The impacts of email reminder/recall on adolescent influenza vaccination

BackgroundWe sought to: (1) explore the feasibility of using email for seasonal influenza vaccination reminders to parents of adolescents and (2) assess influenza vaccination rates among adolescents whose parents were randomized to either receive or not receive email reminders.MethodsEmail addresses were obtained for parents of patients 10–18 years from 4 practices in Michigan. Addresses were randomized to either receive email reminders, or not. Reminder messages were sent during October 2012-March 2013 (Season 1) and October 2013-March 2014 (Season 2). Vaccination status was determined 60 days following the last email reminder for each season using the statewide Michigan Care Improvement Registry (MCIR); per protocol bivariate and multivariate logistic regression analyses were conducted to evaluate reminder notification.ResultsAfter email cleaning, testing, and matching with MCIR, approximately half of email addresses (2348 of 5312 in Season 1; 3457 of 6549 in Season 2) were randomized. Bivariate analyses found that influenza vaccination within 60 days after notification date was similar among those notified (34%) versus not notified (29%) in both Season 1 (p = 0.06) and Season 2 (39% vs. 37%, p = 0.20). However, multivariate models adjusted for season, site, and receipt of notification in two seasons found a higher likelihood of influenza vaccination among children that received notification (aOR = 1.28, 95% CI = 1.09, 1.51); in addition, differences in influenza vaccination were also observed between practice sites (range: p = 0.15 to p < 0.001).ConclusionsWe found that practice-based email influenza vaccine reminders to parents of adolescents are feasible, but not without complications. Our study demonstrates that email reminders from practices can yield increases in influenza vaccination rates among adolescents. Practices should consider email as an option for influenza reminders and establish business practices for collecting and maintaining patient email addresses.This study is registered at www.ClinicalTrials.gov id #NCT01732315.     

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.     

Near real-time surveillance for Guillain-Barré syndrome after influenza vaccination among the Medicare population, 2010/11 to 2013/14

BackgroundGuillain-Barré syndrome (GBS) is a serious acute demyelinating disease that causes weakness and paralysis. The Food and Drug Administration (FDA) began collaborating with the Centers for Medicare and Medicaid Services (CMS) to develop near real-time vaccine safety surveillance capabilities in 2006 and has been monitoring for the risk of GBS after influenza vaccination for every influenza season since 2008.MethodsWe present results from the 2010/11 to 2013/14 influenza seasons using the Updating Sequential Probability Ratio Test (USPRT), with an overall 1-sided α of 0.05 apportioned equally using a constant alpha-spending plan among 20 consecutive weekly tests, 5 ad hoc tests, and a 26th final end of season test. Observed signals were investigated using the self-controlled risk interval (SCRI) design.ResultsOver 15 million people were vaccinated in each influenza season. In the 2010/11 influenza season, we observed an elevated GBS risk during the season, with an end of season SCRI analysis finding a nonsignificant increased risk (RR = 1.25, 95% CI: 0.96–1.63). A sensitivity analysis applying the positive predictive value of the ICD-9 code for GBS from the 2009/10 season estimated a RR = 1.98 (95% CI: 1.42–2.76). Although the 2010/11 influenza vaccine suggested an increased GBS risk, surveillance of the identical vaccine in the 2011/12 influenza season did not find an increased GBS risk after vaccination. No signal was observed in the subsequent three influenza seasons.ConclusionsConducting near real-time surveillance using USPRT has proven to be an excellent method for near real-time GBS surveillance after influenza vaccination, as demonstrated by our surveillance efforts during the 2010/11–2013/14 influenza seasons. In the 2010/2011 influenza season, in addition to the 2009 H1N1 influenza pandemic, using near real-time surveillance we were able to observe a signal early in the influenza season and the method has now become routine.     

