Randomized Trial of 2 Schedules of Meningococcal B Vaccine in Adolescents and Young Adults, Canada1.

Emergency vaccination programs often are needed to control outbreaks of meningococcal disease caused by Neisseria meningitidis serogroup B (MenB) on college campuses. Such campaigns expend multiple campus and public health resources. We conducted a randomized, controlled, multicenter, observer-blinded trial comparing immunogenicity and tolerability of an accelerated vaccine schedule of 0 and 21 days to a longer interval of 0 and 60 days for 4-component MenB vaccine (MenB-4C) in students 17-25 years of age. At day 21 after the first MenB-4C dose, we observed protective human serum bactericidal titers >4 to MenB strains 5/99, H44/76, and NZ 98/254 in 98%-100% of participants. Geometric mean titers increased >22-fold over baseline. At day 180, >95% of participants sustained protective titers regardless of their vaccine schedule. The most common adverse event was injection site pain. An accelerated MenB-4C immunization schedule could be considered for rapid control of campus outbreaks.

Immunogenicity of 2 and 3 Doses of the Quadrivalent Human Papillomavirus Vaccine up to 120 Months Postvaccination: Follow-up of a Randomized Clinical Trial.

BACKGROUND: Several countries have implemented a 2-dose (2D) human papillomavirus (HPV) vaccination schedule for adolescents based on immunobridging studies. We compared immunogenicity of 2D vs 3-dose (3D) schedules of the quadrivalent vaccine (4vHPV) up to 10 years after the first dose. METHODS: Girls aged 9-13 years were randomized to receive 2D or 3D and were compared with women aged 16-26 receiving 3D at day 1 and months 7, 24, and 120 after the first dose. Antibody levels for HPV6/11/16/18 were evaluated using the competitive Luminex immunoassay (cLIA) and total immunoglobulin G assay. Geometric mean titers (GMTs) and seropositivity rates were compared between the different groups at different time points. Noninferiority of GMT ratios was defined as the lower bound of the 2-sided 95% confidence interval (CI) being greater than 0.5. Kinetics of antibody titers over time among study groups were examined. RESULTS: At 120 months, data from 35 2D girls, 38 3D girls, and 30 3D women were used for analyses. cLIA seropositivity rates were above 95% for all HPV vaccine types and all schedules, except HPV18, with the lowest seropositivity observed among 3D women (60.0%; 95% CI, 40.6%-77.3%). GMT ratios (cLIA) for both 2D and 3D girls were noninferior to 3 doses in women for HPV6/11/16/18. Trends were comparable between assays. CONCLUSIONS: GMTs for HPV6/11/16/18 after 2D or 3D of 4vHPV in girls were noninferior to 3D in adult women up to 120 months postvaccination. This study demonstrates long-term immunogenicity of the 2D HPV vaccine schedule.

Will Infant Hepatitis B Immunization Protect Adults?

Globally, infant hepatitis B virus (HBV) immunization programs are markedly reducing the rate of chronic HBV infections among children <5 years of age. Desirable improvements include increased birth dose coverage and better prevention of perinatal HBV transmission. Follow-up studies show that by the teenage years most of those immunized as infants have lost circulating anti-HBs antibody and some fail to respond to challenge HBV vaccination, implying loss of protection from infection. With high exposure to HBV, such individuals can develop breakthrough HBV infection but this rarely leads to chronic infection, the main goal of prevention programs. While longer-term follow-up studies into adulthood are needed, current evidence does not support a need for booster immunization of otherwise healthy teens or young adults.

Fever prophylaxis can reduce vaccine responses: A caution.

Prophylactic administration of antipyretic/analgesic drugs, started at the time of immunization and repeated 6 and 12 hours later, is sometimes undertaken to reduce postimmunization fever and irritability in infants. Two recent studies showed that such prophylaxis can reduce immune responses to some infant vaccines, warranting judicious use. In contrast, implementing treatment 6 hours or more after immunization had no effect on vaccine responses and would reduce drug exposure of asymptomatic infants.

Adverse events following live-attenuated intranasal influenza vaccination of children with cystic fibrosis: Results from two influenza seasons.

