Cervical Intraepithelial Neoplasia Rates in British Columbia Women: A Population-Level Data Linkage Evaluation of the School-Based HPV Immunization Program.

BACKGROUND: To understand real-world human papillomavirus (HPV) vaccine impact, continuous evaluation using population-based data is critical. We evaluated the early impact of the school-based HPV immunization program on cervical dysplasia in women in British Columbia, Canada. METHODS: Data linkage was performed using records from provincial cervical screening and immunization registries. Precancerous outcomes were compared between unvaccinated and HPV-vaccinated women born 1994-2005. Incidence rate, relative rate (RR), and vaccine effectiveness (VE), using unadjusted and adjusted Poisson regression of cytology (HSIL) and histopathology (CIN2, CIN3, and CIN2+) outcomes, were compared across vaccination status groups. RESULTS: Women who received a complete series of vaccine on schedule between age 9 and 14 years had an adjusted RR = 0.42 (95% confidence interval [CI], 0.31-0.57) for CIN2+ over 7 years of follow-up compared to unvaccinated women, resulting in a VE of 57.9% (95% CI, 43.2%-69.0%). Adjusted RR for HSIL was 0.53 (95% CI, .43-.64), resulting in a VE of 47.1% (95% CI, 35.6%-56.7%). CONCLUSION: Women vaccinated against HPV have a lower incidence of cervical dysplasia compared to unvaccinated women. Immunization between 9 and 14 years of age should be encouraged. Continued program evaluation is important for measuring long-term population impact.

Immunization delivery in British Columbia: perspectives of primary care physicians.

OBJECTIVE: To explore the experiences of family physicians and pediatricians delivering immunizations, including perceived barriers and supports. DESIGN: Qualitative study using focus groups. SETTING: Ten cities throughout British Columbia. PARTICIPANTS: A total of 46 family physicians or general practitioners, 10 pediatricians, and 2 residents. METHODS: A semistructured dialogue guide was used by a trained facilitator to explore participants' experiences and views related to immunization delivery in British Columbia. Verbatim transcriptions were independently coded by 2 researchers. Key themes were analyzed and identified in an iterative manner using interpretive description. MAIN FINDINGS: Physicians highly valued vaccine delivery. Factors facilitating physician-delivered immunizations included strong beliefs in the value of vaccines and having adequate information. Identified barriers included the large time commitment and insufficient communication about program changes, new vaccines, and the adult immunization program in general. Some physicians reported good relationships with local public health, while others reported the opposite experience, and this varied by geographic location. CONCLUSION: These findings suggest that physicians are supportive of delivering vaccines. However, there are opportunities to improve the sustainability of physician-delivered immunizations. While compensation schemes remain under the purview of the provincial governments, local public health authorities can address the information needs of physicians.

Assessing sociodemographic disparities in HPV vaccine uptake among grade 6 and 9 students in the Vancouver Coastal Health region.

PURPOSE: To identify sociodemographic factors associated with HPV vaccine uptake in a universal, in-school HPV vaccination program, among grade 6 and 9 students in the regional health authority of Vancouver Coastal Health (VCH), British Columbia (BC), Canada during the 2021/22 school year. VCH operates within the southwest corner of the province of BC serving a mix of urban and rural regions. HPV vaccine is offered in school to all grade 6 students using a two-dose series, with catch up immunizations offered to students in grade 9. METHODS: We conducted a cross-sectional study of grade 6 and 9 students enrolled in VCH schools for the 2021/22 school year, who also resided within the VCH region. We modelled the associations between sociodemographic explanatory variables (individual-level and group-level) and fully vaccinated outcome using a cross-classified (non-nested) multilevel model. RESULTS: Among the 17,939 students eligible, 74 % were fully vaccinated for HPV. Immunization coverage was associated with grade, geographic area of residence, school category, social and material deprivation. We demonstrated that grade modified the association between material deprivation and being fully vaccinated. Grade 9 students, including those residing in more materially deprived neighbourhoods, had substantially higher odds (OR 2.01 [95 % CI 1.08, 3.75]) of being fully vaccinated relative to grade 6 students in the least materially deprived neighbourhoods. CONCLUSIONS: Though publicly funded HPV vaccine is offered to all students in grade 6 and 9, in a space that maximizes programmatic access, sociodemographic factors associated with under-immunized populations were identified. This information can be leveraged for strategic targeting of resources to underimmunized schools or students to mitigate impacts. The repeat offering of HPV vaccine in an older grade (grade 9 in BC) is a key programmatic strategy to reach under-immunized populations and should be complemented by other creative approaches.

