Antibody Responses to 3rd Dose mRNA Vaccines in Nursing Home and Assisted Living Residents

A comparison of SARS-CoV-2 wild-type and the beta variant virus neutralization capacity between 2 and 3 mRNA vaccine series in nursing home residents, and between nursing home and assisted living residents strongly supports 3rd dose vaccine recommendations, and equivalent polices for nursing homes and assisted living settings. Findings suggest that residents mount a robust humoral response to a 3rd mRNA vaccination, and have greater neuralization capacity compared to a 2 dose series.

Human Papillomavirus Vaccine Efficacy and Effectiveness against Cancer

Human papillomavirus (HPV) is the most common sexually transmitted infection, with 15 HPV types related to cervical, anal, oropharyngeal, penile, vulvar, and vaginal cancers. However, cervical cancer remains one of the most common cancers in women, especially in developing countries. Three HPV vaccines have been licensed: bivalent (Cervarix, GSK, Rixensart, Belgium), quadrivalent (Merck, Sharp & Dome (Merck & Co, Whitehouse Station, NJ, USA)), and nonavalent (Merck, Sharp & Dome (Merck & Co, Whitehouse Station, NJ, USA)). The current HPV vaccine recommendations apply to 9 years old and above through the age of 26 years and adults aged 27–45 years who might be at risk of new HPV infection and benefit from vaccination. The primary target population for HPV vaccination recommended by the WHO is girls aged 9–14 years, prior to their becoming sexually active, to undergo a two-dose schedule and girls ≥ 15 years of age, to undergo a three-dose schedule. Safety data for HPV vaccines have indicated that they are safe. The most common adverse side-effect was local symptoms. HPV vaccines are highly immunogenic. The efficacy and effectiveness of vaccines has been remarkably high among young women who were HPV seronegative before vaccination. Vaccine efficacy was lower among women regardless of HPV DNA when vaccinated and among adult women. Comparisons of the efficacy of bivalent, quadrivalent, and nonavalent vaccines against HPV 16/18 showed that they are similar. However, the nonavalent vaccine can provide additional protection against HPV 31/33/45/52/58. In a real-world setting, the notable decrease of HPV 6/11/16/18 among vaccinated women compared with unvaccinated women shows the vaccine to be highly effective. Moreover, the direct effect of the nonavalent vaccine with the cross-protection of bivalent and quadrivalent vaccines results in the reduction of HPV 6/11/16/18/31/33/45/52/58. HPV vaccination has been shown to provide herd protection as well. Two-dose HPV vaccine schedules showed no difference in seroconversion from three-dose schedules. However, the use of a single-dose HPV vaccination schedule remains controversial. For males, the quadrivalent HPV vaccine possibly reduces the incidence of external genital lesions and persistent infection with HPV 6/11/16/18. Evidence regarding the efficacy and risk of HPV vaccination and HIV infection remains limited. HPV vaccination has been shown to be highly effective against oral HPV type 16/18 infection, with a significant percentage of participants developing IgG antibodies in the oral fluid post vaccination. However, the vaccines’ effectiveness in reducing the incidence of and mortality rates from HPV-related head and neck cancers should be observed in the long term. In anal infections and anal intraepithelial neoplasia, the vaccines demonstrate high efficacy. While HPV vaccines are very effective, screening for related cancers, as per guidelines, is still recommended.

Towards Ending Immunization Inequity

Vaccine-preventable diseases (VPD) are responsible for a significant portion of mortality across the life course in both low-income countries and in medium- and high-income countries. Yet, countries are consistently below the adult influenza vaccination targets, with rates in recent times even falling in some areas. (1) The study Towards Ending Immunization Inequity seeks to understand the various factors that contribute to the accessibility and effectiveness of vaccine-related messages and campaigns including the effects of social determinants, with the knowledge that these opportunities for communication represent a unique policy lever to improving uptake rates of vaccination in the most at-risk communities. (2) To address this knowledge gap, a 3-phase mixed-methods study was conducted including a preliminary scan of existing vaccine schedules and NITAG recommendations, focus groups and a cross-sectional survey. (3) Study results indicated that social determinants play a key role in an individual’s knowledge of vaccine-related information including types of vaccines available, vaccination gateways, vaccine recommendations and vaccine safety. (4) However, knowing that social determinants can influence uptake rates does not readily create opportunities and entry points for governments to implement tangible actions. An accessible entry point to reducing and ending immunization inequity is through changes in public health messaging to reach those who are currently unreachable.

