U.S. Women with Invasive Cervical Cancer: Characteristics and Potential Barriers to Prevention.

Objectives: Although invasive cervical cancer (ICC) rates have declined since the advent of screening, the annual age-adjusted ICC rate in the United States remains 7.5 per 100,000 women. Failure of recommended screening and management often precedes ICC diagnoses. The study aimed to evaluate characteristics of women with incident ICC, including potential barriers to accessing preventive care. Materials and Methods: We abstracted medical records for patients with ICC identified during 2008-2020 in five U.S. population-based surveillance sites covering 1.5 million women. We identified evidence of adverse social and medical conditions, including uninsured/underinsured, language barrier, substance use disorder, incarceration, serious mental illness, severe obesity, or pregnancy at diagnosis. We calculated descriptive frequencies and compared potential barriers by race/ethnicity, and among women with and without symptoms at diagnosis using chi-square tests. Results: Among 1,606 women with ICC (median age: 49 years; non-White: 47.4%; stage I: 54.7%), the majority (68.8%) presented with symptoms. Forty-six percent of women had at least one identified potential barrier; 15% had multiple barriers. The most common potential barriers among all women were being underinsured/uninsured (17.3%), and language (17.1%). Presence of any potential barrier was more frequent among non-White women and women with than without symptoms (p < 0.05). Conclusions: In this population-based descriptive study of women with ICC, we identified adverse circumstances that might have prevented women from seeking screening and treatment to prevent cancer. Interventions to increase appropriate cervical cancer screening and management are critical for reducing cervical cancer rates.

Human Papillomavirus Vaccination Status and Correlates Among Mid-Adult Women: Connecticut, USA, 2016-2019.

Background: In 2019, the CDC expanded their recommendations for human papillomavirus (HPV) vaccination beyond age 26 years to include shared clinical decision-making (SCDM) among adults aged 27-45 years ("mid-adults"). The purpose of this study was to describe HPV vaccination status among mid-adult women before the implementation of SCDM for HPV vaccination. Methods: A cross-sectional survey was conducted during 2016-2019 in Connecticut, United States, and enrolled women born in 1981 or later (birth cohorts eligible for HPV vaccination). This analysis was restricted to participants aged 27 years and older at the time of the survey. Correlates of vaccination status, sources of vaccine information, and reasons for not receiving the vaccine were examined. Results: Among 298 participants, 64.4% had not received HPV vaccine. Other than age (younger age was associated with being vaccinated), no other demographic or behavioral correlates were associated with vaccination. Compared with unvaccinated women, vaccinated women were more likely to have heard about the HPV vaccine from a doctor (odds ratio [OR] = 3.45, 95% confidence interval [CI]: 2.00-5.88) and less likely to have heard about it from television (OR = 0.23, 95% CI: 0.13-0.41). The main reasons for not being vaccinated were "vaccine not offered" (48%) and "too old" (40%). Conclusions: A majority of mid-adult women in this study were not previously vaccinated against HPV, signaling the large opportunity for SCDM with this population. This may be facilitated by ensuring health care providers and mid-adult women know about the availability and potential benefits of HPV vaccination to inform decision making.

Human papillomavirus vaccine effectiveness by age at vaccination: A systematic review.

Human papillomavirus (HPV) vaccines work by preventing infections prior to natural exposure. Thus, it is likely more effective at younger ages, and it is important to understand how effectiveness might be diminished when administered at older ages. We conducted a systematic review of HPV vaccine effectiveness studies published between 2007 and 2022 that included an analysis of effectiveness against vaccine-type HPV infections, anogenital warts, cervical abnormalities and cervical cancer by age at vaccine initiation or completion. Searching multiple databases, 21 studies were included and results were summarized descriptively. Seventeen studies found the highest vaccine effectiveness in the youngest age group. Vaccine effectiveness estimates for younger adolescents ages 9-14 years ranged from approximately 74% to 93% and from 12% to 90% for adolescents ages 15-18 years. These results demonstrate that the HPV vaccine is most effective against HPV-related disease outcomes when given at younger ages, emphasizing the importance of on-time vaccination.