BACKGROUND: Despite the approved use of live-attenuated intranasal influenza vaccine (LAIV) for seasonal immunization of patients with cystic fibrosis (CF), many questions remain unanswered regarding the timing, duration, and types of adverse events that occur following administration of this vaccine. METHODS: In 2012 and 2013, 264 LAIV doses were administered to 198 patients aged 2-19 with CF. Vaccinees were followed prospectively for 55 days after vaccination (day 0) and information on adverse events was collected. Bayesian change-point analysis was used to identify the risk period following LAIV during which participants had a higher risk of reporting adverse events. Multivariable zero-inflated Poisson regression models were then used to estimate the adjusted incidence rate ratio (aIRR) and 95% credible interval (CrI) of reporting each adverse event in the risk period versus the control period. RESULTS: There was a higher risk of reporting serious adverse events (SAEs) (aIRR 1.45, 95% CrI (0.29, 5.17)) and solicited symptoms during days 0-6 of follow-up compared to control period days 7-55. However, most SAEs were not causally related to LAIV and the solicited symptom episodes were brief, usually lasting 1-2 days. There was no increased risk of antibiotic prescriptions for respiratory conditions in the risk vs. control periods (aIRR 0.48, 95% CrI (0.23, 0.91)). CONCLUSIONS: Adverse events were most common 0-6 days after LAIV administration but were generally benign and self-limiting. Pulmonary exacerbations did not increase in frequency.

Cellular immune responses of older adults to four influenza vaccines: Results of a randomized, controlled comparison.

Cellular immunity is important for protection against the serious complications of influenza in older adults. As it is unclear if newer influenza vaccines elicit greater cellular responses than standard vaccines, we compared responses to 2 standard and 2 newer licensed trivalent inactivated vaccines (TIVs) in a randomized trial in older adults. Non-frail adults ≥ 65 y old were randomly assigned to receive standard subunit, MF59-adjuvanted subunit, standard split-virus or intradermal split-virus TIV. Peripheral blood mononuclear cells (PBMC) harvested pre- and 3-weeks post-vaccination were stimulated with live A/H3N2 virus. PBMC supernatants were tested for interleukin 10 (IL-10) and interferon gamma (IFN-γ), and lysates for granzyme B (GrB). Flow cytometry identified CD4+ and CD8+ T- cells expressing intracellular IL-2, IL-10, IFN-γ, GrB, or perforin. Differences following immunization were assessed for paired subject samples and among vaccines. 120 seniors participated, 29-31 per group, which were well matched demographically. Virus-stimulated PBMCs were GrB-rich before and after vaccination, with minimal increases evident. Immunization did not increase secretion of IFN-γ or IL-10. However, cytolytic effector T-cells (CD8+GrB+perforin+) increased significantly in percentage post-vaccination in all groups, to similar mean values across groups. CD4+GrB+perforin+ T-cells also increased significantly after each vaccine, to similar mean values among vaccines. Vaccination did not increase the low baseline percentages of CD4+ or CD8+ T-cells expressing IFN-γ, IL-2 or IL-10 . In conclusion, participants had pre-existing cellular immunity to H3N2 virus. All 4 vaccines boosted cellular responses to a similar but limited extent, particularly cytolytic effector CD8+ T-cells associated with clinical protection against influenza.

Pertussis and influenza immunisation during pregnancy: a landscape review.

Immunisation during pregnancy is a relatively new strategy, and is currently limited to tetanus, pertussis, and influenza vaccines. None of these vaccines were developed specifically for use in pregnancy, but they provide an effective method of protecting mothers and young infants. In response to increases in pertussis morbidity and mortality among young infants, several countries have recommended universal tetanus, diphtheria, and acellular pertussis immunisation during pregnancy. Similarly, many countries recommend influenza immunisation during pregnancy to reduce the risk of disease for mother and infant. Although scientific evidence to support maternal immunisation against pertussis and influenza is rapidly accumulating, important knowledge gaps remain that need to be addressed by future research, which we have highlighted in this Series paper.

Maternal immunisation: collaborating with mother nature.

