical intraepithelial neoplasia 2, 3, and adenocarcinoma in situ (CIN2+) among women diagnosed with CIN2+ from 2008 to 2012 by vaccination status. We estimated vaccine effectiveness against HPV 16/18-attributable CIN2+ among women who received ≥1 dose by increasing time intervals between date of first vaccination and the screening test that led to detection of CIN2+ lesion. METHODS Data are from a population-based sentinel surveillance system to monitor HPV vaccine impact on type-specific CIN2+ among adult female residents of five catchment areas in California, Connecticut, New York, Oregon, and Tennessee. Vaccination and cervical cancer screening information was retrieved. Archived diagnostic specimens were obtained from reporting laboratories for HPV DNA typing. RESULTS From 2008 to 2012, prevalence of HPV 16/18 in CIN2+ lesions statistically significantly decreased from 53.6% to 28.4% among women who received at least one dose (Ptrend<.001) but not among unvaccinated women (57.1% vs 52.5%; Ptrend=.08) or women with unknown vaccination status (55.0% vs 50.5%; Ptrend=.71). Estimated vaccine effectiveness for prevention of HPV 16/18-attributable CIN2+ was 21% (95% CI: 1-37), 49% (95% CI: 28-64), and 72% (95% CI: 45-86) in women who initiated vaccination 25-36 months, 37-48 months, and >48 months prior to the screening test that led to CIN2+ diagnosis. CONCLUSIONS Population-based data from the United States indicate significant reductions in CIN2+ lesions attributable to types targeted by the vaccines and increasing HPV vaccine effectiveness with increasing interval between first vaccination and earliest detection of cervical disease.

Adolescent Vaccination-Coverage Levels in the United States: 2006–2009

BACKGROUND: From 2005 through 2007, 3 vaccines were added to the adolescent vaccination schedule: tetanus-diphtheria-acellular pertussis (TdaP); meningococcal conjugate (MenACWY); and human papillomavirus (HPV) for girls. OBJECTIVE: To assess implementation of new adolescent vaccination recommendations. METHODS: Data from the 2006–2009 National Immunization Survey–Teen, an annual provider-verified random-digit-dial survey of vaccination coverage in US adolescents aged 13 to 17 years, were analyzed. Main outcome measures included percentage of adolescents who received each vaccine according to survey year; potential coverage if all vaccines were administered during the same vaccination visit; and, among unvaccinated adolescents, the reasons for not receiving vaccine. RESULTS: Between 2006 and 2009, ≥1 TdaP and ≥1 MenACWY coverage increased from 11% to 56% and 12% to 54%, respectively. Between 2007 and 2009, ≥1 HPV coverage among girls increased from 25% to 44%; between 2008 and 2009, ≥3 HPV coverage increased from 18% to 27%. In 2009, vaccination coverage could have been >80% for Td/TdaP and MenACWY and as high as 74% for the first HPV dose if providers had administered all recommended vaccines during the same vaccination visit. For all years, the top reported reasons for not vaccinating were no knowledge about the vaccine, provider did not recommend, and vaccine is not needed/necessary (for TdaP and MenACWY) and adolescent is not sexually active, no knowledge about the vaccine, and vaccine is not needed/necessary (for HPV). CONCLUSIONS: Adolescent vaccination coverage is increasing but could be improved. Strategies are needed to increase parental knowledge about adolescent vaccines and improve provider recommendation and administration of all vaccines during the same visit.

Population impact of HPV vaccines: summary of early evidence.

Human papillomavirus (HPV) vaccines are available in the United States and around the world to prevent HPV-associated diseases including cervical cancer and genital warts. HPV vaccination is currently recommended for adolescents: target ages for routine and catch-up vaccinations vary by country. Because the time from vaccination to cancer development can be several decades, many studies are evaluating more immediate outcomes. In the 4 years since the vaccine was introduced, reductions in HPV vaccine type prevalence and genital warts have been reported in young females in the United States and other countries. Many questions remain about the long-term impact, but the initial studies show promising results for the relatively new HPV vaccine.

Epidemiology of Human Immunodeficiency Virus in the United States

SUMMARY The human immunodeficiency virus (HIV) epidemic emerged in the early 1980s with HIV infection as a highly lethal disease among men who have sex with men and among frequent recipients of blood product transfusions. Advances in the treatment of HIV infection have resulted in a fundamental shift in its epidemiology, to a potentially chronic and manageable condition. However, challenges in the prevention of this infection remain. In particular, increasing evidence suggests that transmission of drug-resistant virus is becoming more common and that the epidemic is having a profound impact on morbidity and mortality in ethnic and racial minority subgroups in the United States. New population-based data collection systems designed to describe trends in behaviors associated with HIV transmission and better methods for measuring the true incidence of transmission will better elucidate the characteristics of HIV infection in the United States and inform future public health policies.