Immunogenicity of 2 doses of HPV vaccine in younger adolescents vs 3 doses in young women: a randomized clinical trial.

IMPORTANCE: Global use of human papillomavirus (HPV) vaccines to prevent cervical cancer is impeded by cost. A 2-dose schedule for girls may be possible. OBJECTIVE: To determine whether mean antibody levels to HPV-16 and HPV-18 among girls receiving 2 doses was noninferior to women receiving 3 doses. DESIGN, SETTING, AND PATIENTS: Randomized, phase 3, postlicensure, multicenter, age-stratified, noninferiority immunogenicity study of 830 Canadian females from August 2007 through February 2011. Follow-up blood samples were provided by 675 participants (81%). INTERVENTION: Girls (9-13 years) were randomized 1:1 to receive 3 doses of quadrivalent HPV vaccine at 0, 2, and 6 months (n = 261) or 2 doses at 0 and 6 months (n = 259). Young women (16-26 years) received 3 doses at 0, 2, and 6 months (n = 310). Antibody levels were measured at 0, 7, 18, 24, and 36 months. MAIN OUTCOMES AND MEASURES: Primary outcome was noninferiority (95% CI, lower bound >0.5) of geometric mean titer (GMT) ratios for HPV-16 and HPV-18 for girls (2 doses) compared with young women (3 doses) 1 month after last dose. Secondary outcomes were noninferiority of GMT ratios of girls receiving 2 vs 3 doses of vaccine; and durability of noninferiority to 36 months. RESULTS: The GMT ratios were noninferior for girls (2 doses) to women (3 doses): 2.07 (95% CI, 1.62-2.65) for HPV-16 and 1.76 (95% CI, 1.41-2.19) for HPV-18. Girls (3 doses) had GMT responses 1 month after last vaccination for HPV-16 of 7736 milli-Merck units per mL (mMU/mL) (95% CI, 6651-8999) and HPV-18 of 1730 mMU/mL (95% CI, 1512-1980). The GMT ratios were noninferior for girls (2 doses) to girls (3 doses): 0.95 (95% CI, 0.73-1.23) for HPV-16 and 0.68 (95% CI, 0.54-0.85) for HPV-18. The GMT ratios for girls (2 doses) to women (3 doses) remained noninferior for all genotypes to 36 months. Antibody responses in girls were noninferior after 2 doses vs 3 doses for all 4 vaccine genotypes at month 7, but not for HPV-18 by month 24 or HPV-6 by month 36. CONCLUSIONS AND RELEVANCE: Among girls who received 2 doses of HPV vaccine 6 months apart, responses to HPV-16 and HPV-18 one month after the last dose were noninferior to those among young women who received 3 doses of the vaccine within 6 months. Because of the loss of noninferiority to some genotypes at 24 to 36 months in girls given 2 doses vs 3 doses, more data on the duration of protection are needed before reduced-dose schedules can be recommended. TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT00501137.

Uptake of Mpox vaccination among transgender people and gay, bisexual and other men who have sex with men among sexually-transmitted infection clinic clients in Vancouver, British Columbia.

OBJECTIVES: As the primary public health strategy for controlling the 2022 Mpox outbreak, it is critical to evaluate the impact of Mpox vaccination campaigns for transgender people and gay, bisexual and other men who have sex with men (T/GBM). We measured vaccine uptake and associated factors among T/GBM clients of an urban STI clinic in British Columbia (BC). METHODS: We conducted a cross-sectional online survey between August 8-22, 2022 of clients who had attended the STI clinic, 5-7 weeks following the first-dose Mpox vaccination campaign in BC. We drew on a systematic review of factors associated with vaccine uptake to develop survey questions, and measured vaccine uptake among vaccine-eligible T/GBM. RESULTS: Overall, 51% of T/GBM had received the first dose of the vaccine. The sample (331 participants) was majority White and university educated, identified as a man and gay, 10% had trans experience, and 68% met eligibility criteria for vaccination. Among vaccine-eligible participants identifying as T/GBM, 66% had been vaccinated; being unvaccinated was more common among participants identifying as bisexual or heteroflexible/mostly straight, and who spent less time with other T/GBM. Eligible yet unvaccinated participants had lower perceived susceptibility, and reported fewer cues to action (e.g., fewer saw information promoting the vaccine), and increased constraints to vaccine access; vaccine barriers related to accessing clinics and privacy were common. The majority (85%) of those eligible and unvaccinated at time of survey were willing to receive the vaccine. CONCLUSION: In this sample of STI clinic clients, vaccine uptake among eligible T/GBM was high in the initial weeks following a Mpox vaccination campaign. However, uptake was patterned on social gradients with lower uptake among T/GBM who may be less effectively engaged by available promotion channels. We recommend early, intentional and diverse engagement of T/GBM populations in Mpox and other targeted vaccination programs.