06. United States Healthcare Provider Preferences for Adult Pneumococcal Vaccine Recommendations

Background Pneumococcal vaccine recommendations for US adults are complex, varying by age and underlying conditions, and include both 23-valent polysaccharide vaccine (PPSV23) and 13-valent pneumococcal conjugate vaccine. The Advisory Committee on Immunization Practices (ACIP) will vote on new recommendations in October after the 15- (PCV15) and 20-valent (PCV20) conjugate vaccines are approved. Stakeholder acceptability is part of ACIP’s evidence to recommendation framework, but few data are available on health care providers’ (HCPs) preferences for potential recommendations. Methods 752 HCPs (300 physicians, 150 nurse practitioners, 150 physician assistants, & 152 pharmacists) were surveyed. Object case best-worst scaling (BWS) was used to elicit preferences for hypothetical recommendations for 1) adults 19-64 years with chronic conditions and 2) immunocompetent adults ≥65 years. Presented recommendations included combinations of PCV15/PCV20 either as routine or after shared clinical decision making (SCDM), and PPSV23 as routine, SCDM, or no recommendation. Following BWS, HCPs were asked to assume ACIP was considering implementing both of their preferred recommendations for the age/risk groups. HCPs were then given the opportunity to change their selections and propose recommendations not included in the BWS exercise. Additional information was collected using conventional survey items. Results Routine use of higher-valent PCVs in sequence with PPSV23 was most often preferred for both adults 19-64 with chronic conditions (40%) and immunocompetent adults ≥65 (49%) when elicited separately for each age/risk group. Most respondents (63%) revised their recommendations after considering implementation, which resulted in most (59%) favoring recommendations harmonized across the age/risk groups, and 75% favoring routine use of PCV15 or PCV20 among immunocompetent adults ≥65. When asked directly, HCPs generally approved of the idea of simplifying adult pneumococcal vaccine recommendations, harmonizing the interval between vaccines, and lowering the cutoff for age-based recommendations below 65 years. Conclusion US HCPs generally prefer simplification of the adult pneumococcal recommendation, favoring broad routine use of both higher-valent PCVs and PPSV23. Disclosures Jeffrey Vietri, PhD, Pfizer Inc (Employee, Shareholder) Kelley Meyers, PhD, RTI Health Solutions (Independent Contractor) Christine Poulos, PhD, Pfizer Inc (Other Financial or Material Support, Employee of RTI-HS, which received funds from Pfizer to conduct the study) Erica Chilson, PharmD, Pfizer, Inc (Employee, Shareholder) Vincenza Snow, MD, Pfizer Vaccines (Employee)

1325. Recalibrating Estimates of Pneumococcal Disease in Hospitalized Canadian adults from 2010 to 2017 with Use of an Extended Spectrum Serotype-specific Urine Antigen Detection

Background Pneumococcal vaccine recommendations in Canada include both age- and risk-based guidance. This study aimed to describe the burden of vaccine-preventable pneumococcal community acquired pneumonia (pCAP) and invasive pneumococcal disease (IPD) by age in hospitalized adults. Methods Active surveillance for all-cause CAP and IPD in hospitalized adults was performed from 2010 to 2017, including laboratory results, patient demographics, and outcomes. Streptococcus pneumoniae was detected using blood and sputum culture, or urine antigen detection (UAD). Serotype was assigned using Quellung reaction, PCR, or serotype-specific UADs spanning the 24 serotypes in PCV13 and PPV23 vaccines. Data were categorized by age (16-49, 50-64, 65+, and 50+ years) and over time. Results 11129 ACP cases and 216 cases of IPD (non-CAP) were identified. A laboratory test for S. pneumoniae was performed in 8912 of ACP cases, identifying 1264 (14.2%) as pCAP. Compared to non-pCAP, pCAP cases were more likely to be admitted to intensive care units and require mechanical ventilation. These serious outcomes, as well as mortality, were more prominent in bacteremic pCAP and IPD. Risk factors for death in pCAP included aged 75+ years, immune compromising conditions, and BMI < 18.5. When categorized by age, the proportion of individuals aged 65+ years for pCAP and IPD was 49.8% and 48.6%, and the 50-64 year age cohort represented 31.3% and 29.9%, respectively. The contributions of PCV13 and PPV23 serotypes remained relatively stable over time, and overall represented 57.6% and 90.9% for pCAP, and 35.0% and 72.0% for IPD, respectively. Conclusion Seven years following infant PCV13 immunization programs in Canada, PCV13 and PPV23 serotypes in pCAP and IPD remained predominant causes of pneumococcal disease. Serious outcomes were particularly evident in adults 50+, suggesting pneumococcal vaccines should be encouraged in this age group. Disclosures Jason J. LeBlanc, PhD, FCCM, D[ABMM], GSK (Research Grant or Support)Merck (Grant/Research Support)Pfizer (Grant/Research Support) Todd F Hatchette, MD, GSK (Grant/Research Support)Pfizer (Grant/Research Support) Melissa K. Andrew, MD, PhD, GSK (Grant/Research Support)Pfizer (Grant/Research Support, Advisor or Review Panel member)Sanofi (Consultant, Grant/Research Support, Advisor or Review Panel member)Seqirus (Advisor or Review Panel member) Allison McGeer, MSc,MD,FRCPC,FSHEA, GlaxoSmithKline (Advisor or Review Panel member)Merck (Advisor or Review Panel member, Research Grant or Support)Pfizer (Grant/Research Support, Scientific Research Study Investigator, Advisor or Review Panel member) Louis Valiquette, MD, M.Sc., Cubist (Consultant)GSK (Grant/Research Support)Merck (Consultant)Optimer (Consultant)Pfizer (Grant/Research Support) Shelly McNeil, FRCPC, MD, GSK (Grant/Research Support)Pfizer (Grant/Research Support)Sinofi Pasteur (Grant/Research Support)