Repeated seasonal influenza vaccination among elderly in Europe: Effects on laboratory confirmed hospitalised influenza

In Europe, annual influenza vaccination is recommended to elderly. From 2011 to 2014 and in 2015–16, we conducted a multicentre test negative case control study in hospitals of 11 European countries to measure influenza vaccine effectiveness (IVE) against laboratory confirmed hospitalised influenza among people aged ≥65 years. We pooled four seasons data to measure IVE by past exposures to influenza vaccination.We swabbed patients admitted for clinical conditions related to influenza with onset of severe acute respiratory infection ≤7 days before admission. Cases were patients RT-PCR positive for influenza virus and controls those negative for any influenza virus. We documented seasonal vaccination status for the current season and the two previous seasons.We recruited 5295 patients over the four seasons, including 465A(H1N1)pdm09, 642A(H3N2), 278 B case-patients and 3910 controls. Among patients unvaccinated in both previous two seasons, current seasonal IVE (pooled across seasons) was 30% (95%CI: −35 to 64), 8% (95%CI: −94 to 56) and 33% (95%CI: −43 to 68) against influenza A(H1N1)pdm09, A(H3N2) and B respectively. Among patients vaccinated in both previous seasons, current seasonal IVE (pooled across seasons) was −1% (95%CI: −80 to 43), 37% (95%CI: 7–57) and 43% (95%CI: 1–68) against influenza A(H1N1)pdm09, A(H3N2) and B respectively.Our results suggest that, regardless of patients’ recent vaccination history, current seasonal vaccine conferred some protection to vaccinated patients against hospitalisation with influenza A(H3N2) and B. Vaccination of patients already vaccinated in both the past two seasons did not seem to be effective against A(H1N1)pdm09. To better understand the effect of repeated vaccination, engaging in large cohort studies documenting exposures to vaccine and natural infection is needed.     

Social and demographic patterns of influenza vaccination coverage in Norway,influenza seasons 2014/15 to 2020/21

AimsTo examine influenza vaccination coverage among risk groups (RG) and health care workers (HCW), and study social and demographic patterns of vaccination coverage over time.MethodsVaccination coverage was estimated by self-report in a nationally representative telephone survey among 14 919 individuals aged 18–79 years over seven influenza seasons from 2014/15 to 2020/21. We explored whether belonging to an influenza RG (being >=65 years of age and/or having >=1 medical risk factor), being a HCW or educational attainment was associated with vaccination status using logistic regression.ResultsVaccination coverage increased from 27 % to 66 % among individuals 65–79 years, from 13 % to 33 % among individuals 18–64 years with >=1 risk factor, and from 9 % to 51 % among HCWs during the study period. Being older, having a risk factor or being a HCW were significantly associated with higher coverage in all multivariable logistic regression analyses. Higher education was also consistently associated with higher coverage, but the difference did not reach significance in all influenza seasons. Educational attainment was not significantly associated with coverage while coverage was at its lowest (2014/15–2017/18), but as coverage increased, so did the differences. Individuals with intermediate or lower education were less likely to report vaccination than those with higher education in season 2018/19, OR = 0.61 (95 % CI 0.46–0.80) and OR = 0.58 (95 % CI 0.41–0.83), respectively, and in season 2019/20, OR = 0.69 (95 % CI 0.55–0.88) and OR = 0.71 (95 % CI 0.53–0.95), respectively. When the vaccine was funded in the COVID-19 pandemic winter of 2020/21, educational differences diminished again and were no longer significant.ConclusionsWe observed widening educational differences in influenza vaccination coverage as coverage increased from 2014/15 to 2019/20. When influenza vaccination was funded in 2020/21, differences in coverage by educational attainment diminished. These findings indicate that economic barriers influence influenza vaccination decisions among risk groups in Norway.     

Improving influenza and Tdap vaccination during pregnancy: A cluster-randomized trial of a multi-component antenatal vaccine promotion package in late influenza season