Maternal immunisation has the potential to substantially reduce morbidity and mortality from infectious diseases after birth. The success of tetanus, influenza, and pertussis immunisation during pregnancy has led to consideration of additional maternal immunisation strategies to prevent group B streptococcus and respiratory syncytial virus infections, among others. However, many gaps in knowledge regarding the immunobiology of maternal immunisation prevent the optimal design and application of this successful public health intervention. Therefore, we did an innovative landscape analysis to identify research priorities. Key topics were delineated through review of the published literature, consultation with vaccine developers and regulatory agencies, and a collaborative workshop that gathered experts across several maternal immunisation initiatives-group B streptococcus, respiratory syncytial virus, pertussis, and influenza. Finally, a global online survey prioritised the identified knowledge gaps on the basis of expert opinion about their importance and relevance. Here we present the results of this worldwide landscape analysis and discuss the identified research gaps.

Viral interference and the live-attenuated intranasal influenza vaccine: Results from a pediatric cohort with cystic fibrosis.

BACKGROUND: The objective of this study was to explore the effects of viral co-detection in individuals recently vaccinated with the live-attenuated intranasal influenza virus vaccine (LAIV) on the detection of influenza RNA. METHODS: Before the 2013-2014 influenza season, nasal swabs were obtained from 59 pediatric participants with cystic fibrosis (CF) and 17 of their healthy siblings immediately before vaccination and 4 times during the week of follow-up. Real-time RT-PCR assays were used to detect influenza RNA. Co-detection of a non-influenza respiratory virus (NIRV) at the time of vaccination was determined by a multiplex RT-PCR assay. Differences in the proportions and rates of influenza detection and their 95% credible intervals (CrI) were estimated. RESULTS: Influenza RNA was detected in 16% fewer participants (95% CrI: -7, 39%) throughout follow-up in the NIRV-positive group compared with the NIRV-negative group (59% vs. 75%). This was also observed in participants with CF alone (66% vs. 74%; RD = 8% 95% CrI: -16, 33%) as well as in healthy participants only (75% vs. 30%; RD = 45%, 95% CrI: -2, 81%). Influenza was detected in NIRV-negative subjects for 0.49 d more compared with NIRV-positive subjects (95% CrI: -0.37, 1.26). CONCLUSION: The observed proportion of subjects in whom influenza RNA was detected and the duration of detection differed slightly between NIRV- positive and -negative subjects. However, wide credible intervals for the difference preclude definitive conclusions. If true, this observed association may be related to a recent viral respiratory infection, a phenomenon known as viral interference.

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.

Do Dose Numbers Matter?: Evaluation of Differing Infant and Toddler Meningococcal C Conjugate Vaccine Programs in Canadian Children.

BACKGROUND: The diversity of Canadian infant meningococcal C conjugate (MenC) vaccine programs is unique among countries providing MenC vaccines and offers a valuable opportunity to determine the optimal vaccine program. This longitudinal study assessed differences in seroprotection by 3 different vaccine schedules in children two years after receiving either 1 toddler MenC vaccine dose (1 dose), 1 infant and 1 toddler dose (2 doses), or 2 infant and 1 toddler MenC vaccine dose (3 doses). METHODS: Three similar cohorts of healthy infants from 1, 2 and 3 dose program areas were enrolled before to their 12 month toddler dose and vaccinated with MenC-tetanus toxoid (MenC-TT) conjugate vaccine. Sera obtained 2 years later were assayed for serogroup C bactericidal activity using standardized procedures with rabbit as the exogenous complement source. Serum bactericidal activity titers ≥1:8 were considered protective. RESULTS: Results were available for 384 children. Rates of seroprotection at 36 months of age were significantly different between the 1 and 3 dose programs, but confidence intervals overlapped between the 1 and 2 dose programs and between the 2 and 3 dose programs: 1 dose 92% (95% confidence interval: 86%-96%) versus 99% (95%-100%) with 2 doses and 100% (97%-100%) with 3 doses. Geometric mean titers were significantly different at 12.1 (10.8-13.5), 32.4 (28.9-36.2) and 50.6 (45.7-55.9) in the 1, 2 and 3 dose programs, respectively. CONCLUSIONS: At 36 months of age, evidence of seroprotection remained for greater than 90% of participants. Our results indicate that 1 toddler dose or 1 infant plus 1 toddler dose with MenC-TT vaccine provides seroprotection against MenC disease in early childhood.