Failure to Complete Multidose Vaccine Series in Early Childhood.

BACKGROUND: Most early childhood immunizations require 3 to 4 doses to achieve optimal protection. Our objective was to identify factors associated with starting but not completing multidose vaccine series. METHODS: Using 2019 National Immunization Survey-Child data, US children ages 19 to 35 months were classified in 1 of 3 vaccination patterns: (1) completed the combined 7-vaccine series, (2) did not initiate ≥1 of the 7 vaccine series, or (3) initiated all series, but did not complete ≥1 multidose series. Associations between sociodemographic factors and vaccination pattern were evaluated using multivariable log-linked binomial regression. Analyses accounted for the survey's stratified design and complex weighting. RESULTS: Among 16 365 children, 72.9% completed the combined 7-vaccine series, 9.9% did not initiate ≥1 series, and 17.2% initiated, but did not complete ≥1 multidose series. Approximately 8.4% of children needed only 1 additional vaccine dose from 1 of the 5 multidose series to complete the combined 7-vaccine series. The strongest associations with starting but not completing multidose vaccine series were moving across state lines (adjusted prevalence ratio [aPR] = 1.45, 95% confidence interval [CI]: 1.18-1.79), number of children in the household (2 to 3: aPR = 1.29, 95% CI: 1.05-1.58; 4 or more: aPR = 1.68, 95% CI: 1.30-2.18), and lack of insurance coverage (aPR = 2.03, 95% CI: 1.42-2.91). CONCLUSIONS: More than 1 in 6 US children initiated but did not complete all doses in multidose vaccine series, suggesting children experienced structural barriers to vaccination. Increased focus on strategies to encourage multidose series completion is needed to optimize protection from preventable diseases and achieve vaccination coverage goals.

Clinical and Public Health Considerations for HPV Vaccination in Midadulthood: A Narrative Review.

Human papillomavirus (HPV) is an important cause of anogenital and oropharyngeal cancers, anogenital warts, and recurrent respiratory papillomatosis. Beginning in 2019, US guidelines recommended shared clinical decision-making (SCDM) for HPV vaccination among midadults (27-45 years). We conducted a narrative review of existing literature on HPV vaccination in midadults. The available evidence demonstrates that HPV vaccination in midadults is safe, efficacious, and likely to benefit both HPV-naïve midadults and those with previous infections. However, gaps in knowledge related to HPV vaccination have been identified among clinicians and midadult patients. Universal midadult HPV vaccination in the United States could avert 20 934-37 856 cancer cases over 100 years, costing $141 000-$1 471 000 per quality-adjusted life-year gained. Wide variation in these estimates reflects uncertainties in sexual behavior, HPV natural history, and naturally acquired immunity. Greater awareness among clinicians and midadult patients and broad implementation of SCDM may accelerate progress toward eliminating HPV-associated cancers and other diseases.

Understanding the Factors Influencing Health Care Provider Recommendations about Adolescent Vaccines: A Proposed Framework.

Health care provider recommendations are among the most important factors influencing parents' decisions to vaccinate their adolescents. However, delivery of high-quality health care provider recommendations for vaccination is not universal. There is wide variation in the strength, timeliness and consistency of the delivery of recommendations for all adolescent vaccines. The factors that influence health care providers' recommendations are multi-level and can be conceptualized in much the same way as vaccine acceptance among parents. Health care providers are influenced by their own attitudes and beliefs about a vaccine and also by the patient they are treating and by the community in which they practice as well as state and national level vaccine policy. We propose a multi-level framework for understanding the factors that influence health care providers' recommendations at the individual, interpersonal and community level to both develop and adapt interventions to improve providers' recommendations.

HPV type-specific trends in cervical precancers in the United States, 2008 to 2016.

