Influenza vaccine effectiveness: Maintained protection throughout the duration of influenza seasons 2010–2011 through 2013–2014

BackgroundFactors, such as age, comorbidities, vaccine type, herd immunity, previous influenza exposure, and antigenic shift may impact the immune response to the influenza vaccine, protection against circulating strains, and antibody waning. Evaluating vaccine effectiveness (VE) is important for informing timing of vaccine administration and evaluating overall vaccine benefit.MethodsVE was assessed using febrile respiratory illness surveillance among Department of Defense non-active duty beneficiaries from influenza seasons 2010–2011 through 2013–2014. Respiratory specimens were taken from participants meeting the case definition and tested by polymerase chain reaction for influenza. VE was calculated using logistic regression and by taking 1 minus the odds ratio of being vaccinated in the laboratory confirmed positive influenza cases versus laboratory confirmed negative controls.ResultsThis study included 1486 participants. We found an overall adjusted VE that provided significant and fairly consistent protection ranging from 54% to 67% during 0–180 days postvaccination. This VE dropped to −11% (95% confidence interval: −102% to 39%) during 181–365 days.ConclusionsOur study found moderate VE up to 6 months postvaccination. Since the influenza season starts at different times each year, optimal timing is difficult to predict. Consequently, early influenza vaccination may still offer the best overall protection.     

Understanding influenza vaccine protection in the community: An assessment of the 2013 influenza season in Victoria,Australia

BackgroundThe influenza virus undergoes frequent antigenic drift, necessitating annual review of the composition of the influenza vaccine. Vaccination is an important strategy for reducing the impact and burden of influenza, and estimating vaccine effectiveness (VE) each year informs surveillance and preventative measures. We aimed to describe the influenza season and to estimate the effectiveness of the influenza vaccine in Victoria, Australia, in 2013.MethodsRoutine laboratory notifications, general practitioner sentinel surveillance (including a medical deputising service) data, and sentinel hospital admission surveillance data for the influenza season (29 April to 27 October 2013) were collated in Victoria, Australia, to describe influenza-like illness or confirmed influenza during the season. General practitioner sentinel surveillance data were used to estimate VE against medically-attended laboratory confirmed influenza. VE was estimated using the case test negative design as 1 − adjusted odds ratio (odds of vaccination in cases compared with controls) × 100%. Cases tested positive for influenza while non-cases (controls) tested negative. Estimates were adjusted for age group, week of onset, time to swabbing and co-morbidities.ResultsThe 2013 influenza season was characterised by relatively low activity with a late peak. Influenza B circulation preceded that of influenza A(H1)pdm09, with very little influenza A(H3) circulation. Adjusted VE for all influenza was 55% (95%CI: −11, 82), for influenza A(H1)pdm09 was 43% (95%CI: −132, 86), and for influenza B was 56% (95%CI: −51, 87) Imputation of missing data raised the influenza VE point estimate to 64% (95%CI: 13, 85).ConclusionsClinicians can continue to promote a positive approach to influenza vaccination, understanding that inactivated influenza vaccines prevent at least 50% of laboratory-confirmed outcomes in hospitals and the community.     

Workplace availability,risk group and perceived barriers predictive of 2016–17 influenza vaccine uptake in the United States: A cross-sectional study