Characterization of vaccine confidence among teachers in British Columbia, Canada: A population-based survey.

OBJECTIVES: Teachers are an important occupational group to consider when addressing vaccine confidence and uptake for school-aged children due to their proximate role within school-based immunization programs. The objectives of this study were to characterize and identify sociodemographic factors associated with vaccine confidence and describe teachers' knowledge of and perceived role in the school-based immunization program, with the aim of informing public health policy and identifying opportunities for supporting teachers in their role in school-based immunization programs. METHODS: A cross-sectional survey of elementary and secondary public-school teachers in British Columbia was completed from August to November 2020. Respondents provided sociodemographic information, as well as past vaccination experience, vaccine knowledge, and perceived role in the school-based immunization program. Vaccine confidence was measured using the Vaccine Hesitancy Scale (VHS). Characteristics associated with the VHS sub-scales 'lack of confidence in vaccines' and 'perceived risk of vaccines', were explored using ANOVA. Descriptive analysis was completed for teachers' perceived role in the immunization program. RESULTS: 5,095 surveys were included in this analysis. Overall vaccine confidence was high, with vaccine hesitancy being related to the perceived risk of vaccines rather than a lack of confidence in the effectiveness of vaccines. ANOVA found significant differences for both VHS-sub-scales based on sociodemographic factors, however, the strength of the association was generally small. High general vaccine knowledge and never having delayed or refused a vaccine in the past were associated with higher vaccine confidence. Overall, teachers reported a lack of clarity in their role within the school-based immunization program. CONCLUSIONS: This large population-based observational study of teachers highlights a number of key engagement opportunities between public health and the education sector. Using a validated scale, we found that overall, teachers are highly accepting of vaccines, and well situated as potential partners with public health to address vaccine hesitancy.

First reported outbreak of the emerging pathogen Candida auris in Canada.

BACKGROUND: Candida auris was first described in Japan in 2009 and has since been detected in over 40 countries. The yeast is concerning for multiple reasons, primarily: (1) challenges with accurate identification; (2) reported multidrug resistance; (3) published mortality rates of 30%-60%; and (4) persistence in the environment associated with human transmission. We report the emergence of a healthcare-associated cluster in the Greater Vancouver area in 2018 and describe the measures implemented to contain its transmission. METHODS: Cases were identified through passive and ring surveillance of affected wards. Positive isolates were sent to provincial and national reference laboratories for confirmation and genomic characterization. Extensive infection control measures were implemented immediately after the initial case was identified. RESULTS: Four cases were identified during the outbreak. In a 4-month period, over 700 swabs were collected in order to screen 180 contacts. Whole genome sequencing concluded that all isolates clustered together and belonged to the South Asian clade. No isolates harbored FKS gene mutations associated with resistance to echinocandins. Infection control measures, including surveillance, education, cleaning and/or disinfection, patient cohorting, isolation, and hand hygiene, effectively contained the outbreak; it was declared over within 2 months. CONCLUSIONS: The spread of C auris in healthcare facilities has not spared Canadian institutions. Our experience demonstrates that strict infection control measures combined with microbiological screening can effectively halt transmission in healthcare centers. The necessity of active prospective screening remains unclear.

Intentions of public school teachers in British Columbia, Canada to receive a COVID-19 vaccine.