Examining Associations between Knowledge and Vaccine Uptake Using the Human Papillomavirus Knowledge Questionnaire (HPV-KQ)

Objectives: Understanding the relationship between human papillomavirus (HPV) knowledge and vaccination behavior is important to inform public health interventions, yet few validated HPV knowledge scales exist. This study describes development of the Human Papillomavirus Knowledge Questionnaire (HPV-KQ) and its validation with parents residing in the southern United States (US). Methods: Drawing on previously published measures, we developed the 13-item HPV-KQ and administered the scale via Web-based survey to parents (N=1105) of adolescents ages 9 to 17 years. Dimensionality, internal consistency, model fit, and predictive validity were assessed. Results: The scale was bidimensional. One factor captured general HPV knowledge, and the second factor captured perceptions of gender differences in HPV infection and vaccine recommendations. The 13-item scale and 2-factor solution displayed strong internal consistency and good model fit. Parents of vaccinated adolescents scored higher on the 13-item HPV-KQ (Mean = 8.56) than parents of unvaccinated adolescents (Mean = 6.43) (p < .001). In regression models, controlling for key covariates, parents' performance on the HPV-KQ predicted adolescent HPV vaccination (p < .001). Conclusions: Evaluation indicates the HPV-KQ is a reliable and valid tool for measuring knowledge of HPV and the HPV vaccine among parents residing in the southern US. We recommend further efforts to validate the scale with other populations.

Summary of the National Advisory Committee on Immunization (NACI) Seasonal Influenza Vaccine Statement for 2021–2022

Background: Several influenza vaccines are authorized in Canada and the evidence on influenza immunization is continually evolving. The National Advisory Committee on Immunization (NACI) provides recommendations regarding the use of seasonal influenza vaccines annually to the Public Health Agency of Canada (PHAC). Objective: To summarize NACI recommendations regarding the use of seasonal influenza vaccines for 2021–2022 and to highlight new recommendations. Methods: Annual influenza vaccine recommendations are developed by NACI's Influenza Working Group for consideration and approval by NACI. The development of the recommendations is based on the NACI evidence-based process. Results: The following new recommendations were made: 1) Influvac® Tetra may be considered as an option among the standard dose quadrivalent inactivated influenza vaccines (IIV4-SD) offered to adults and children three years of age and older; 2) Fluzone High Dose Quadrivalent (IIV4-HD) may be considered an option for individuals 65 years of age and older who are currently recommended to receive Fluzone® High Dose (trivalent); and 3) Flucelvax® Quad may be considered amongst the quadrivalent influenza vaccines offered to adults and children nine years of age and older for annual influenza immunization. Guidance for use of influenza immunizations during the coronavirus disease 2019 pandemic is also highlighted. Conclusion: NACI continues to recommend that an age-appropriate influenza vaccine should be offered annually to anyone six months of age and older who does not have contraindications to the vaccine. Vaccination should be offered as a priority to people at high risk of influenza-related complications or hospitalization, people capable of transmitting influenza to those at high risk of complications, and others as indicated.