BackgroundSeasonal influenza, though mostly self-limited in the healthy adult, may lead to severe disease and/or complications in subpopulations. Annual influenza vaccination is available in many countries with coverage goals rarely being met. We conducted a cross-sectional study of influenza vaccine uptake and explored socio-demographic, economic, and psychological factors that explained vaccine uptake.MethodsThe survey was administered via Amazon Mechanical Turk (MTurk) to United States residents in January 2017, using the Qualtrics platform. Using principal axis factor analysis, we reduced the 25 items theory-based psychological determinants into the primary constructs they measure if/when internal consistency was sufficient (Cronbach’s alpha >0.60). Logistic regression models were used to quantify the association of socio-demographic, economic, and psychological factors with reported vaccine behavior in the 2016–17 flu season.Results1007 participants completed the survey, sex distribution was even, 67% had 25–44 years of age, and 61% annual household income of $30–99 thousand United States dollars. About 25% had the flu shot offered at their workplace and 20% reported belonging to a group for whom the flu shot is recommended. Vaccine uptake was 31.5%. Eight predictors remained in the final adjusted model (R² = 0.489), having the vaccine offered at the workplace, belonging to a group for whom the vaccine is recommended, and higher perceived barriers were the strongest predictors of vaccine uptake, increasing (and decreasing in the case of barriers) the odds by >3-fold. Additionally, higher household income, higher perceived susceptibility and higher perceived benefits also independently predicted vaccine uptake.DiscussionWe found evidence that perceived barriers significantly impaired vaccine uptake to the same extent that having the vaccine offered at the workplace or belonging to a group for whom the vaccine is recommended facilitated uptake. Ideally, a better understanding of drivers of vaccine hesitancy will result in improved interventions to increase vaccine uptake.     

Evaluación de una intervención comunitaria para incrementar la cobertura vacunal de la gripe en mujeres embarazadas

ObjectiveTo know the impact of the educational intervention carried out on the professionals of a basic health area and their community participation group, which make up the intervention group (IG), and to analyze its repercussion on the vaccination coverage achieved for influenza in the risk group (pregnant and puerperal women) comparing it with its neighboring basic zone, which makes up the control group (CG), during the 2019/20 vaccination season.DesignQuasi-experimental study of community intervention.SiteTwo basic health zones belonging to the Elche-Crevillente health department, Spain.ParticipantsPregnant and postpartum women from 2 basic health areas and the community participation group. Health professionals directly related to the flu vaccination campaign.InterventionsTraining session for the IG prior to the 2019/20 flu campaign.Main measurementsAttitudes towards influenza vaccination in health professionals through the validated CAPSVA questionnaire and the vaccination coverage of pregnant and postpartum women through the Nominal Vaccine Registry and their acceptance of the vaccine in the midwife's office.ResultsThe influenza vaccination coverage data recorded in Nominal Vaccine Registry for pregnant and puerperal women was 26.4% (n = 207) in the IG and 19.7% (n = 144) in the CG (p = 0.001), with an incidence ratio of 1.34, thus achieving 34% more vaccination in the IG. Acceptance for vaccination in the midwife's office was also high, with 96.5% immunization in IG vs. 89.0% in CG, with a RR = 1.09 (95% CI 1.01-1.62).ConclusionsJoint training strategies for professionals and community assets improve the results of vaccination coverage.     

Birth outcomes for Australian mother-infant pairs who received an influenza vaccine during pregnancy, 2012–2014: The FluMum study

IntroductionIn Australia, influenza vaccination is recommended for all women who will be pregnant during the influenza season. Vaccine safety and effectiveness are key concerns and influencers of uptake for both vaccine providers and families. We assessed the safety of receiving an influenza vaccination during any trimester of pregnancy with respect to preterm births and infant birthweight.MethodsWe conducted a nested retrospective cohort study of ‘FluMum’ participants (2012–2014). Our primary exposure of interest was influenza vaccination during pregnancy. The primary outcomes of interest were infant birthweight and weeks’ gestation at birth for live singleton infants. Analyses included comparisons of these birth outcomes by vaccination status and trimester of pregnancy an influenza vaccine was given. We calculated means, proportions, and relative risks and performed multivariable logistic regression for potential confounding factors.ResultsIn the 7126 mother-infant pairs enrolled in this study, mean maternal age at infant birth was 31.7 years. Influenza vaccine uptake in pregnancy was 34%. Most mothers with a known date of vaccination received a vaccine in the second trimester (51%). Those mothers with a co-morbidity or risk factor were 13% more likely to have influenza vaccine during pregnancy compared to other mothers (RR 1.13, 95% CI 1.04–1.24, p = 0.007). Mean weeks’ gestation at birth was 38.7 for the vaccinated and 38.8 for the unvaccinated group (p = 0.051). Infants in the vaccinated group weighed 15 g less in birthweight compared to the unvaccinated infants (95% CI −12.8 to 42.2, p = 0.29).ConclusionResults arising from this large Australian cohort study are reassuring with respect to two critical safety outcomes; preterm births and low infant birthweights. Studies examining a broader range of birth outcomes following influenza vaccination during pregnancy are required, particularly now that maternal vaccination in pregnancy has expanded to include pertussis as well as influenza.     

