Vaccine Series Completion Research Articles

P-2074. Evaluation of Adherence and Access to Booster COVID-19 Vaccination in Persons with HIV

Abstract Background COVID-19 disproportionately effects minority communities. Completion of the primary COVID-19 vaccination series (≥ 2 doses) is recommended for all American adults by the Centers for Disease Control and Prevention. A population with high mortality and morbidity related to COVID-19 is persons with HIV (PWH). The Infectious Diseases Practice (IDP) at University Hospital (UH) has been providing care to PWH for over 30 years, and it was one of the designated COVID-19 vaccination centers early in the pandemic. We compared rates of PWH who receive COVID-19 vaccine (incomplete: < 2, complete: ≥ 2) amongst different demographic factors to better understand subgroups that can benefit from additional messaging to promote vaccine uptake. Methods A retrospective chart review study was conducted at the IDP at UH, Newark. Adult PWH (18-88 years old) who had an office visit to the clinic between January 2021-December 2022 were included. Demographic variables and COVID vaccine count were collected. Results The IDP identified PWH (mean age 52, 75.4% Black, 20.4% Hispanic, 39.5% women) who had either complete (n=1085) or incomplete (n=815) primary vaccine schedules for COVID-19. The most common HIV risk factors were heterosexual contact (52.8%), homosexual contact (28.16%), and injection drug use (8.58%). 54% of patients had a CD4+ count > 499, 87.08% of patients had an HbA1c < 6.4, and 72.68% of patients had an HIV viral load that was undetectable. Notably, PWH who completed the primary vaccination series were more likely to be undetectable (80.6%) years compared to PWH who did not complete their vaccination series (62.1%). Furthermore, PWH who completed the primary vaccination series were more likely to have an HbA1c< 6.4 (83.1%) compared to PWH who did not complete their vaccination series (77.9%). PWH who completed the primary vaccination series were more likely to have a CD4 count > 499 (54.4%) compared to PWH who did not complete their vaccination series (44.4%). Conclusion Patients most at risk of not completing the primary COVID-19 vaccine schedule include PWH who are virally uncontrolled, persons with diabetes, or have a low CD4+ count. This indicates medical adherence should be targeted in such populations to improve their healthcare outcomes. Disclosures Shobha Swaminathan, MD, Viiv Healthcare: Advisor/Consultant

P-599. 6-Valent, OspA-Based VLA15 Lyme Disease Vaccine Candidate Against Lyme Borreliosis in a Healthy Pediatric and Adult Study Population: A Phase 2 Study Update

Abstract Background Lyme borreliosis (LB) is the most common tick-borne disease in the US, with approximately 476,000 cases diagnosed and treated annually and nearly 90 million individuals living in high incidence jurisdictions. Vector-focused prevention measures have varying levels of effectiveness due to low utilization, poor adherence, or high cost. A safe and efficacious vaccine to prevent LB is warranted. We provide an update on the Pfizer-Valneva VLA15 vaccine clinical development program, specifically the safety and immunogenicity booster data of the phase 2 trial (NCT04801420). Methods A randomized, observer-blinded, multi-centre Phase 2 study investigated the safety and immunogenicity of VLA15 in adult and pediatric study populations. A total of 625 participants aged 5-65 years were enrolled in three age groups (5-11 years, 12-17 years, and 18-65 years) and randomized 1:1:1 to receive VLA15 180 mcg with alum in a three-dose (Month 0-2-6) or a two-dose schedule (Month 0-6), or three injections of placebo (Month 0-2-6) followed by booster doses at Month 18 and Month 30. Safety and immunogenicity data up to one month after completion of the primary vaccination series and yearly booster doses are presented. Results Up to Month 19, VLA15 was safe and well tolerated in all age groups after all doses. Most adverse reactions were mild or moderate in severity. No related SAEs or other safety concerns were reported. The VLA15 booster dose induced a robust, anamnestic immune response against all six OspA vaccine serotypes in all age groups. Immune responses in children were higher than in adults across both schedules. Conclusion The Month 18 VLA15-221 booster dose was safe and immunogenic in both adults and children. The Month 30 booster data is under analysis. The ongoing blinded Phase 3 trials in Europe and North America will provide additional data which may support use of this vaccine as the primary preventative measure to protect against LB. Disclosures Marc D. Messier, PhD, SOBI: Advisor/Consultant|Valneva: employee|Valneva: Ownership Interest Laura Wagner, M.Sc., Valneva: employee Romana Hochreiter, PhD, Valneva Austria GmbH: WO2021/207615 A1|Valneva Austria GmbH: Employee, owner of stock options Erik Lamberth, MD, Pfizer: Employee|Pfizer: Stocks/Bonds (Public Company) Julian Larcher-Senn, PhD, Valneva: Advisor/Consultant Raphael Simon, PhD, Pfizer: Stocks/Bonds (Private Company) James groark, MD, Pfizer: Stocks/Bonds (Public Company) James H. Stark, PhD, Pfizer: Employee|Pfizer: Stocks/Bonds (Public Company)

The Effects of Motivational Interviewing on Promoting Human Papillomavirus Vaccination Initiation and Completion Among South Asian Mother/Daughter Dyads: A Pilot Randomised Controlled Trial.