BackgroundEvidence-based interventions to improve influenza vaccine coverage among pregnant women are needed, particularly among those who remain unvaccinated late into the influenza season. Improving rates of antenatal tetanus, diphtheria and acellular pertussis (Tdap) vaccination is also needed.PurposeTo test the effectiveness of a practice-, provider-, and patient-focused influenza and Tdap vaccine promotion package on improving antenatal influenza and Tdap vaccination in the obstetric setting.MethodsA cluster-randomized trial among 11 obstetric practices in Georgia was conducted in 2012–2013. Intervention practices adopted the intervention package that included identification of a vaccine champion, provider-to-patient talking points, educational brochures, posters, lapel buttons, and iPads loaded with a patient-centered tutorial. Participants were recruited from December 2012–April 2013 and included 325 unvaccinated pregnant women in Georgia. Random effects regression models were used to evaluate primary and secondary outcomes.ResultsData on antenatal influenza and Tdap vaccine receipt were obtained for 300 (92.3%) and 291 (89.5%) women, respectively. Although antenatal influenza and Tdap vaccination rates were higher in the intervention group than the control group, improvements were not significant (For influenza: risk difference (RD) = 3.6%, 95% confidence interval (CI): −4.0%, 11.2%; for Tdap: RD = 1.3%, 95% CI: −10.7%, 13.2%). While the majority of intervention package components were positively associated with antenatal vaccine receipt, a provider's recommendation was the factor most strongly associated with actual receipt, regardless of study group or vaccine.ConclusionsThe intervention package did not significantly improve antenatal influenza or Tdap vaccine coverage. More research is needed to determine what motivates women remaining unvaccinated against influenza late into the influenza season to get vaccinated. Future research should quantify the extent to which clinical interventions can bolster a provider's recommendation for vaccination. This study is registered with clinicaltrials.gov, study ID NCT01761799.     

Antibody persistence and serological protection among seasonal 2007 influenza A(H1N1) infected subjects: Results from the FLUREC cohort study

IntroductionHaemagglutination-inhibition (HI) antibody titer is a correlate of protection against influenza; its persistence after infection or vaccination is important to determining susceptibility to subsequent infection. Few studies, however, have reported longitudinal data regarding the magnitude and duration of HI protection following natural seasonal influenza A infection.MethodsUsing French influenza cohort study data collected from 2008 to 2010, we investigated persistence of serological protection among subjects according to influenza-like illness (ILI) and laboratory-confirmed seasonal 2007 influenza A(H1N1) infection status at inclusion in 2008 (ILI-A(H1N1) positive, ILI-A(H1N1) negative, or no-ILI). Antibody titers against seasonal 2007 A(H1N1) were determined using the HI technique for sera. Regression models for interval-censored data were used to estimate geometric mean titers (GMT) for HI assays. A logistic regression model adjusted for age group (subjects <30, 30–50 and >50 years old) was used to quantify the association between HI titer and protection against infection.ResultsBased on 310 total subjects, influenza A(H1N1) infection was confirmed in 39 of 115 ILI subjects at inclusion. GMT associated with 50% probability of protection among ILI subjects decreased with age group (subjects <30 yo: GMT of 40.8 was associated with 50% [95CI: 29.3%; 70.7%] probability of protection, subjects 30–50 yo: 26.8 [95CI: 34.4%; 65.6%] and subjects >50 yo: 8.9 [95CI: 15.3%; 84.7%]). GMT declined after the first annual study visit among ILI-A(H1N1) positive subjects but remained higher compared to inclusion at the 2010 study visit (41.5 [95CI: 34.8; 49.5], p = 0.0157). GMT remained stable among ILI-A(H1N1) negative subjects (p = 0.7502), but decreased among no-ILI subjects (p < 0.0001).ConclusionOur results confirm the positive relationship between HI titer and probability of protection among naturally infected subjects, and provides evidence that protection associated with HI titer varies with age. This longitudinal analysis suggests the rise in HI titers following seasonal 2007 influenza A(H1N1) infection may persist into subsequent influenza seasons.     