Parental perceptions of childhood seasonal influenza vaccination in Singapore: A cross-sectional survey

PurposeSeasonal influenza vaccination is recommended in children aged 6–59 months, but little is known about child vaccination coverage and determinants in Asian settings. We report the results of a survey of knowledge, attitudes, practices, and determinants of child influenza vaccination in Singapore.MethodsIn December 2015-March 2016, we conducted a survey of 332 parents of children aged 6 months to 5 years attending pre-schools. We assessed child influenza vaccine coverage and parental knowledge, attitudes, and practices of child influenza vaccination. We used multivariable regression and structural equation models to identify factors associated with child influenza vaccination.ResultsKnowledge about influenza, perceived benefit of vaccination, and willingness to vaccinate were high. However, only 32% of children had ever received influenza vaccine, and only 15% in the past year. Factors independently associated with child influenza vaccination included: being recommended influenza vaccine by a child’s doctor (prevalence ratio (PR) = 2.47, 95% CI: 1.75–3.48); receiving influenza vaccine information from a private general practitioner (PR = 1.47, 95% CI: 1.05–2.04); regularly receiving pre-travel influenza vaccine (PR = 1.64, 95% CI: 1.19–2.25); higher willingness to vaccinate (PR = 1.58, 95% CI:1.24–2.04 per unit increase in willingness score); and feeling well-informed about influenza vaccine (PR = 1.44, 95% CI: 1.04–1.99). Parents who obtained influenza vaccine information from television were less likely to have vaccinated their child (PR = 0.44, 95% CI: 0.23–0.85). Path analysis indicated that being recommended vaccination by a child's doctor increased willingness to vaccinate and self-efficacy (feeling well-informed about influenza vaccine). Median willingness-to-pay for a dose of influenza vaccine was SGD30 (interquartile range: SGD20-SGD50), and was higher in parents of vaccinated compared with unvaccinated children (SGD45 vs SGD30, p = 0.0012).ConclusionKnowledge and willingness to vaccinate was high in this parent population, but influenza vaccine uptake in children was low. Encouraging medical professionals to recommend vaccination of eligible children is key to improving uptake.     

Efficacy and safety of high-dose influenza vaccine in elderly adults: A systematic review and meta-analysis

IntroductionOlder adults are prioritized for influenza vaccination but also have lowered antibody responses to the vaccine. Higher-doses of influenza antigen may increase immune response and thus be more effective. Our objectives were to compare the efficacy and safety of the high-dose influenza vaccine to the standard-dose influenza vaccine in the elderly (age > 65).MethodsData sources: Randomized trials (RCTs) from Medline (Ovid), EMBASE (Ovid), Cochrane Library (Wiley), ClinicalTrials.gov, reference lists of relevant articles, and gray literature.Study selection: Two reviewers independently identified RCTs comparing high-dose influenza vaccine (60 μg of hemagglutinin per strain) to standard-dose influenza vaccine (15 μg of hemagglutinin per strain) in adults over the age of 65 years.Data extraction: Two reviewers independently extracted trial-level data including population characteristics, interventions, outcomes, and funding sources. Risk of bias was assessed using the Cochrane Risk of Bias tool.ResultsWe included seven eligible trials; all were categorized as having a low (n = 3) or unclear (n = 4) risk of bias. Patients receiving the high-dose vaccine had significantly less risk of developing laboratory-confirmed influenza infections (Relative Risk 0.76, 95%CI 0.65 to 0.90; I² 0%, 2 trials, 41,141 patients). Post-vaccination geometric mean titres and seroprotection rates were also higher in high-dose vaccine recipients. There were no protocol-defined serious adverse events in the included trials in either group.ConclusionsIn elderly adults, the high-dose influenza vaccine was well-tolerated, more immunogenic, and more efficacious in preventing influenza infections than the standard-dose vaccine. Further pragmatic trials are needed to determine if the higher efficacy translates into higher vaccine effectiveness in adults over the age of 65.     