Declines in cervical intraepithelial neoplasia grades 2 to 3 and adenocarcinoma in situ (CIN2+) observed among young women suggest impact from human papillomavirus (HPV) vaccination. To further evaluate vaccine impact including cross-protection and type replacement, we described high-risk (HR)-HPV type-specific cervical precancer incidence rates among women aged 20 to 39 years, 2008 to 2016. We analyzed cross-sectional population-based data on 18 344 cases of CIN2+ from a 5-site surveillance system. Diagnostic specimens were tested for individual HPV types, including 14 HR-HPV types (HPV16/18/31/33/35/39/45/51/52/56/58/59/66/68). We estimated age-specific annual HR-HPV type-specific CIN2+ incidence per 100 000 screened women for individual types, vaccine HR-HPV types (HPV16/18) and nonvaccine HR-HPV types (non-HPV16/18). We evaluated trends using average annual percent changes (AAPC) and 95% confidence intervals (CI), and estimated total declines by comparing 2015-2016 to 2008-2009 using incidence rate ratios. Among 20-24-year-olds, HPV16/18-CIN2+ declined from 2008 through 2016 (AAPC: -21.3%, 95% CI: -28.1%, -13.8%), whereas no trend was observed for non-HPV16/18-CIN2+ (AAPC: -1.8%, 95% CI: -8.1%, 4.9%). After 2010, CIN2+ among 20-24-year-olds was more often caused by nonvaccine vs vaccine HR-HPV types. No significant declining trends were observed in older age groups. In 2015-2016 compared with 2008-2009, HPV16-CIN2+ declined 78%, HPV18-CIN2+ 72% and HPV31-CIN2+ 51% among 20-24-year-olds; no increases were observed in type-specific CIN2+ incidence. Among 25-29-year-olds, HPV16-CIN2+ declined 18%; CIN2+ attributed to seven nonvaccine types increased significantly. No significant declines were observed in older groups. Significant declines in HPV16/18-CIN2+ in 20-24-year-olds and HPV16-CIN2+ in 25-29-year-olds corroborate impact of HPV vaccination. A declining trend in HPV31-CIN2+ is consistent with cross-protection from vaccination.

Messaging of Different Disease Outcomes for Human Papillomavirus Vaccination: A Systematic Review.

PURPOSE: The purpose of this systematic review was to assess how messaging for human papillomavirus (HPV) vaccination to prevent different health outcomes (sexually transmitted infection, anogenital warts ([AGW], and/or cancer) influences intentions or initiation for the vaccine series. METHODS: We searched PubMed, MEDLINE, and Embase databases for all previously published articles with an evaluation, discussion, or comparison of messages containing content about HPV infections, AGW, precancers, or cancer through June 3, 2021. Results about messages were summarized by study population and design. RESULTS: We identified 25 studies evaluating or comparing messages containing content about HPV-associated outcomes. Study designs included randomized trials (n = 12), cross-sectional surveys (n = 8), and qualitative approaches (n = 5). Few studies directly compared different messages using randomized designs or included vaccination uptake as the outcome. While many studies found support for cancer prevention messages, some studies also found equal or greater support for messages focusing on prevention of sexually transmitted infection/AGW. Variability was observed within and between studied populations (parents/adults, adolescents, young adults, healthcare providers, and adult males) and gender (male and female adolescents). DISCUSSION: A greater understanding and deeper attention to myriad health outcomes of HPV infections could increase vaccination uptake in a variety of populations for health promotion across the lifespan.

Parents' Acceptance of COVID-19 Compared to Human Papillomavirus Vaccines.