Trends in reasons for non-receipt of influenza vaccination during pregnancy in Georgia, 2004–2011

BackgroundConsiderable research has identified barriers to antenatal influenza vaccination, yet no research has explored temporal trends in reasons for non-receipt.PurposeTo examine trends in reasons for non-receipt of influenza vaccination during pregnancy.MethodsSerial cross-sectional analyses using 8 years of Georgia Pregnancy Risk Assessment Monitoring Survey (PRAMS) data were conducted. Weighted logistic regression was used to examine trends in the prevalence of citing reasons for non-receipt over time.ResultsBetween 2004 and 2011, 8300 women reported no influenza vaccination during or immediately before pregnancy. Proportions of women citing “doctor didn’t mention vaccination,” “in first trimester during influenza season,” and “not pregnant during influenza season” decreased significantly over time (Doctor didn’t mention: 48.0% vs. 27.1%, test for trend p < 0.001; in first trimester: 26.8% vs. 16.3%, test for trend p < 0.001; not influenza season: 24.2% vs. 12.7%, test for trend p = 0.001). Safety concerns increased over 2004 proportions in 2010 (concern about side effects for me: 40.2% vs. 28.5%, prevalence ratio (PR): 1.41, 95% confidence interval (CI): 1.16, 1.71; concern about harming my baby: 38.9% vs. 31.0%, PR = 1.26, 95% CI: 1.04, 1.53) and 2011 (concern about side effects for me: 39.0% vs. 28.5%, PR = 1.37, 95% CI: 1.13, 1.65; concern about harming my baby: 38.8% vs. 31.0%, PR = 1.25, 95% CI: 1.04, 1.50). Following the 2009/2010 H1N1 pandemic, more Hispanic women cited concern about vaccination harming their baby than other women; in 2011, their concern remained elevated relative to non-Hispanic white women (63% vs. 35%; adjusted PR = 1.79, 95% CI: 1.23, 2.61).ConclusionExamining trends in reasons for non-receipt of antenatal influenza vaccination can reflect successes related to vaccine promotion and areas for improvement. By highlighting differential impacts of the 2009/2010 H1N1 pandemic, we reveal opportunities for additional research on tailoring vaccine promotion efforts to specific types of women.     

Negative impact of prior influenza vaccination on current influenza vaccination among people infected and not infected in prior season: A test-negative case-control study in Japan

BackgroundAccumulating evidences indicate that repeated influenza vaccination has negative impact on the vaccine effectiveness (VE). However no published studies considered past influenza infection when assessing the VE of repeated vaccination.MethodsProspective surveillance was conducted from 2009 to 2012 at a community hospital on a small island in Japan. The study included all outpatients with an influenza-like illness (ILI) who attended the hospital, and a rapid diagnostic test (RDT) was used to diagnose influenza A/B infection. The VE of trivalent inactivated influenza vaccine (TIV) against medically attended influenza A (MA-fluA) was estimated using a test-negative case-control study design. The influence of TIV in the prior season on VE in the current season was investigated in the context of MA-fluA during the prior season.ResultsDuring the three influenza seasons, 5838 ILI episodes (4127 subjects) were analysed. Subjects who had an episode of MA-fluA in the prior season were at a significantly lower risk of MA-fluA in the current season (adjusted odds ratio: 0.38, 95% CI: 0.30–0.50). The overall adjusted VE was 28% (95% CI, 14–40). VE was substantially lower in subjects vaccinated in the prior season compared to those who had not been vaccinated in prior season (19%; 95% CI: 0–35 vs 46%; 95% CI: 26–60, test for interaction, P value <0.05). In subjects who did not have MA-fluA in the prior season showed the attenuation of VE due to repeated vaccination (13%; 95% CI: −7 to 30 vs 44%; 95% CI: 24–59, test for interaction, P < 0.05). However this effect was not detected in subjects who had contracted MA-fluA in the prior season.ConclusionsNegative effects of repeated vaccination were significant among those without history of MA-fluA in the prior season.     

Influenza vaccination rates in children decline when the live attenuated influenza vaccine is not recommended