Vaccination against HPV is an effective strategy for the prevention of HPV infection and cervical cancer. Nevertheless, the HPV vaccine uptake rate is low among ethnic minorities in Hong Kong. This study sought to assess the feasibility and acceptability of motivational interviewing among South Asian mother-daughter dyads and to preliminarily examine its effects on knowledge of HPV infection and vaccination, health beliefs, intention to have the daughters vaccinated, and initiation and completion of HPV vaccine series. This was a pilot randomised controlled trial. Forty South Asian mothers with at least one daughter aged 9 to 17years were recruited. The intervention group received a motivational interviewing intervention whereas the control group received usual care. Structured questionnaires were used to collect data on the participants' characteristics and selected outcome variables. Bias-corrected Hedges' g and rate difference together with their 95% confidence intervals were calculated to estimate the effect sizes of the intervention on the outcomes The acceptability was assessed via semi-structured interviews. A larger proportion of the daughters of the intervention group participants had received the first dose of HPV vaccine (95% [19 out of 20]) vs 0% [0 out of 20]). The intervention group showed greater improvement in knowledge at 3months after the intervention (Hedges' g = 0.77 (95%CI:0.13-1.41)). Most interviewees were satisfied with the intervention. The intervention was feasible and acceptable. The intervention can help to increase South Asian mothers' knowledge and to increase the initiation of HPV vaccine series by their daughters. This study was registered at the Chinese Clinical Trial Registry (ChiCTR2100052751) on 5 November 2021.

Human papillomavirus vaccination coverage among adolescent boys and girls in the United States: A birth year cohort analysis of the National Immunization Survey-Teen, 2016–2022.

ObjectiveTo evaluate human papillomavirus (HPV) vaccination coverage among adolescents in the U.S. using birth cohort analysis. MethodsWe conducted a birth cohort analysis among adolescents born during 1999–2009 using National Immunization Survey-Teen (NIS-Teen), a random-digit dialed household telephone survey that also includes vaccination data from providers. We analyzed 131,553 records from 2016 to 2022 NIS-Teen data to determine: trends in coverage with ≥1 HPV vaccine dose before age 13 years and cumulative coverage from age 13–17 years; sociodemographic factors associated with HPV vaccination before age 13 years; missed HPV vaccination opportunities and the potential achievable coverage if opportunities were not missed; and trends in completion of HPV vaccination series. Regression analysis and Kaplan-Meier method provided the average percentage increase in coverage, and cumulative coverage from age 13–17 years stratified by birth cohorts, respectively. ResultsHPV vaccination initiation before age 13 years increased from 27.0 % among adolescents born in 1999 to 69.8 % among those born in 2009. Overall, cumulative percent with ≥1 HPV vaccine dose increased from 51.3 % before age 13 years to 74.9 % through age 17 years. Having a preventive visit at ages 11–12 years and being insured were associated with higher ≥1 HPV vaccine dose coverage. Among the 38,568 (29.3 %) adolescents unvaccinated for HPV, 31,513 (82.5 %) missed ≥1 HPV vaccination opportunity. The potential achievable coverage if opportunities were not missed was 94.8 %. Completion of HPV vaccination series before age 13 years increased from 10.3 % among adolescents born in 1999 to 42.2 % among those born in 2009. ConclusionsCoverage with ≥1 HPV vaccine dose increased by birth cohort among adolescents born 1999–2009 but remained suboptimal, especially among uninsured adolescents. Missed opportunities may be reduced by effective HPV vaccination implementation and uptake strategies and by administering all recommended vaccines during the same visit.

Socioeconomic/health-related factors associated with HPV vaccination initiation/completion among females of paediatric age: A systematic review with meta-analysis.