Influenza Virus Detection Following Administration of Live-Attenuated Intranasal Influenza Vaccine in Children With Cystic Fibrosis and Their Healthy Siblings.

Background. We aimed to explore the detection profile of influenza viruses following live-attenuated intranasal influenza vaccination (LAIV) in children aged 2-19 years with and without cystic fibrosis (CF). Methods. Before the 2013-2014 influenza season, flocked nasal swabs were obtained before vaccination and 4 times in the week of follow-up from 76 participants (nCF: 57; nhealthy: 19). Influenza was detected by reverse transcription polymerase chain reaction (RT-PCR) assays. A Bayesian hierarchical logistic regression model was used to estimate the effect of CF status and age on influenza detection. Results. Overall, 69% of the study cohort shed influenza RNA during follow-up. The mean duration of RT-PCR detection was 2.09 days (95% credible interval [CrI]: 1.73-2.48). The odds of influenza RNA detection on day 1 following vaccination decreased with age in years (odds ratio [OR]: 0.82 per year; 95% CrI: 0.70-0.95), and subjects with CF had higher odds of influenza RNA detection on day 1 of follow-up (OR: 5.09; 95% CrI: 1.02-29.9). Conclusion. Despite the small sample size, our results indicate that LAIV vaccine strains are detectable during the week after LAIV, mainly in younger individuals and vaccinees with CF. It remains unclear whether recommendations for avoiding contact with severely immunocompromised patients should differ for these groups.

Hospitalization for Influenza A Versus B.

BACKGROUND: The extent to which influenza A and B infection differs remains uncertain. METHODS: Using active surveillance data from the Canadian Immunization Monitoring Program Active at 12 pediatric hospitals, we compared clinical characteristics and outcomes of children ≤16 years admitted with laboratory-confirmed influenza B or seasonal influenza A. We also examined factors associated with ICU admission in children hospitalized with influenza B. RESULTS: Over 8 nonpandemic influenza seasons (2004-2013), we identified 1510 influenza B and 2645 influenza A cases; median ages were 3.9 and 2.0 years, respectively (P < .0001). Compared with influenza A patients, influenza B patients were more likely to have a vaccine-indicated condition (odds ratio [OR] = 1.30; 95% confidence interval [CI] = 1.14-1.47). Symptoms more often associated with influenza B were headache, abdominal pain, and myalgia (P < .0001 for all symptoms after adjustment for age and health status). The proportion of deaths attributable to influenza was significantly greater for influenza B (1.1%) than influenza A (0.4%); adjusted for age and health status, OR was 2.65 (95% CI = 1.18-5.94). A similar adjusted OR was obtained for all-cause mortality (OR = 2.95; 95% CI = 1.34-6.49). Among healthy children with influenza B, age ≥10 years (relative to <6 months) was associated with the greatest odds of ICU admission (OR = 5.79; 95% CI = 1.91-17.57). CONCLUSIONS: Mortality associated with pediatric influenza B infection was greater than that of influenza A. Among healthy children hosptialized with influenza B, those 10 years and older had a significant risk of ICU admission.

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.

Outcomes of invasive meningococcal disease in adults and children in Canada between 2002 and 2011: a prospective cohort study.