BACKGROUND: To control the COVID-19 pandemic high vaccine acceptability and uptake will be needed. Teachers represent a priority population to minimize social disruption and ensure continuity in education, which is vital for the well-being and healthy development of youth during the pandemic. The objective of this analysis was to measure public school teachers' intentions to receive a COVID-19 vaccine in British Columbia (BC), Canada. METHODS: A population-wide cross-sectional online survey from August to November 2020 asked all BC public school teachers with an available email address how likely they were to receive a COVID-19 vaccine. Two multivariable logistic regression models explored separately sociodemographic and vaccine hesitancy predictors for intention to receive a COVID-19 vaccine. RESULTS: A total of 5,076 teachers participated. The majority, 89.7%, reported they were likely or very likely to accept a COVID-19 vaccine. In multivariable regression, sociodemographic predictors of intention to be vaccinated included being male, having an educational background in science or engineering, and using reliable information sources on vaccination such as public health and health care providers. Teachers who reported lower levels of vaccine hesitancy, higher general vaccine knowledge, and belief that COVID-19 was a serious illness were more likely to intend to receive a COVID-19 vaccine. CONCLUSION: A high proportion of public-school teachers in BC intend to receive a COVID-19 vaccine. Continued monitoring of vaccine intentions will be important to inform public health vaccine implementation.

Environmental detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) from medical equipment in long-term care facilities undergoing COVID-19 outbreaks.

Environmental sampling was conducted at long-term care facilities to determine the extent of surface contamination with severe acute respiratory syndrome coronavirus 2 virus. Medical equipment used throughout the facility was determined to be contaminated.

A population-based evaluation of a publicly funded, school-based HPV vaccine program in British Columbia, Canada: parental factors associated with HPV vaccine receipt.

BACKGROUND: Information on factors that influence parental decisions for actual human papillomavirus (HPV) vaccine receipt in publicly funded, school-based HPV vaccine programs for girls is limited. We report on the level of uptake of the first dose of the HPV vaccine, and determine parental factors associated with receipt of the HPV vaccine, in a publicly funded school-based HPV vaccine program in British Columbia, Canada. METHODS AND FINDINGS: All parents of girls enrolled in grade 6 during the academic year of September 2008-June 2009 in the province of British Columbia were eligible to participate. Eligible households identified through the provincial public health information system were randomly selected and those who consented completed a validated survey exploring factors associated with HPV vaccine uptake. Bivariate and multivariate analyses were conducted to calculate adjusted odds ratios to identify the factors that were associated with parents' decision to vaccinate their daughter(s) against HPV. 2,025 parents agreed to complete the survey, and 65.1% (95% confidence interval [CI] 63.1-67.1) of parents in the survey reported that their daughters received the first dose of the HPV vaccine. In the same school-based vaccine program, 88.4% (95% CI 87.1-89.7) consented to the hepatitis B vaccine, and 86.5% (95% CI 85.1-87.9) consented to the meningococcal C vaccine. The main reasons for having a daughter receive the HPV vaccine were the effectiveness of the vaccine (47.9%), advice from a physician (8.7%), and concerns about daughter's health (8.4%). The main reasons for not having a daughter receive the HPV vaccine were concerns about HPV vaccine safety (29.2%), preference to wait until the daughter is older (15.6%), and not enough information to make an informed decision (12.6%). In multivariate analysis, overall attitudes to vaccines, the impact of the HPV vaccine on sexual practices, and childhood vaccine history were predictive of parents having a daughter receive the HPV vaccine in a publicly funded school-based HPV vaccine program. By contrast, having a family with two parents, having three or more children, and having more education was associated with a decreased likelihood of having a daughter receive the HPV vaccine. CONCLUSIONS: This study is, to our knowledge, one of the first population-based assessments of factors associated with HPV vaccine uptake in a publicly funded school-based program worldwide. Policy makers need to consider that even with the removal of financial and health care barriers, parents, who are key decision makers in the uptake of this vaccine, are still hesitant to have their daughters receive the HPV vaccine, and strategies to ensure optimal HPV vaccine uptake need to be employed.

Measuring the impact of influenza vaccination on healthcare worker absenteeism in the context of a province-wide mandatory vaccinate-or-mask policy.