To systematically identify, appraise, and summarise published evidence on individual socioeconomic and health-related factors associated with human papillomavirus (HPV) vaccination initiation and completion among females of paediatric age. A global systematic review with meta-analysis (PROSPERO: CRD42023445721). We performed a literature search in December 2022 and supplemented the search on August 1, 2023. Appropriate data were pooled using an inverse variance, random-effects model and the results were expressed as odds ratios, with 95% confidence intervals. A statistically significant point pooled increased/decreased odds of 30-69% was regarded to be strongly associated, and ≥70% was very strongly associated. We included 83 cross-sectional studies. Among several significantly associated factors, being an older girl: 1.67 (1.44-1.93), having health insurance: 1.41 (1.16-1.72), and being in a public school: 1.54 (1.05-2.26) strongly increased the odds of vaccination initiation, and nativity in the country of study: 1.82 (1.33-2.50), use of contraception: 2.00 (1.16-3.46), receipt of influenza vaccination: 1.75 (1.54-2.00) and having visited a healthcare provider: 1.85 (1.51-2.28) in the preceding year very strongly increased the odds of vaccination initiation. Likewise, being an older girl: 1.36 (1.23-1.49) and having visited a healthcare provider in the preceding year: 1.46 (1.05-2.04) strongly increased the odds of vaccination series completion, and school-based vaccination: 3.08 (1.05-9.07), having health insurance: 1.72 (1.27-2.33), and receipt of influenza vaccination in the preceding year: 1.72 (1.62-1.83) very strongly increased the odds of vaccination series completion. We made similar observations when the studies were limited to the United States. Several individual socioeconomic/health-related factors may determine initiating and completing the HPV vaccination series among paediatric females. These factors provide insights that may be key to identifying girls at increased risk of not being vaccinated and may aid targeted public health messaging.

COVID-19 Testing Behavior as a Predictor of COVID-19 Vaccination in Southeastern Louisiana: A Longitudinal Cohort Study.

Background: Global COVID-19 vaccination effort faces the challenges of vaccine hesitancy and resistance, rooted in misinformation and institutional distrust. Addressing these barriers with customized messaging is essential, yet the relationship between vaccine hesitancy and other health-seeking behaviors, like COVID-19 testing, has been underexplored. Method: This study assessed COVID-19 vaccine uptake in Southeastern Louisiana across 10 pharmacies and clinics in areas with historically high rates of COVID-19 infection. Using a longitudinal cohort design from Fall 2022 through Fall 2023, a total of 377 participants from diverse backgrounds were surveyed while seeking routine care at partner organizations. Baseline data was collected on demographics, vaccine knowledge, attitudes, and test-seeking behaviors. Information on COVID-19 testing and vaccination were self-reported and verified, as applicable, in the patient's medical records. All data was analyzed using descriptive statistics, log-binomial to yield risk ratios, and an ordinal logistic regression for vaccine series completion. Results: Among the 377 participants, 207 were unvaccinated while 170 received the vaccine. Among the unvaccinated individuals, 53 received a half-dose, 97 a full dose, and 14 a booster. Notably, 75% of unvaccinated and 89% of vaccinated participants underwent COVID-19 testing. Individuals who were tested were 1.71 times more likely to be vaccinated (95% CI 1.03, 2.84), while previous vaccine refusal was associated with lower vaccine acceptance (0.77; 95% CI 0.54, 1.09). In the bivariate and multivariate analysis, COVID-19 testing behavior was positively associated with COVID-19 vaccine uptake. Conclusions: Exploring the connection between COVID-19 testing and vaccination provides valuable insights for future public health messaging to mitigate vaccine hesitancy.

Disparities in COVID-19 vaccine uptake among pregnant people in a diverse urban population with high vaccine acceptance

IntroductionThis study's objective was to compare coronavirus disease 2019 (COVID-19) vaccination rates between pregnant individuals in San Francisco and the city's similar-aged population, and to identify factors associated with vaccine uptake in the pregnant population. MethodsThis was a retrospective cohort study of all patients delivering at two hospitals in San Francisco from 3/15/2021-10/15/2021. Reference COVID-19 vaccination rates for San Francisco were obtained from the California Immunization Registry. The primary outcome was completion of a COVID-19 vaccine series among pregnant individuals compared with the San Francisco general population aged 18-45 years. Secondary outcomes included factors associated with COVID-19 vaccination among pregnant people. ResultsOf 2294 pregnant individuals, 1181 (51.5%) completed a COVID-19 vaccine series by delivery. Pregnant individuals were less likely to be vaccinated than the San Francisco population throughout the study period. Factors associated with lower vaccination rates in pregnant individuals included public insurance (adjusted OR [aOR], 0.21; 95% CI, 0.16-0.27), younger age (aOR 0.74; 95% CI 0.64-0.86), English language preference (aOR 0.58, 95% CI 0.42-0.80), and self-identified Black (aOR 0.26, 95% CI 0.17-0.40; Reference: White), Hispanic (aOR 0.61, 95% CI 0.46-0.81), or Other (aOR 0.50, 95% CI 0.36-0.68) race or ethnicity. ConclusionsCOVID-19 vaccination coverage among pregnant people in San Francisco lagged behind the city's similar-aged population, particularly among those with public insurance and of non-White race. Despite locally high vaccine acceptance, additional efforts are needed to address barriers and reduce disparities in COVID-19 vaccination within the pregnant population.