PURPOSE: The first vaccine against SARS-CoV-2 (COVID-19) for adolescents 16 years and older in the United States received Emergency Use Authorization in December 2020. Soon after its approval, parents expressed concerns about vaccine safety for adolescents. Similar concerns about vaccine safety partially explain suboptimal human papillomavirus (HPV) vaccine uptake. This qualitative study explores similarities and differences in parents' attitudes about these two vaccines. METHODS: Parents were recruited through social media and at health centers in Alabama. Semi-structured interviews with parents of adolescents aged 9-17 years were conducted before and after Alabama expanded age eligibility to those 16 and older. Topics included knowledge about HPV and COVID-19 vaccines, and parents' intentions to have children vaccinated. Interviews were analyzed using thematic analysis. RESULTS: From March 11, 2021 to April 24, 2021, 21 in-depth interviews were conducted. Parents discussed the importance of HPV and COVID-19 vaccines for protecting their children's health but differences between the two related to community protection. Parents were concerned about vaccine safety but media coverage about the COVID-19 vaccine led to more favorable attitudes about the benefits of vaccination, which was not observed for HPV vaccines. Instead for HPV vaccination, parents wanted their healthcare providers' opinions about the vaccine before making a vaccination decision. DISCUSSION: Parents had similar concerns about HPV and COVID-19 vaccines. Although provider recommendations can improve vaccine uptake, local news reports were seen to have a positive impact on COVID-19 vaccine acceptance in lieu of provider recommendation. Disseminating information online could be beneficial to promote HPV and COVID-19 vaccines.

Chlamydia Vaccination: Parent Opinions and Implications for Future Promotion Programs.

BACKGROUND: Chlamydia vaccines are currently under development and have the potential to lower the incidence of infection and disease, which are highest among adolescents and young adults. Ideally, a chlamydia vaccine would be administered to adolescents before sexual debut, a time when parents are the primary vaccine decision makers. This study explores parent opinions about an adolescent chlamydia vaccine to understand barriers and facilitators to uptake. METHODS: Semistructured interviews were conducted with parents of adolescents. Topics included conversations parents have with their children about chlamydia, opinions on chlamydia vaccine development, and vaccine characteristics, such as efficacy and cost. Interviews were analyzed using a thematic analysis approach. RESULTS: From March to April 2021, 21 interviews were completed. Few parents discuss chlamydia with their children and sex education was seen as limited. Overall, 16 parents indicated that a chlamydia vaccine is needed. However, there were mixed opinions about vaccinating their own children, related to the need to vaccinate at a young age, vaccine efficacy, and confusion about benefits of vaccination. Finally, healthcare provider recommendations were seen as important before deciding to vaccinate a child. CONCLUSIONS: Although parents think that chlamydia vaccines are needed, lack of awareness about infections and potential benefits of vaccination could serve as barriers to uptake. Healthcare provider recommendations can help to improve knowledge and vaccine uptake. However, there is a need for multilevel approaches to improve chlamydia awareness and ensure that vaccination initiation and completion rates remain high.

Perceived Need and Acceptance of a Future Chlamydia Vaccine Among Health Care Providers.

BACKGROUND: Chlamydia vaccination is a potentially important strategy to prevent infections and reduce the global burden of disease. Ideally, chlamydia immunization programs would require vaccinating adolescents before they engage in sexual activity. Communication by health care providers (HCPs) has been shown to have an impact on vaccine acceptance. Therefore, it is imperative to understand their opinions on chlamydia vaccines and factors that would promote strong vaccine recommendations to patients to promote uptake. METHODS: Semi-structured interviews with adolescent HCPs were conducted and focused on perceived need for chlamydia vaccine. Additional topics included vaccine characteristics, such as efficacy, cost, and booster vaccines, and potential vaccine recommendation strategies. RESULTS: From January to July 2021, 22 interviews were completed. Health care providers discussed how chlamydia vaccines are needed, especially in settings with high prevalence rates. Health care providers thought a chlamydia vaccine would need to be very efficacious in preventing infections and related sequalae and cost-effective. However, there were concerns about low completion rates if this vaccine required multiple doses or boosters. In addition, vaccine misinformation was prevalent among HCPs regarding potential benefits of vaccination. CONCLUSIONS: Health care providers' perceptions that an adolescent chlamydia vaccine would be beneficial offers great promise for future promotion. However, there is need for targeted education programs about chlamydia and the benefits of vaccination for HCPs. These programs will be especially important in order for HCPs to effectively communicate about the benefits of vaccination to parents and adolescents provide strong vaccine recommendations.