Factors associated with influenza vaccination in middle and older aged Australian adults according to eligibility for the national vaccination program

BackgroundIn Australia, influenza vaccination is recommended and provided free of charge for all adults aged ≥65 years and those aged <65 years with specific risk factors. Other than age, there is limited information on characteristics associated with vaccine uptake.MethodsWe used the 45 and Up Study, a large cohort of adults aged ≥45 years, who completed a questionnaire in 2012 asking about influenza vaccination. We compared characteristics of those reporting influenza vaccination in those aged <65 and ≥65 years using a log binomial model to estimate relative rates (RRs), adjusted for age and other factors.ResultsAmong 27,036 participants, the proportion reporting influenza vaccination in the last year increased steadily with age from 24.6% in those <54 years to 67.2% in those 75–79 years; of those eligible for universal free vaccine, (≥65 years) 57.3% had an influenza vaccination in the previous year. Many characteristics associated with higher vaccination rates in adults aged <65 years (mean 60.7) and those ≥65 years (mean 73.7) were similar. These included sex (women versus men: <65 years, aRR = 1.14[95% CI 1.08–1.20]; ≥65 years, aRR = 1.04[1.02–1.07]), higher BMI (≥30 kg/m² versus >18.5 to <25 kg/m²: <65 years, aRR = 1.16[1.09–1.24]; ≥65 years, aRR = 1.06[1.03–1.09]), requiring assistance with daily tasks versus not (<65 years, aRR = 1.27[1.15–1.40]; ≥65 years, aRR = 1.05[1.02–1.09]) and reporting versus not reporting specific chronic illnesses (<65 years, aRR = 1.55 [1.48–1.63]; ≥65 years, aRR = 1.08[1.06–1.10]). Current smokers had lower vaccination rates (<65 years, aRR = 0.78[0.69–0.90]; ≥65 years, aRR = 0.91[0.84–0.99]). Among those aged <65 years only, being a carer, higher income, and education were associated with influenza vaccination (aRR = 1.32[1.19–1.47], 1.17[1.10–1.24] and 1.12[1.10–1.22] respectively). Non-English speaking country of birth was associated with lower vaccination rates in ≥65 years (aRR 0.86[0.81–0.92]).ConclusionsFactors most strongly associated with vaccination were age and among those aged <65 years, having a medical indication recommended for influenza vaccination, suggesting higher uptake among those who can access free vaccine. Among those eligible for free vaccination, interventions could be targeted towards men, smokers, those from non-English speaking backgrounds and those <65 years with a medical indication.     

Brief education to promote maternal influenza vaccine uptake: A randomized controlled trial

BackgroundAlthough pregnant women are the highest priority group for seasonal influenza vaccination, maternal influenza vaccination rates remain suboptimal. The purpose of this study was to evaluate the effect of a brief education intervention on maternal influenza vaccine uptake.MethodsDuring the 2013–14 and 2014–15 influenza seasons, we recruited 321 pregnant women from the antenatal clinics of 4 out of 8 public hospitals in Hong Kong with obstetric services. Hospitals were geographically dispersed and provided services to pregnant women with variable socioeconomic backgrounds. Participants were randomized to receive either standard antenatal care or brief one-to-one education. Participants received telephone follow-up at 2 weeks postpartum. The primary study outcome was self-reported receipt of influenza vaccination during pregnancy. The secondary outcomes were the proportion of participants who initiated discussion about influenza vaccination with a health care professional and the proportion of participants who attempted to get vaccinated.ResultsCompared with participants who received standard care, the vaccination rate was higher among participants who received brief education (21.1% vs. 10%; p = 0.006). More participants in the education group initiated discussion about influenza vaccination with their HCP (19.9% vs. 13.1%; p = 0.10), but the difference was not statistically significant. Of participants who did not receive the influenza vaccine (n = 271), 45 attempted to get vaccinated. A significantly higher proportion of participants who attempted to get vaccinated were in the intervention group (82.2% vs. 17.8%; p < 0.001). If participants who had attempted vaccination had received the vaccine, vaccination rates would have been substantially higher (44.1% vs. 15%; p < 0.001). Twenty-six participants were advised against influenza vaccination by a healthcare professional, including general practitioners, obstetricians, and nurses.ConclusionAlthough brief education was effective in improving vaccination uptake among pregnant women, overall vaccination rates remain suboptimal. Multicomponent approaches, including positive vaccination recommendations by healthcare professionals, are needed to promote maternal influenza vaccination.Clinical Trial Registration: www.clinicaltrials.gov (NCT01772901).     