OBJECTIVES: In 2012, British Columbia (BC) implemented a province-wide vaccinate-or-mask influenza prevention policy for healthcare workers (HCWs) with the aim of improving HCW coverage, and reducing illness in patients and staff. We assess post-policy impacts of HCW vaccination status on their absenteeism. METHODS: We matched individual HCW payroll data from December 1, 2012 to March 31, 2017 with annually self-reported vaccination status for BC health authority employees to assess sick rates (sick time as a proportion of sick time and productive time). We modelled adjusted odds ratios (OR) of taking any sick time, relative rates (RR) of sick time taken, and predicted mean sick rates by vaccination status in influenza (December 1-March 31) and non-influenza seasons (April 1 to November 30). We used two methods to assess changes in influenza season sick rates for HCWs who had a change in their vaccination status over the five years. RESULTS: HCWs who reported 'early' vaccination (before December 1 when the policy is in effect) were less likely to take sick time (OR 0.874, 95%CI: 0.866-0.881) and took less sick time (RR 0.907, 95%CI: 0.901-0.912) in influenza season compared to HCWs who did not report vaccination; whereas HCWs who reported 'late' (between December 1 and March 31, and subject to masking until vaccinated) had similar sick rates to HCWs who did not report vaccination. These trends were also observed in non-influenza season. Influenza season sick rates were similar for HCWs that had at least one year of 'early' vaccination and one year where vaccination was not reported over the five year period. CONCLUSIONS: Overall absenteeism is lower among HCWs who report vaccination versus those who do not report. However, absenteeism behaviours appear to be influenced by individual level factors other than vaccination status.

Measuring the impact of a mandatory province-wide vaccinate-or-mask policy on healthcare worker absenteeism in British Columbia, Canada.

OBJECTIVES: Vaccinate-or-mask (VOM) policies aim to improve influenza vaccine coverage among healthcare workers (HCW) and reduce influenza-related illness among patients and staff. In 2012, British Columbia (BC) implemented a province-wide VOM influenza prevention policy. This study describes an evaluation of policy impacts on HCW absenteeism rates from before to after policy implementation. METHODS: Using payroll data from regional and provincial Health Authorities (HA), we assessed all-cause sick rates (sick time as a proportion of sick time and productive time) before (2007-2011, excluding 2009-2010) and after (2012-2017) policy implementation, and during influenza season (December 1-March 31) and non-influenza season (April 1-November 30). We used a two-part negative binomial hurdle model to calculate odds ratios (OR) of taking any sick time, relative rates (RR) of sick time taken, and predicted mean sick rates, adjusting for age group, sex, job type, job classification, HA, year and vaccine effectiveness. RESULTS: During influenza season, HCWs in the post-policy period were less likely to take any sick time (OR 0.989, 95%CI: 0.979-0.999) but had higher rates of sick time (RR 1.038, 95%CI: 1.030-1.045). However, during non-influenza season, HCWs in the post-policy period were more likely to take any sick time (OR 1.015, 95%CI: 1.008-1.022) but had lower rates of sick time (RR 0.971, 95%CI: 0.966-0.976). There was an overall increase in predicted mean sick rate from pre to post-policy in influenza season (4.392% to 4.508%) and non-influenza season (3.815% to 3.901%). CONCLUSIONS: The observed year-round increase in sick rates from pre-to-post policy was likely influenced by other factors; however, opposite trends in how HCWs took sick time in the influenza and non-influenza seasons may reflect policy influences and need further research to explore reasons for these differences.

Bridging the gap in population health for rural and Aboriginal communities: a needs assessment of public health training for rural primary care physicians.

INTRODUCTION: The literature identifies significant inequalities in the health status of rural and Aboriginal populations, compared with the general population. Providing rural primary care physicians with public health skills could help address this issue since the patterns of mortality and morbidity suggest that prevention and health promotion play an important role. However, we were unable to identify any community needs assessment for such professionals with dual skills that had been performed in Canada. METHODS: We conducted key informant interviews and focus groups in 3 rural and Aboriginal communities in British Columbia (chosen through purposive sampling). We analyzed transcripts following standard qualitative iterative methodologies to extract themes and for discussing content. RESULTS: There was broad support for a program to train primary care physicians in public health. The characteristics identified as necessary in such a physician included a long-term commitment to the community with partnership building, advocacy, communication and cultural sensitivity skills. The communities we studied identified some priority challenges, most notably that the current remuneration structure does not support physicians engaging in public health or research. CONCLUSION: There is great potential and support for the training of rural primary care practitioners in public health to improve population health and engage communities in this process.