Assessment of Clinical Effectiveness of BNT162b2 COVID-19 Vaccine in US Adolescents.

Importance: The emergence of the B.1.617.2 (Delta) variant of SARS-CoV-2 has led to increases in both infections and hospitalizations among adolescents. Little is known about the effectiveness of the BNT162b2 vaccine in adolescents in the general population, as opposed to a clinical trial population. Objective: To estimate the effectiveness of the BNT162b2 vaccine in adolescents aged 12 to 18 years. Design, Setting, and Participants: This was a matched case-control study among adolescents (aged 12-18 years) who had results from a SARS-CoV-2 reverse transcription-polymerase chain reaction (RT-PCR) test. Immunization histories, relevant clinical data, and RT-PCR test results were obtained from the Yale New Haven Health System's medical records between June 1, 2021, and August 15, 2021, when the Delta variant caused 92% of infections in Connecticut. Case participants were defined as adolescents who had a positive test result and an associated medical encounter. Control participants were defined as those who had a negative test result and were matched to a case participant by age, county of residence, and date of testing. Exposures: Adolescents were defined as fully immunized if they had received 2 doses of vaccine at least 14 days before focal time. Main Outcomes and Measures: The primary outcome measured was SARS-CoV-2 infection confirmed by RT-PCR. The vaccine's effectiveness (VE) was estimated using matched odds ratios from conditional logistic regression models. Secondary measures included estimated VE by clinical symptoms, number of vaccine doses received, and elapsed time from immunization. Results: A total of 6901 adolescents were tested for SARS-CoV-2. The final sample comprised 186 case participants and 356 matched control participants. The median age was 14 (IQR, 13-16) years, 262 (48%) identified as female, 81 (15%) as Black, 82 (15%) as Hispanic, and 297 (55%) as White. Overall, 134 (25%) were fully immunized (case participants, 10 [5%]; control participants, 124 [35%]). The median time between immunization and the SARS-CoV-2 test was 62 days (range, 17-129 days). Within 4 months of receiving 2 doses, VE against any infection was estimated to be 91% (95% CI, 80%-96%); against asymptomatic infection, 85% (95% CI, 57%-95%). Effectiveness after a single dose was estimated to be 74% (95% CI, 18%-92%). Conclusions and Relevance: In this retrospective case-control study of US adolescents, 2 doses of BNT162b2 vaccine appeared to provide excellent protection for at least 4 months after immunization against both symptomatic and asymptomatic SARS-CoV-2 infections.

Trends in Precancerous Cervical Lesions by Area-Based Measures of Poverty, Race, and Ethnicity, Connecticut, 2008-2018.

OBJECTIVES: Trends in the incidence of precancerous cervical lesions can be monitored to evaluate the impact of human papillomavirus (HPV) vaccination. The objective of this analysis was to determine whether declines in precancerous cervical lesions varied by area-based measures of poverty, race, and ethnicity. METHODS: We analyzed 11 years of incidence data (2008-2018) from a statewide active surveillance system of precancerous cervical lesions in Connecticut. We divided area-based measures of poverty, race, and ethnicity (percentage of the population in a census tract who were living below the federal poverty level, who were Black, and who were Hispanic) at the census-tract level into 4 groups (<5.0%, 5.0%-9.9%, 10.0%-19.9%, ≥20.0%) using recommended cut points from the Public Health Disparities Geocoding Project. We estimated incidence rates and average annual percentage changes (AAPCs) stratified by age and each area-based measure using Joinpoint regression software. We used total population and estimated screened population as denominators for each age group to calculate rates and AAPCs. RESULTS: During 2008-2018 in Connecticut, 18 878 women aged 21-39 were diagnosed with precancerous cervical lesions. After adjusting for screening, the largest declines occurred among women aged 21-24 (AAPC = -11.5%; 95% CI, -13.6% to -9.4%). We found significant and similar annual declines (~10%-12%) in this age group across all 4 levels of poverty, race, and ethnicity. CONCLUSIONS: This analysis adds to the growing body of evidence demonstrating the positive impact of population-level HPV vaccination among young women that appears similar across area-based measures of sociodemographic characteristics. Monitoring is necessary to ensure the continuation of this progress in all communities.