Health Care Delivery Site- and Patient-Level Factors Associated With COVID-19 Primary Vaccine Series Completion in a National Network of Community Health Centers.

Objectives. To assess multilevel factors associated with variation in COVID-19 vaccination rates in a US network of community health centers. Methods. Using multilevel logistic regression with electronic health record data from ADVANCE (Accelerating Data Value Across a National Community Health Center Network; January 1, 2022-December 31, 2022), we assessed associations between health care delivery site-level (n = 1219) and patient-level (n = 1 864 007) characteristics and COVID-19 primary vaccine series uptake. Results. A total of 1 337 440 patients completed the COVID-19 primary vaccine series. Health care delivery site characteristics were significantly associated with lower series completion rates, including being located in non-Medicaid expansion states and isolated or rural communities and serving fewer patients. Patient characteristics associated with significantly lower likelihood of completing the vaccine series included being Black/African American or American Indian/Alaska Native (vs White), younger age, lower income, being uninsured or publicly insured (vs using private insurance), and having fewer visits. Conclusions. Both health care delivery site- and patient-level factors were significantly associated with lower COVID-19 vaccine uptake. Community health centers have been a critical resource for vaccination during the pandemic. (Am J Public Health. 2024;114(11):1242-1251. https://doi.org/10.2105/AJPH.2024.307773).

Effectiveness of the original monovalent mRNA COVID-19 vaccination series against hospitalization for COVID-19-associated venous thromboembolism.

COVID-19 is a strong risk factor for venous thromboembolism (VTE). Few studies have evaluated the effectiveness of COVID-19 vaccination in preventing hospitalization for COVID-19 with VTE. Adults hospitalized at 21 sites between March 2021 and October 2022 with symptoms of acute respiratory illness were assessed for COVID-19, completion of the original monovalent mRNA COVID-19 vaccination series, and VTE. Prevalence of VTE was compared between unvaccinated and vaccinated patients with COVID-19. Vaccine effectiveness in preventing COVID-19 hospitalization with VTE was calculated using a test negative design. Vaccine effectiveness was also stratified by predominant circulating SARS-CoV-2 variant. Among 18,811 patients (median age 63 [IQR:50-73], 49% women, 59% non-Hispanic White, 20% non-Hispanic Black, 14% Hispanic, and median of 2 comorbid conditions [IQR:1-3]), 9,792 were admitted with COVID-19 (44% vaccinated) and 9,019 were test-negative controls (73% vaccinated). Among patients with COVID-19, 601 were diagnosed with VTE by hospital day 28, of whom 170 were vaccinated. VTE was more common among unvaccinated than vaccinated COVID-19 patients (7.8% versus 4.0%; p=0.001). Vaccine effectiveness against COVID-19 hospitalization with VTE was 84% (95% CI: 80-87%) overall. Vaccine effectiveness stratified by predominant circulating variant was 88% (73-95%) for alpha, 93% (90-95%) for delta, and 68% (58-76%) for omicron variants. Vaccination with the original monovalent mRNA series was associated with a decrease in COVID-19 hospitalization with VTE, though data detailing prior history of VTE and use of anticoagulation were not available. These findings will inform risk-benefit considerations for those considering vaccination.

Generational Factors Associated with SARS-CoV-2 Vaccine Completion for Americans of Mexican Decent Living along the United States-Mexico Border Region.

Background: SARS-CoV-2 vaccine uptake variation remains a significant barrier to overcoming the spread of COVID-19. Individual beliefs/attitudes about the SARS-CoV-2 vaccine vary significantly across generations due to personal experiences, access to accurate information, education levels, political beliefs, and trust in healthcare systems. Methods: This analysis used data from the baseline visit of Project 2VIDA!, a cohort of Americans of Mexican descent (AoDM) and African American individuals (n = 1052) in San Diego, CA, along the U.S.-Mexico border region. The survey assessed sociodemographics, healthcare access, socioeconomic factors, and trust in public health information/SARS-CoV-2 prevention. We conducted a logistic regression involving AoDM individuals to identify generational factors associated with completing the SARS-CoV-2 vaccine series. Results: The results of the logistic regression analysis revealed that Generation X (OR = 0.52, 95% CI = 0.33-0.82), Millennials (OR = 0.24, 95% CI = 0.14-0.41), and Generation Z (OR = 0.10, 95% CI = 0.05-0.22) were less likely to complete the SARS-CoV-2 vaccine series when compared to Baby Boomers and the Silent Generation. Conclusions: Participants with a history of SARS-CoV-2 testing and trust in the SARS-CoV-2 vaccine were significantly more likely to complete the SARS-CoV-2 vaccine series. Efforts to address vaccine series completion should be tailored to the specific concerns and motivations of different age groups.