Risk factors for severe outcomes among members of the United States military hospitalized with pneumonia and influenza, 2000–2012

BackgroundThe progression from hospitalization for a respiratory infection to requiring substantial supportive therapy is a key stage of the influenza severity pyramid. Respiratory infections are responsible for 300,000–400,000 medical encounters each year among US military personnel, some of which progress to severe acute respiratory infections.MethodsWe obtained data on 11,086 hospitalizations for pneumonia and influenza (P&I) among non-recruit US military service members during the period of 1 January 2000 through 31 December 2012. From these, we identified 512 P&I hospitalizations that progressed to severe episodes using standard case definitions. We evaluated the effect of demographic and occupational characteristics, co-morbid conditions, and history of influenza vaccination on the risk of a hospitalized P&I case becoming a severe case. We also evaluated the risk of a severe outcome and the length of time since influenza vaccination (within 180, 60, and 30 days).ResultsThe median age of subjects at the time of the P&I episode was 32 years (range, 28–40) and subjects were predominantly male (89.5%). In a univariate analysis, demographic risk factors for a severe episode included service in the US Air Force (RR = 1.6 relative to US Army, 95%CI 1.3–2.1), US Coast Guard (RR = 2.1, 1.2–3.7) or US Navy (RR = 1.4, 1.1–1.8). Being born in the US and recent influenza vaccination (within 180 days of episode) were protective against developing severe disease. Among co-morbid conditions, univariate risk factors for severe disease included chronic renal or liver disease (RR = 4.98, 95%CI 4.1–6.1), diseases of the circulatory system (RR = 3.1, 95%CI 2.6–3.7), diabetes mellitus (RR = 2.3, 95%CI 1.5–3.6), obesity (RR = 1.6, 95%CI 1.2–2.1), cancer (RR = 1.6, 95%CI 1.3–2.0), and chronic obstructive pulmonary disease (RR = 1.4, 95%CI 1.1–1.7). Although many of the risk factors found to be significant in univariate analysis were no longer significant under a multivariate analysis, receipt of any influenza vaccine within 180 days of episode remained protective (RR = 0.81, 95%CI 0.67–0.99), while serving in the US Coast Guard (RR = 1.9, 95%CI 1.1–3.4) or US Air Force (RR = 1. 5, 95%CI 1.2–2.0), presence of renal or liver disease (RR = 3.6, 95%CI 2.9–4.6), and diseases of the circulatory system (RR = 2.2, 95%CI 1.8–2.8), remained significantly associated with a higher risk of developing severe disease.ConclusionsIn a large cohort, after adjusting for many possible risk factors, influenza vaccination was protective against severe episodes among P&I hospitalizations. The service-specific (US Coast Guard or US Air Force) increased risk may represent some differences in data (e.g., coding or reporting practices) as opposed to genuine differences in physiological outcome. Our findings suggest that renal and liver disease as well as diseases of the circulatory system may contribute to influenza severity in this population independently of age and other potential comorbidities. These findings provide additional evidence for the prioritization of specific risk groups within the US military for influenza vaccination     

Influenza vaccines effectiveness 2013–14 through 2015–16, a test-negative study in children