Patterns of recommended vaccine receipt among women ages 24-45 years: a cross-sectional analysis.

BACKGROUND: Vaccine receipt among mid-adults remains low, with only one quarter of adults being up to date for all recommended vaccines. It is important to understand the myriad factors that influence vaccine receipt among mid-adult women to address these low rates. METHODS: We conducted a cross-sectional analysis of data from women ages 24-45 years collected as part of an ongoing case-control study of the effectiveness of HPV vaccine. We examined associations between demographic characteristics and healthcare utilization and receipt of individual vaccines and combinations of multiple vaccines using logistic regression analyses for three routinely recommended vaccines: tetanus, influenza and HPV. RESULTS: Among the 309 women enrolled in the study, only 19 (6.2%) were up to date for all three recommended vaccines and 41 (13.3%) had not received any of the recommended vaccines. A greater number of health care visits in the past year was associated with receipt of influenza (aOR = 6.37, 95% CI = 2.53, 16.1) and tetanus (aOR = 2.17, 95% CI = 1.14, 4.12) vaccines. White women were more likely to have received HPV vaccine (aOR = 2.39, 95% CI = 1.07, 5.36). CONCLUSIONS: Uptake of recommended vaccines is low among young and mid-adult women. There is a need for greater understanding of the underlying factors influencing vaccine receipt in this population.

Factors Associated With Receipt of Meningococcal B Vaccine Among United States Adolescents, National Immunization Survey-Teen, 2017-2018.

PURPOSE: In this study, we evaluated factors associated with receipt of meningococcal serogroup B (MenB) vaccine among adolescents in the United States. METHODS: We used public use data files from the National Immunization Survey-Teen from 2017 to 2018. Logistic regression was used to model associations among sociodemographic, healthcare, and vaccination variables of interest and MenB vaccine receipt (≥1 vs. 0 dose). To explore associations between state-level meningococcal vaccination requirements and MenB vaccine uptake, we performed a secondary analysis stratified by presence of a quadrivalent meningococcal (MenACWY) vaccination requirement for secondary school attendance in the adolescent's state of residence (no requirement vs. a one- or two-dose requirement). RESULTS: Among 7,288 adolescents, MenB vaccine receipt was significantly associated with up-to-date human papillomavirus (adjusted odds ratio [aOR] 1.74, 95% confidence interval [CI] 1.29-2.35) and MenACWY (aOR 5.81, 95% CI 4.14-8.13) vaccination status in multivariable analysis. Adolescents with private insurance were less likely to be vaccinated (aOR .61, 95% CI .46-.79) compared to adolescents with other health insurance types. In secondary analyses, health insurance was no longer significantly associated with MenB vaccine uptake among adolescents in states with a MenACWY requirement. CONCLUSIONS: We found that MenB vaccination is associated with receipt of other vaccines recommended for use in adolescents. Adolescents with private health insurance were less likely to be vaccinated against MenB, although state MenACWY requirements appeared to modify the effect of insurance on MenB vaccine receipt. Further work to understand how these factors may influence delivery and acceptance of MenB vaccine can inform interventions and strategies to improve uptake.

Increases in Human Papillomavirus Testing Preceding Diagnosis of Cervical Precancer in 5 US States, 2008-2016.