The Effectiveness of Interventions Targeting Adolescents in HPV Vaccination-A Scoping Review.

Adolescents are the target group for HPV vaccination. Studies that examine factors influencing acceptability among adolescents and interventions aimed at improving knowledge, attitudes, perceptions, intentions, and, most importantly, vaccination rates are less common than those addressing parents or healthcare professionals. The specialized literature was searched for studies evaluating the impact of various interventions on adolescents. In the final analysis, 41 studies were included (35 original studies and 6 reviews). Educational interventions increased adolescents' knowledge scores in the selected studies. Peer education proved highly effective in rapidly and significantly improving knowledge about HPV. Additionally, multicomponent interventions generated awareness and knowledge that persisted for months after the interventions. HPV vaccine uptake increased following educational interventions in 11 out of the 14 studies that evaluated this outcome; studies presenting multicomponent interventions also proved effective in improving vaccination rates. Higher HPV vaccine series completion was reported following a reminder system strategy. Interventions directed at adolescents, combined with strategies involving parents and healthcare professionals, can play an important role in improving HPV vaccination rates. Educated adolescents must be involved in decisions about their own health and can be a valuable source of information for their peers and parents.

Abstract A146: Racial/ethnic differences in the relationship between human papillomavirus vaccination status and up-to-date Papanicolaou tests

Abstract Background: Human papillomavirus (HPV) vaccination and routine Papanicolaou (Pap) testing can prevent morbidity and mortality associated with cervical cancer (CC). Research suggests women who have initiated and completed the HPV vaccine are more likely to have an up-to-date Pap test than women who are unvaccinated against HPV. Limited research has focused on whether the association between HPV vaccination and Pap testing varies based on the number of HPV vaccine doses received across racial/ethnic groups. Methods: We conducted a cross-sectional analysis of 2018 – 2022 Behavioral Risk Factor Surveillance System data to investigate the relationship between HPV vaccination status and having an up-to-date Pap test by race/ethnicity. Based on the Advisory Committee on Immunization Practices’ (ACIP) guidelines, women who received 0 doses of the HPV vaccine were unvaccinated, women who received 1 or 2 doses initiated the vaccine series, and women who received 3 doses completed the HPV vaccine series. Based on the United States Preventive Services Task Force guidelines, women were considered to have an up-to-date Pap test if they reported having one within the past 3 years. We used weighted multivariable logistic regression models to examine the association. Results: Most women (n = 14,615) were unvaccinated (82.9%) and had an up-to- date Pap test (75.5%). Non-Hispanic White (NHW) women had the highest rate of HPV vaccine series completion (11.8%), followed by non-Hispanic Other (NHO) women (11.2%), non- Hispanic Black (NHB) women (8.6%), and Hispanic women (8.3%). NHW women also had the highest rate of up-to-date Pap test (78.8%). NHB women had the second highest rate (77.6%), followed by Hispanic women (67.8%), and NHO women (66.4%). In adjusted analyses, NHO women were 34% less likely to have an up-to-date Pap test than NHW women (OR, 0.66; 95% CI: 0.51-0.86). Compared to unvaccinated women, those who completed and initiated the HPV vaccine series were more likely to have an up-to-date Pap test (initiated: OR: 1.40, 95% CI: 1.04-1.87; completed: OR:1.77, 95% CI: 1.35-2.34). NHB and NHO women who initiated the HPV vaccine series were more likely to have an up-to-date Pap test (NHB: OR: 3.37, 95% CI: 1.65-6.85; NHO: OR: 3.21, 95% CI: 1.73-5.95). NHW women who completed the HPV vaccine series were more likely to have an up-to-date Pap test (OR: 2.19, 95% CI: 1.55-3.08). Conclusion: NHB and NHO women who initiated the HPV vaccine series were three times as likely to have an up-to-date Pap test; NHW women who have completed the HPV vaccine series were twice as likely to receive an up-to-date Pap test. Women who do not receive Pap tests or the HPV vaccine miss important CC prevention opportunities. Thus, relevant stakeholders should aim to improve HPV vaccination rates; doing so could potentially enhance Pap test adherence simultaneously. This may be especially important for NHB and NHO women as they have lower rates of Pap test adherence and HPV vaccine series completion. Citation Format: Elinita Pollard, Meng-Han Tsai, Minjee Lee, Alice W. Lee, Mary A. Gerend. Racial/ethnic differences in the relationship between human papillomavirus vaccination status and up-to-date Papanicolaou tests [abstract]. In: Proceedings of the 17th AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2024 Sep 21-24; Los Angeles, CA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2024;33(9 Suppl):Abstract nr A146.