BACKGROUND: Neisseria meningitidis causes 500 000 cases of septicemia and meningitis worldwide annually, with approximately 200 cases in Canada each year. Previous studies describe a case-fatality rate of 5%-15% and up to 20% of survivors suffering from long-term disability. METHODS: This study was performed in Canada between 2002 and 2011; the study area included >50% of the country's population. We identified risk factors associated with death and the development of complications in children and adults admitted to hospital with confirmed invasive meningococcal disease (IMD). Clinical information was obtained from hospital records. Risk factors for death and complications were analyzed by univariate and multivariable analyses. RESULTS: Of 868 individuals hospitalized with IMD, there were 73 deaths (8.4%) and 157 (18%) developed complications. The most common complications were hearing loss (5.4%), skin scarring (5.4%), amputation (3.4%), renal dysfunction (2.6%), and seizures (2.5%). Mortality was independently associated with shock (adjusted odds ratio [aOR], 23.30; P<.0001), age (aOR, 1.02 per 1-year increased age; P<.0001), symptom onset within 24 hours of admission (aOR, 1.80; P=.0471), and admission to the intensive care unit (aOR, 0.41; P=.0196). Development of complications was independently associated with seizures (aOR, 4.55; P<.0001), shock (aOR, 3.10; P<.0001), abnormal platelet count (aOR, 2.14; P=.0002), bruising (aOR, 3.17; P=.0059), abnormal white blood cell count (aOR, 0.52; P=.0100), and prior antibiotic exposure (aOR, 0.27; P=.0273). CONCLUSIONS: Outcomes following IMD remain poor in this resource-rich setting in the 21st century. These data identify priorities for clinical management of adults and children with IMD, and provide prognostic information for affected patients and their families and cost-effectiveness analyses for meningococcal vaccine programs.

The impact of the meningococcal serogroup C conjugate vaccine in Canada between 2002 and 2012.

BACKGROUND: Before 2001, the incidence of invasive meningococcal disease (IMD) in Canada was 1.0 per 100 000 per year, with 40% of cases caused by serogroup C organisms. During 2001-2005 all provinces introduced the meningococcal serogroup C conjugate vaccine (MCCV) into their routine infant immunization schedule. METHODS: Active, prospective, population-based surveillance of IMD in children and adults was conducted by the Canadian Immunization Monitoring Program, ACTive (IMPACT) during 2002-2012. Inclusion criteria were admission to hospital and identification of Neisseria meningitidis from a sterile site. Incidence was estimated using population census data from Statistics Canada. RESULTS: Prior to MCCV introduction, serogroup C disease incidence was 0.07-0.25 per 100 000 per year depending on the province. Following vaccine introduction, serogroup C disease decreased to <0.05 per 100 000 per year, with a reduction of 14% per year (P = .0014). A decrease occurred in all provinces, despite differing schedules being implemented. The largest decrease of 83% (from 0.27 to 0.05 per 100 000 per year) occurred in the 15-24 year age group (P = .0100) who were not vaccinated in all provinces. There was no impact on the incidence of nonserogroup C disease over the same period (P = .9811). CONCLUSIONS: MCCV dramatically reduced the incidence of serogroup C IMD in Canada through both direct and indirect effects. The observation that disease incidence decreased with different schedules suggests that the doses at 12 months (common to all provinces) and adolescence (7 of 8 provinces studied) were critical in achieving disease control.

A randomized study to evaluate the immunogenicity and safety of a heptavalent diphtheria, tetanus, pertussis, hepatitis B, poliomyelitis, haemophilus influenzae b, and meningococcal serogroup C combination vaccine administered to infants at 2, 4 and 12 months of age.

BACKGROUND: The immunogenicity and safety of the investigational diphtheria, tetanus, acellular pertussis, hepatitis B, poliomyelitis, Haemophilus influenzae type b (Hib) and meningococcal serogroup C (MenC) heptavalent combination vaccine were compared with those of licensed control vaccines. METHODS: In this open, phase II, randomized study (NCT01090453), 480 infants from Germany, France and Canada received the heptavalent vaccine (Hepta group) or hexavalent and monovalent MenC control vaccines (HexaMenC group) co-administered with a 13-valent pneumococcal conjugate vaccine at 2, 4 and 12 months of age. Immunogenicity was measured 1 month after the second primary dose, and before and 1 month after the booster dose. Safety and reactogenicity were also evaluated. RESULTS: Non-inferiority of immune responses to MenC and Hib induced by 2-dose primary vaccination with the heptavalent vaccine versus control vaccines was demonstrated. In exploratory analyses, postprimary and postbooster functional antibody geometric mean titers against MenC tended to be lower (1119.5 vs. 3200.5; 2653.8 vs. 6028.4) and antibody geometric mean concentrations against Hib higher (1.594 vs. 0.671 µg/mL; 17.678 vs. 13.737 µg/mL) in the Hepta versus the HexaMenC group. The heptavalent and control vaccines were immunogenic to all other antigens, although immune responses to poliovirus were lower than expected in both groups. No differences in safety and reactogenicity profiles were detected between groups. CONCLUSIONS: The heptavalent vaccine induced non-inferior MenC and Hib responses compared with control vaccines. Both vaccination regimens, when administered at 2, 4 and 12 months of age, had comparable safety profiles and were immunogenic to all antigens, with lower-than-expected responses to poliomyelitis.