OBJECTIVE: The aim of the study was to describe trends in human papillomavirus (HPV) testing preceding diagnosis of cervical precancer during a time of changing screening recommendations. MATERIALS AND METHODS: We conducted a cross-sectional analysis of data from active, population-based, laboratory surveillance among 1.5 million residents of 5 areas in the United States. We included women aged 21-39 years diagnosed with cervical intraepithelial neoplasia grades 2, 2/3, or 3 or adenocarcinoma in situ (collectively, CIN2+) during 2008-2016, who had a cytology and/or HPV test before diagnosis (n = 16,359). RESULTS: The proportion of women with an HPV test preceding CIN2+ increased from 42.9% in 2008 to 73.3% in 2016 (p < .01); testing increased in all age groups (21-24 y: 35.3% to 47.6%, 25-29 y: 40.9% to 64.1%, 30-39 y: 51.7% to 85.9%, all p < .01). The HPV testing varied by cytology result and was highest among women with atypical squamous cells of unknown significance (n = 4,310/4,629, 93.1%), negative for intraepithelial lesion or malignancy (n = 446/517, 86.3%), and atypical glandular cells (n = 145/257, 56.4%). By 2016, at least half of all cases in every surveillance area had an HPV test before diagnosis. CONCLUSIONS: During 2008-2016, the proportion of women with an HPV test preceding CIN2+ increased significantly for all age groups, cytology results, and surveillance areas. By 2016, most (85.9%) women aged 30-39 years had an HPV test, consistent with recommendations. Increasing utilization of HPV tests, which have demonstrated improved sensitivity for detecting cervical disease, may in part explain increasing rates of cervical precancer among women 30 years and older.

SARS-CoV-2 in Nursing Homes after 3 Months of Serial, Facilitywide Point Prevalence Testing, Connecticut, USA.

Nursing homes house populations that are highly vulnerable to coronavirus disease. Point prevalence surveys (PPSs) provide information on the severe acute respiratory syndrome coronavirus 2 infection status of staff and residents in nursing homes and enable isolation of infectious persons to halt disease spread. We collected 16 weeks of public health surveillance data on a subset of nursing homes (34/212) in Connecticut, USA. We fit a Poisson regression model to evaluate the association between incidence and time since serial PPS onset, adjusting for decreasing community incidence and other factors. Nursing homes conducted a combined total of 205 PPSs in staff and 232 PPSs in residents. PPS was associated with 41%-80% reduction in incidence rate in nursing homes. Our findings provide support for the use of repeated PPSs in nursing home staff and residents, combined with strong infection prevention measures such as cohorting, in contributing to outbreak control.

Effectiveness of HPV vaccine by age at vaccination and number of doses: protocol for a population-based matched case-control study.

INTRODUCTION: In 2006, the first human papillomavirus (HPV) vaccine was approved by the Food and Drug Administration in the USA based on pre-licensure clinical trials that found it to be highly efficacious at preventing persistent infection and precancerous, high-grade cervical lesions (HGCLs) caused by viral types the vaccine protects against. However, the real-world effectiveness of HPV vaccines as used in clinical practice may be quite different from the efficacy found in pre-licensure clinical trials. More than 10 years have passed since the introduction of the vaccine programme. It is critical to determine if the full benefits of HPV are being realised in real-world settings. METHODS AND ANALYSIS: The objectives of this study were to estimate the effectiveness of HPV vaccines as used in real-world clinical settings and to determine the degree to which the vaccine's effectiveness varies based on age at the time of immunisation and the number of doses received. The study will be a population-based, matched case-control study. Cases will be women with newly diagnosed HGCL associated with HPV types 16 and 18. Matched controls will be women with a normal Pap test result, matched individually to cases in a 2:1 ratio by age, a practice and date of testing. Medical records will be reviewed to determine dates of receipt of the HPV vaccine for all participants. We will use multivariate conditional logistic regression to control for potential confounders. ETHICS AND DISSEMINATION: This protocol presents minimal risk to the subjects. This protocol has received approval from the Institutional Review Board of Yale University (HIC: 1502015308), and a Health Insurance Portability and Accountability Act (HIPAA) Waiver of Authorisation has been granted to allow investigators to recruit subjects for the study. Findings will be disseminated through peer-reviewed, open-access scientific journals and conference presentations.