BackgroundTrivalent inactivated and live attenuated influenza vaccines (IIV3 and LAIV3) have been reformulated with an extra B strain (IIV4 and LAIV4). They were licensed based on immunogenicity and their effectiveness (VE) still must be empirically tested.MethodsChildren 1–17 years tested for influenza during 2013–16 were included and their immunization status verified. They were considered vaccinated if received ≥1 dose of an influenza vaccine ≥10 days before evaluated for a respiratory episode. Age-groups were classified as 1–4 years or 5–17 years. VE was estimated by comparing vaccination status of influenza-positive versus influenza-negative cases.Results6779 children were enrolled in the three seasons. Overall, 27.2% received an influenza vaccine (87.1% IIV3 or IIV4 and 12.9% LAIV4), and 15.6% tested positive for influenza (77.9% A). IIV3 was predominantly used in 2013–14 and IIV4 in 2014–15 and 2015–16. IIV3 and IIV4 had comparable VE over the three seasons (60%, 57% and 53%) and performed similarly against influenza A and B and both age-groups. LAIV4 performed poorly for influenza A (15%, 37% and 48%) but better for influenza B (100%, 56% and 100%), especially among children 5–17 years of age with VE = 100% (95%CI: 55, 100).ConclusionsInfluenza vaccination showed modest but consistent effectiveness over the years. The switch from IIV3 to IIV4 did not affect VE. LAIV4 did not perform as well as IIVs, yet it improved over the years and was particularly good protecting older children against influenza B. These results emphasize the regional nature of influenza and the need for local surveillance.     

Factors associated with parental acceptance of seasonal influenza vaccination for their children – A telephone survey in the adult population in Germany

IntroductionInfluenza vaccination of children with underlying chronic diseases is currently recommended in Germany, but targeting all children constitutes an alternative approach to control seasonal influenza. To inform the modelling of vaccination impact and possible communication activities, we aimed to assess among parents the acceptance of universal childhood vaccination against seasonal influenza and possible modifiers.MethodsWe conducted a telephone survey in households in Germany using random digit dialing. We interviewed parents with children aged <18 years by constructing three hypothetical scenarios in subsequent order: (1) hearing about the influenza vaccination recommendation through the media, (2) the vaccine being recommended by a physician, and (3) being informed about the availability of the vaccine as a nasal spray. We calculated the proportion of parents who would immunize their child and used univariable and multivariable logistic regression to identify factors associated with influenza vaccination intention.ResultsResponse was between 22 and 46%. Of 518 participants, 74% were female, mean age was 41.3 years. Participants had on average 1.6 children with a mean age of 8.9 years. In scenario 1, 52% of parents would immunize their child, compared to 64% in scenario 2 (p < 0.01) and to 45% in scenario 3 (p = 0.20). Factors independently associated with vaccination acceptance in scenario 1 were previous influenza vaccination of the child or parent (adjusted odds ratio [aOR] 4.5 and 8.6, respectively), perceived severity of influenza (aOR = 5.1) and living in eastern Germany (aOR = 2.4).ConclusionIf seasonal influenza vaccination was recommended for all children, more than half of the parents would potentially agree to immunize their child. Involving physicians in future information campaigns is essential to achieve high uptake. As intranasal vaccine administration is non-invasive and easily done, it remains unclear why scenario 3 was associated with low acceptance among parents, and the underlying reasons should be further explored.     

Evaluating the case-positive,control test-negative study design for influenza vaccine effectiveness for the frailty bias