Will Infant Hepatitis B Vaccination Protect Into Adulthood?: Extended Canadian Experience After a 2-, 4- and 6-month Immunization Schedule.

BACKGROUND: Hepatitis B virus (HBV) vaccination programs generally target infants to prevent chronic HBV infection and/or preadolescents to reduce transmission in adulthood. To assess whether infant HBV immunization can potentially accomplish both objectives, we measured residual immunity 10-16 years after vaccination in Canadian children. METHODS: A prospective, parallel group, single center study enrolled adolescents given HBV vaccine at 2, 4 and 6 months of age. Exclusion criteria included prior HBV infection and additional vaccinations. At follow-up anti-HBs testing, participants were 10-11 or 15-16 years old; those with <12 mIU/mL anti-HBs by the assay used were challenged with HBV vaccine to assess immune memory-based responsiveness. RESULTS: A total of 137 tested participants were 10-11 and 213 were 15-16 years old, respectively; none had evidence of prior HBV infection. At baseline, 78% of younger and 64% of older participants had <12 mIU/mL anti-HBs (P = 0.006) and were challenged with vaccine: 103/106 (97.2%) younger and 123/135 (91.1%) older participants developed ≥12 mIU/mL anti-HBs (P = 0.06), with geometric mean antibody concentration of 590 (95% confidence interval: 473-737) and 319 mIU/mL (95% confidence interval: 229-445; P = 0.004), respectively. Immune memory loss may have occurred in 3 younger (2.2%) and 12 older children (5.6%; P = 0.06) who were nonresponsive to first but not second vaccine challenge. CONCLUSIONS: After HBV vaccination at 2, 4 and 6 months of age, most adolescents had little or no residual antibody but nearly all responded to HBV challenge, confirming immune memory persistence. However, anamnestic responses were weaker in 15- to 16-year olds and lost in some. Booster responses in 10- to 11-year olds were vigorous in comparison. Extended evaluation of protection is warranted.

Immunogenicity and safety of 3-dose primary vaccination with combined DTPa-HBV-IPV/Hib vaccine in Canadian Aboriginal and non-Aboriginal infants.

This study compared immune responses of healthy Aboriginal and non-Aboriginal infants to Haemophilus influenzae type b (Hib) and hepatitis B virus (HBV) components of a DTaP-HBV-IPV/Hib combination vaccine, 1 month after completing dosing at 2, 4 and 6 months of age. Of 112 infants enrolled in each group, 94 Aboriginal and 107 non-Aboriginal infants qualified for the immunogenicity analysis. Anti-PRP concentrations exceeded the protective minimum (≥0.15 µg/ml) in ≥97% of infants in both groups but geometric mean concentrations (GMCs) were higher in Aboriginal infants (6.12 µg/ml versus 3.51 µg/ml). All subjects were seroprotected (anti-HBs ≥10 mIU/mL) against HBV, with groups having similar GMCs (1797.9 versus 1544.4 mIU/mL, Aboriginal versus non-Aboriginal, respectively). No safety concerns were identified. We conclude that 3-dose primary vaccination with DTaP-HBV-IPV/Hib combination vaccine elicited immune responses to Hib and HBV components that were at least as high in Aboriginal as in non-Aboriginal Canadian infants. Clinical Trial Registration NCT00753649.

Age of recipient and number of doses differentially impact human B and T cell immune memory responses to HPV vaccination.

Vaccination is one of the most effective medical interventions. However, optimization of existing as well as design of new vaccines is still mostly conducted empirically; a rational approach to vaccine design is largely prohibited by the lack of insight into the relevant mechanisms underlying immune-mediated protection. To delineate the impact of variables on immune memory formation following vaccination, we took advantage of a trial assessing the role of the age of the recipient and the number of administered doses of the quadrivalent HPV vaccine in a well-characterized longitudinal cohort of girls and young women. We found that age of the recipient and the number of doses administered differentially impact the development of B and T cell memory. Specifically, age of the recipient significantly impacted generation of HPV 18-specific B cell memory, while the number of vaccine doses displayed a significant effect on the development of HPV-specific T cell memory. Our data indicate that rational design of vaccines has to be tailored according to the desired induction of B and/or T cell memory.