Human Papillomavirus Vaccination Coverage Among Adolescent Girls Aged 13-17 Years - U.S.-Affiliated Pacific Islands, 2013-2023.

Worldwide, cervical cancer is the fourth most common cancer among women, and the World Health Organization (WHO) Western Pacific Region, where the U.S.-affiliated Pacific Islands (USAPI) are located, accounts for one quarter of all estimated cases. Human papillomavirus (HPV) vaccines are recommended at age 11-12 years to prevent most cervical cancers. HPV vaccines were introduced across USAPI during 2007-2016, predominantly provided through school-located vaccination programs. Retrospective analysis using data from jurisdictional immunization information systems was used to estimate vaccination coverage among adolescent girls as of the last day of each calendar year during 2013-2023. This analysis measured progress toward the WHO 2030 vaccination coverage goal of ≥90% completion of the HPV vaccination series among girls by age 15 years. As of December 2023, initiation of the HPV vaccination series among adolescent girls aged 13-17 years ranged from 58.0% in Palau to 97.2% in the Northern Mariana Islands, and HPV vaccination series completion coverage ranged from 43.4% in Palau to 91.8% in the Northern Mariana Islands. HPV vaccination series completion coverage is >90% in the Northern Mariana Islands and is on track to meet WHO goals by 2030 in American Samoa. Assessment of adolescent vaccination coverage can help immunization programs monitor progress toward regional goals and identify populations and areas with low coverage. Implementing evidence-based strategies to increase vaccine access and coverage would benefit jurisdictions with lagging coverage.

Barriers to HPV vaccine series completion among a predominantly hispanic border population: a mixed method evaluation

BackgroundHuman Papillomavirus (HPV) infections are the most common sexually transmitted infections in the United States. The HPV vaccine is a vital tool to prevent against several cancers, namely cervical cancer. Unfortunately, the uptake of the HPV vaccine among Hispanics is relatively low. Some barriers to uptake include language barriers, cultural taboos, and cost.PurposeThis study aims to explore barriers to HPV vaccination in a predominantly Hispanic US-Mexico border county between June 2015 and March 2018.MethodsA mixed-method approach was used to analyze covariates associated with HPV vaccine uptake and to evaluate barriers to HPV vaccination from participant follow-up calls or reminder notes.ResultsThe total number of participants was 1,787. Young adults were less likely to complete the vaccination series than those aged 9-17, while individuals born in Mexico were more likely to do so. Failure to contact was the most common barrier (n=1,801, 86.42%), followed by scheduling concerns (n=99, 4.5%), being ineligible (74, 3.55%), completing series outside of the program (40, 1.92%), having medical concerns (36, 1.73%), and other reasons (34, 1.63%).ConclusionWe predominantly identified structural barriers and various health-related determinants regarding healthcare access and quality.

Novel RNA-nanoparticle vaccine for the treatment of early melanoma recurrence following adjuvant anti-PD-1 antibody therapy.

TPS9609 Background: Melanoma is a major public health concern with an anticipated increase in prevalence and incidence in the coming years. Early detection and surgical management remain the mainstay of treatment of early-stage disease and use of adjuvant immunotherapy has improved outcomes for patients with more aggressive (IIB-IIC) local disease or those with lymph node involvement (IIIA-IIID). Based on the tolerability and efficacy across subjects with both BRAF mutated and wildtype melanoma anti-PD1 (aPD1) therapy with either nivolumab or pembrolizumab are considered first line treatment in this setting. Adjuvant aPD1 therapy has significant improvement in relapse free survival (RFS) yet 25-30% of subjects will have disease recurrence within 1 year of surgery. When disease recurs, the response rate to immunotherapy is significantly reduced, re-challenged with aPD1 therapy has shown an Objective Response Rate (ORR) of zero and a marginally better response to CTLA-4 blockade. Novel strategies are needed for this at-risk population with early aPD1 resistance. To address this need we have developed a novel multi-lamellar lipid-nanoparticle complexed with total-tumor derived mRNA administered intravenously to restore responsiveness to aPD1 through reprogramming the tumor microenvironment (TME) bridging an innate and adaptive immune response. We have designed a clinical trial in which patients who progress on while on aPD1 therapy or within 6 months of therapy will have tumor sampled and a personalized lipid-nanoparticle vaccine generated. This vaccine is then administered IV for a total of 3 doses spanning 6 weeks to reprogram the TME and restore response to aPD1 which will be resumed on completion of vaccine series. This phase I study will assess initial feasibility and safety of vaccine generation, utilize ctDNA surveillance as early detection of adjuvant failure, and provide essential biologic information on immunotherapy resistance to aPD1 therapy. Methods: We have designed a modified 3+3 phase I clinical trial that will enroll subjects who have evidence of progressive disease (PD) by ctDNA and/or RECIST 1.1 criteria while receiving adjuvant aPD1 therapy, or those who progress within 6 months of completion of treatment for stage IIB-IIID melanoma. The goal of this study is to assess safety, tolerability, and feasibility of tumor specific RNA-LPs. Important biological correlates will also be collected and analyzed including tumor tissue sampling at initial time of checkpoint resistance and following vaccination series to identify key changes to the TME and tumor induced by lipid-nanoparticle vaccine administration. Clinical trial information: NCT05264974 .