IntroductionPrevious influenza vaccine effectiveness studies were criticized for their failure to control for frailty. This study was designed to see if the test-negative study design overcomes this bias.MethodsAdults ≥ 50 years of age with respiratory symptoms were enrolled from November 2006 through May 2012 during the influenza season (excluding the 2009–2010 H1N1 pandemic season) to perform yearly test-negative control influenza vaccine effectiveness studies in Nashville, TN. At enrollment, both a nasal and throat swab sample were obtained and tested for influenza by RT-PCR. Frailty was calculated using a modified Rockwood Index that included 60 variables ascertained in a retrospective chart review giving a score of 0 to 1. Subjects were divided into three strata: non frail (≤0.08), pre-frail (>0.08 to <0.25), and frail (≥0.25). Vaccine effectiveness was calculated using the formula [1-adjusted odds ratio (OR)] × 100%. Adjusted ORs for individual years and all years combined were estimated by penalized multivariable logistic regression.ResultsOf 1023 hospitalized adults enrolled, 866 (84.7%) participants had complete immunization status, molecular influenza testing and covariates to calculate frailty. There were 83 influenza-positive cases and 783 test-negative controls overall, who were 74% white, 25% black, and 59% female. The median frailty index was 0.167 (Interquartile: 0.117, 0.267). The frailty index was 0.167 (0.100, 0.233) for the influenza positive cases compared to 0.183 (0.133, 0.267) for influenza negative controls (p = 0.07). Vaccine effectiveness estimates were 55.2% (95%CI: 30.5, 74.2), 60.4% (95%CI: 29.5, 74.4), and 54.3% (95%CI: 28.8, 74.0) without the frailty variable, including frailty as a continuous variable, and including frailty as a categorical variable, respectively.ConclusionsUsing the case positive test negative study design to assess vaccine effectiveness, our measure of frailty was not a significant confounder as inclusion of this measure did not significantly change vaccine effectiveness estimates.     

Annual influenza vaccination reduces total hospitalization in patients with chronic hepatitis B virus infection: A population-based analysis

BackgroundThis study evaluated hospitalization and mortality in patients with chronic hepatitis B virus infection (HBV (+)) and matched comparison patients after stratifying the patients according to annual influenza vaccination (Vaccine (+)).MethodsData from Taiwan's National Health Insurance program from 2000 to 2009 were used to identify HBV(+)/vaccine(+) (n = 4434), HBV(+)/Vaccine(−) (n = 3646), HBV(−)/Vaccine(+) (n = 8868), and HBV(−)/Vaccine(−) (n = 8868) cohorts. The risk of pneumonia/influenza, respiratory failure, intensive care, hospitalization, and mortality in the four cohorts was evaluated.ResultsThe total hospitalization rate was significantly lower in patients with chronic HBV infection who received an annual influenza vaccination than in chronic HBV-infected patients who did not receive an influenza vaccination (16.29 vs. 24.02 per 100 person-years), contributing to an adjusted hazard ratio (HR) of 0.56 (95% confidence interval (CI) = 0.50–0.62). The HBV(+)/Vaccine(+) cohort also had lower risks than the HBV(+)/Vaccine(−) cohort for pneumonia and influenza (adjusted HR = 0.79, 95% CI = 0.67–0.92), intensive care unit admission (adjusted HR = 0.33, 95% CI = 0.25–0.43), and mortality (adjusted HR = 0.19, 95% CI = 0.15–0.24).ConclusionsOur results suggest that annual influenza vaccination can reduce the risk of hospitalization and mortality in patients with chronic HBV infection.     

Predictors of influenza vaccination in the U.S. among children 9–13 years of age

Background and objectivesU.S. estimates of seasonal influenza (flu) vaccine uptake in 2014–2015 were 62% for 5–12 year olds, dropping to 47% for 13–17 year olds. The Healthy People 2020 goal for these age groups is 80%. It is important to understand factors associated with influenza vaccination, especially for those ages where rates begin to decline. The objective of this study was to identify factors associated with influenza vaccination acceptance in 9–13 year old children.MethodsAn online U.S. survey of mothers of children aged 9–13 assessed children's influenza vaccine uptake in the previous season, healthcare utilization, sociodemographics, and vaccine attitudes. Multivariable logistic regression identified independent predictors of influenza vaccine status.ResultsThere were 2363 respondents (Mean age = 38 years old). Referent children were 57% female and 66% non-minority race/ethnicity with a mean age of 10.6 years. By maternal report, 59% of children had received an influenza vaccine in the previous season. Predictors of influenza vaccine uptake included a recommendation or strong recommendation from a health care provider, seeing a health care provider in the past year, positive attitudes regarding the influenza vaccine, and being a minority race. Child gender, age, insurance coverage, and whether the child had a regular healthcare provider were not associated with influenza vaccine uptake (p = n.s.).ConclusionsThis sample reported overall rates of influenza vaccine uptake similar to national surveillance data, but still lower than national goals. Provider recommendations along with health attitudes and seeing a health care provider were associated with vaccine uptake. Promising interventions may include more directive physician messaging for influenza vaccine uptake in youth, encouraging more regular well-child visits during the adolescent years, and promoting influenza vaccination at alternative sites.     