Burden of seasonal influenza in children with neurodevelopmental conditions.

BACKGROUND: Studies have identified certain neurologic and neurodevelopmental conditions (NNC) as risk factors for severe influenza infection. The Canadian National Advisory Committee on Immunization does not currently recognize children with NNC as having a high risk of complicated influenza infection unless their condition compromises handling of respiratory secretions. We describe the burden of influenza in hospitalized children with NNC, focusing on those without potential airway compromise. METHODS: Using multi-year surveillance data obtained by the Canadian Immunization Monitoring Program, Active (IMPACT), we examined presenting signs and symptoms, risk factors and outcomes of children hospitalized with seasonal influenza at 12 Canadian pediatric referral centers. Comparisons were made between children with various NNC and other medical conditions, with and without influenza vaccine indications. The analysis is descriptive with selected comparisons made among groups for important indicators of disease severity. RESULTS: We identified 1991 children hospitalized with influenza over 5 seasons: 293 had NNC, 115 of whom did not have airway compromise or another vaccine indication. The latter group presented with seizures more frequently than those with NNC and a vaccine indication (41.7% vs. 26.4%; P = 0.006) and required intensive care unit admission (20.9% vs. 11.8%; P = 0.02) and mechanical ventilation (14.8% vs. 4.5%; P < 0.001) more often than children without NNC but with a vaccine indication. CONCLUSIONS: The burden of influenza infection in children with NNC, even those whose conditions do not obviously compromise respiratory function, is significant. All children with NNC should be recognized as having a high risk of complicated influenza infection and be targeted to receive influenza immunization.

Knowledge, attitudes, beliefs and behaviours of older adults about pneumococcal immunization, a Public Health Agency of Canada/Canadian Institutes of Health Research Influenza Research Network (PCIRN) investigation.

BACKGROUND: Fewer Canadian seniors are vaccinated against pneumococcal disease than receive the influenza vaccine annually. Improved understanding of factors influencing pneumococcal vaccination among older adults is needed to improve vaccine uptake. METHODS: A self-administered survey measuring knowledge, attitudes, beliefs and behaviours about pneumococcal vaccination was administered to a cohort of seniors participating in a clinical trial of seasonal influenza vaccines at eight centers across Canada. Eligible participants were ambulatory adults 65 years of age or older, in good health or with stable health conditions, previously given influenza vaccine. The primary outcome was self-reported receipt of pneumococcal vaccination. Multi-variable logistic regression was used to determine factors significantly associated with pneumococcal vaccine receipt. RESULTS: A total of 863 participants completed questionnaires (response rate 92%); 58% indicated they had received the pneumococcal vaccine. Being offered the vaccine by a health care provider had the strongest relationship with vaccine receipt (AOR 23.4 (95% CI 13.4-40.7)). Other variables that remained significantly associated with vaccine receipt in the multivariable model included having heard of the vaccine (AOR 10.1(95% CI 4.7-21.7)), and strongly agreeing that it is important for adults > 65 to be vaccinated against pneumococcus (AOR 3.3 (95% CI 1.2-9.2)). Participants who were < 70 years of age were less likely to be vaccinated. CONCLUSIONS: These results indicate healthcare recommendation significantly influenced vaccine uptake in this population of older adults. Measures to encourage healthcare providers to offer the vaccine may help increase coverage.