Trends in human papilloma virus vaccination uptake by sex and race/ethnicity among US adolescents and young adults, 2011-2020.

10519 Background: High-risk strains of human papillomavirus (HPV) are associated with a variety of oral and anogenital cancers, many of which are preventable through HPV vaccination. In the US, completion of an HPV vaccination series is recommended for all individuals from age 9 through 26; however, national trends in HPV vaccination uptake across sex and racial/ethnic groups over the past decade are not well described. Methods: We analyzed data from the National Health and Nutrition Examination Survey across 4 survey cycles spanning January 2011 to March 2020. We used univariate logistic regression to evaluate temporal trends in HPV vaccination uptake across sex and racial/ethnic strata, with the midpoint of each survey cycle modeled as a continuous independent variable. Vaccination uptake was defined as self/parent-reported receipt of ≥ 1 dose of an HPV vaccine series (estimates for 2 and 3 doses were unreliable due to recall bias and missing data). All estimates incorporated appropriate survey weights to be representative of the US population. Results: We identified 10,927 participants representing 70,066,252 individuals: mean age 17.4 years, 48.8% male, 54.9% White. Between 2011-March 2020, overall HPV vaccination uptake steadily increased from 23.3% to 43.0% ( P trend < 0.001; Table). HPV vaccination rates improved from 37.7% to 49.4% among females ( P trend < 0.001) and from 7.8% to 36.4% among males ( P trend < 0.001). HPV vaccination uptake increased similarly across all racial/ethnic strata by approximately 20%, with White individuals achieving the greatest vaccination uptake (45.5%) by March 2020. Conclusions: Among US adolescents and young adults, HPV vaccination uptake rose by ~20% overall and across all racial/ethnic groups. HPV vaccination uptake accelerated the most among males but still lags behind females, perhaps because routine vaccination wasn’t recommended for males until 2011, 5 years after it had been recommended for females. [Table: see text]

Human papillomavirus vaccine coverage among immigrant adolescents in Alberta: a population-based cohort study.

Little is known about human papillomavirus (HPV) vaccination among immigrant children in Canada. We conducted a study in Alberta, Canada to assess HPV vaccine coverage among school-aged immigrant children compared with non-immigrant children. This cohort study analysed population-based linked administrative health data to measure HPV vaccine coverage for 346749 school-aged children, including 31656 immigrants. Coverage was examined at 12y of age from 2008 to 2018 for females, and from 2014 to 2018 for males and both sexes combined; vaccine series completion was considered receipt of three doses, with initiation (one or more dose) as a supplementary analysis. Multivariable logistic regression examined the association of vaccine coverage with migration status, adjusting for sociodemographic variables. Between 2014 and 2018, HPV vaccination coverage among immigrant children at age 12y was significantly higher (52.58%) compared with non-immigrant children (47.41%). After controlling for place of residence, income quintile, biological sex and year, immigrant children had 1.10 greater odds (95% confidence interval 1.07 to 1.14) of receiving three doses of HPV vaccine compared with non-immigrant children. Immigrants from Asia and Africa had the highest coverage (60.25-68.78%), while immigrants from North America, Oceania and South America had the lowest coverage (39.97-48.36%). It is encouraging that immigrant children had higher HPV vaccine coverage compared with non-immigrants. Among immigrants, routine immunization promotion strategies should be tailored based on the country of origin.