Seasonal influenza vaccine effectiveness against medically attended influenza illness among children aged 6–59 months,October 2011–September 2012: A matched test-negative case–control study in Suzhou,China

BackgroundSeasonal influenza infections among young children in China lead to substantial numbers of hospitalizations and financial burden. This study assessed the seasonal influenza vaccine effectiveness (VE) against laboratory confirmed medically attended influenza illness among children in Suzhou, China, from October 2011–September 2012.MethodsWe conducted a test-negative case–control study among children aged 6–59 months who sought care at Soochow University Affiliated Children's Hospital (SCH) from October 2011–September 2012. A case was defined as a child with influenza-like illness (ILI) or severe acute respiratory infection (SARI) with an influenza-positive nasopharyngeal swab by rRT-PCR. Controls were selected from children presenting with ILI or SARI without laboratory confirmed influenza. We conducted 1:1 matching by age and admission date. Vaccination status was verified from the citywide immunization system database. VE was calculated with conditional logistic regression: (1 − OR) × 100%.ResultDuring the study period, 2634 children aged 6–59 months presented to SCH with ILI (1975) or SARI (659) and were tested for influenza. The vaccination records were available for 69% (1829; ILI: 1354, SARI: 475). Among those, 23% (427) tested positive for influenza, and were included as cases. Among influenza positive cases, the vaccination rates were 3.2% for SARI and 4.5% for ILI. Among controls, the vaccination rates were 13% for SARI, and 11% for ILI. The overall VE against lab-confirmed medically attended influenza virus infection was 67% (95% CI: 41–82). The VE for SARI was 75% (95% CI: 11–93) and for ILI was 64% (95% CI: 31–82).ConclusionsThe seasonal influenza vaccine was effective against medically attended lab-confirmed influenza infection in children aged 6–59 months in Suzhou, China in the 2011–12 influenza season. Increasing seasonal influenza vaccination among young children in Suzhou may decrease medically attended influenza-associated ILI and SARI cases in this population.     

Influenza vaccination in healthcare workers; comparison of side effects and preferred route of administration of intradermal versus intramuscular administration

ObjectiveTo explore the nature and severity of side effects and future preference of intradermal versus intramuscular influenza vaccination in healthcare workers.DesignProspective cohort study.SettingTwo University Medical Centers in The Netherlands.ParticipantsHealthcare workers receiving an influenza vaccination.MethodsHealthcare workers that were vaccinated during the influenza vaccination season of 2012–2013 were approached for participation in a questionnaire study. The questionnaire was divided into two parts. The first part had to be answered directly after vaccination and the second part two weeks after vaccination. The motivation for vaccine uptake, whether or not the HCWs had direct contact with patients and the prevalence and severity of local and systemic side effects of influenza vaccination were explored. In addition, it was assessed how participants experienced the vaccination and which type of administration they preferred for future vaccination.ResultsSide effects of vaccination were more prevalent in the intradermal group versus the intramuscular group (56% versus 26%, p < 0.001). Local side effects were perceived as more severe in healthcare workers receiving the intradermal vaccine. Directly after vaccination, healthcare workers preferred the intradermal vaccination. Two weeks after vaccination both types of vaccine were equally appreciated.ConclusionsThis study shows that there are significant differences in the nature and severity of side effects upon intramuscular and intradermal influenza vaccination. This difference did not result in a preference among the vaccinated subjects for one type of vaccine.