Immunogenicity of Monovalent mRNA-1273 and BNT162b2 Vaccines in Children

The messenger RNA (mRNA)-based coronavirus disease 2019 vaccines approved for use in children <5 years of age have different antigen doses and administration schedules that could affect vaccine immunogenicity and effectiveness. We sought to compare the strength and breadth of serum binding and neutralizing antibodies to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) elicited by monovalent mRNA-based coronavirus disease 2019 vaccines in young children. We conducted a prospective cohort study of children 6 months to 4 years of age who completed primary series vaccination with monovalent mRNA-1273 or BNT162b2 vaccines. Serum was collected 1 month after primary vaccine series completion for the measurement of SARS-CoV-2-specific humoral immune responses, including antibody binding responses to Spike proteins from an ancestral strain (D614G) and major variants of SARS-CoV-2 and antibody neutralizing activity against D614G and Omicronsubvariants (BA.1, BA.4/5). Of 75 participants, 40 (53%) received mRNA-1273 and 35 (47%) received BNT162b2. Children receiving either primary vaccine series developed robust and broad SARS-CoV-2-specific binding and neutralizing antibodies, including to Omicronsubvariants. Children with a previous history of SARS-CoV-2 infection developed significantly higher antibody binding responses and neutralization titers to Omicronsubvariants, which is consistent with the occurrence of identified infections during the circulation of Omicronsubvariants in the region. Monovalent mRNA-1273 and BNT162b2 elicited similar antibody responses 1 month after vaccination in young children. In addition, previous infection significantly enhanced the strength of antibody responses to Omicronsubvariants. The authors of future studies should evaluate incorporation of these vaccines into the standard childhood immunization schedule.

HPV Multilevel Intervention Strategies Targeting Immunization in Community Settings (HPV MISTICS): Study protocol for a hybrid 1 stepped-wedge cluster randomized trial

BackgroundThis protocol paper describes the overall design for HPV MISTICS, a multilevel intervention to increase human papillomavirus (HPV) vaccination initiation and completion rates among adolescents aged 11–17. MethodsWe will conduct a hybrid type 1 implementation-effectiveness trial using a stepped-wedge cluster randomized trial in eight federally qualified health centers (FQHCs) in Florida. Intervention components target three levels: system, providers, and parents. Outcomes will be assessed using quantitative (e.g., vaccination data, survey data) and qualitative methods (e.g., staff and parent interviews). We expect to quantify changes in HPV vaccine series initiation and completion rates for adolescents ages 11–17 in the eight FQHCs. We have hypothesized a 20-percentage point increase in HPV vaccine series initiation and a 10-percentage point increase in series completion. We also anticipate being able to explore factors at the system, provider, and patient levels as potential covariates. Implementation outcomes, barriers, and facilitators identified in the study will help characterize the implementation process and inform potential future intervention scale-up. ResultsThe project is ongoing; effectiveness and implementation outcomes will be determined following project completion. ConclusionsFindings will provide evidence of an equity-informed research design and implementation procedures that could help improve HPV vaccination rates in similar health systems.Clinical trials identifier:NCT05677360 (date registered: 2022-12-22); https://clinicaltrials.gov/study/NCT05677360?lead=Moffitt%20Cancer%20Center%20&aggFilters=status:rec&page=2&rank=17

Barriers to cervical cancer prevention in a safety net clinic: gaps in HPV vaccine provider recommendation and series completion among Ob/Gyn patients.

The primary objective of this study was to evaluate patients' knowledge regarding HPV vaccination and vaccine uptake in a diverse patient population. The secondary objective was to evaluate factors influencing the decision to vaccinate, potential barriers to vaccination, and to assess whether HPV vaccines were offered to or discussed with eligible patients in a safety net Obstetrics and Gynecology (Ob/Gyn) clinic. A 28-item survey was developed using Likert scale survey questions to assess patient agreement with statements regarding HPV and the vaccine. The surveys were administered to patients in the Ob/Gyn outpatient clinics from May 2021 through September 2022. Additionally, pharmacy data were reviewed and chart review was performed as a quality improvement initiative to assess the impact of expanded HPV vaccine eligibility to patients with private insurance on vaccine uptake. Descriptive statistics were performed. 304 patients completed surveys from May 2021 through September 2022. The median age of respondents was 32 (range 18-80). 16 (5%) were Non-Hispanic White, 124 (41%) were Hispanic White, 58 (19%) were Non-Hispanic Black, 6 (2%) were Hispanic Black, 29 (9.5%) were Haitian, 44 (14%) were Hispanic Other, 7 (2%) were Non-Hispanic Other, 20 (6.6%) did not respond. 45 (14%) patients were uninsured. Many patients (62%) reported that a physician had never discussed HPV vaccination with them. Seventy nine percent of patients reported they had never received the HPV vaccine, and 69% of patients reported that lack of a medical provider recommendation was a major barrier. Among patients to whom HPV vaccination had been recommended, 57% reported that the vaccine was not available the same day in clinic. Our study demonstrated that many patients never had a provider discuss HPV vaccination with them and never received the HPV vaccine. Additionally, amongst those who did initiate HPV vaccination, completion of the series remains a key barrier. Ensuring that providers discuss HPV vaccination and that patients receive HPV vaccines, along with expanding access to and convenience of HPV vaccination are critical aspects of preventing cervical cancer.