BackgroundIn 2016 the Centers for Disease Control and Prevention (CDC) recommended against using the live attenuated influenza vaccine (LAIV) for the 2016–2017 influenza season. This recommendation is potentially important for vaccination rates because perceived effectiveness and ease of administration are among the primary determinants of families decisions to vaccinate their children. This investigation sought to determine whether rates of pediatric influenza vaccination changed in a season when the LAIV was not recommended.MethodsThis study used cohort and cross sectional data from an academic primary care pediatric center in central Pennsylvania that serves approximately 12,500 patients. Early season (prior to November 1) and end-of-season (prior to March 1) vaccination rates in the 2015–16 and 2016–17 influenza seasons were recorded for individuals 2–17 years old. Repeat vaccination rates (percentage of children receiving influenza vaccination in one season who were also vaccinated in the next season) were recorded for the 2015–16 into 2016–17 seasons. A logistic regression model adjusting for race, ethnicity, age, insurance type and type of vaccination received was employed to identify predictors of repeat vaccination.ResultsIn the absence of LAIV (2016–17) early vaccination rates were significantly higher (24.7% vs 22.8%, p = 0.004), but end-of-season rates were lower (50.4% vs 52.0%, p = 0.03) than when LAIV was offered (2015–16). After adjusting for covariates, those who had received IIV in the 2015–16 season had higher odds (OR 1.32, 95% CI, 1.15–1.52) of getting a repeat vaccination in the 2016–17 season, compared with those who had received LAIV in the 2015–16 season.ConclusionsEnd-of-season vaccination rates were lower in 2016–17 when LAIV was not recommended, particularly among children who received LAIV in the preceding year. Unavailability of LAIV in the 2016–17 season may have impacted influenza vaccination convenience and perceived effectiveness, two factors which could influence vaccine uptake in pediatric populations.     

Association of spontaneous abortion with receipt of inactivated influenza vaccine containing H1N1pdm09 in 2010–11 and 2011–12

IntroductionInactivated influenza vaccine is recommended in any stage of pregnancy, but evidence of safety in early pregnancy is limited, including for vaccines containing A/H1N1pdm2009 (pH1N1) antigen. We sought to determine if receipt of vaccine containing pH1N1 was associated with spontaneous abortion (SAB).MethodsWe conducted a case-control study over two influenza seasons (2010–11, 2011–12) in the Vaccine Safety Datalink. Cases had SAB and controls had live births or stillbirths and were matched on site, date of last menstrual period, and age. Of 919 potential cases identified using diagnosis codes, 485 were eligible and confirmed by medical record review. Exposure was defined as vaccination with inactivated influenza vaccine before the SAB date; the primary exposure window was the 1–28 days before the SAB.ResultsThe overall adjusted odds ratio (aOR) was 2.0 (95% CI, 1.1–3.6) for vaccine receipt in the 28-day exposure window; there was no association in other exposure windows. In season-specific analyses, the aOR in the 1–28 days was 3.7 (95% CI 1.4–9.4) in 2010–11 and 1.4 (95% CI 0.6–3.3) in 2011–12. The association was modified by influenza vaccination in the prior season (post hoc analysis). Among women who received pH1N1-containing vaccine in the previous influenza season, the aOR in the 1–28 days was 7.7 (95% CI 2.2–27.3); the aOR was 1.3 (95% CI 0.7–2.7) among women not vaccinated in the previous season. This effect modification was observed in each season.ConclusionSAB was associated with influenza vaccination in the preceding 28 days. The association was significant only among women vaccinated in the previous influenza season with pH1N1-containing vaccine. This study does not and cannot establish a causal relationship between repeated influenza vaccination and SAB, but further research is warranted.     

Prevalence and associated factors of seasonal influenza vaccination among 24- to 59-month-old children in Hong Kong

BackgroundInfluenza results in severe complications among 24- to 59-month-old children, who are recommended by the WHO to take up influenza vaccination (IV) annually. Health promotion is warranted. Yet, there is a dearth of studies on IV prevalence and associated factors in this age group.MethodsA random population-based telephone survey interviewed 540 parents of Chinese children aged 24–59 months in Hong Kong during March through June, 2011. Constructs of the Health Belief Model (HBM) and subjective norm formed basis for assessing parental perceptions on influenza and IV. For data analysis, adjusted, and stepwise multiple logistic regression models were fit.ResultsThe prevalence of having taken up at least one dose and two doses of IV among children aged 24–59 months was 58.9 and 42.4%, respectively. Significant associated factors included family members’ IV experience (ORu = 5.37, 95% CI: 3.48, 8.29), variables related to the HBM constructs (except perceived severity) [perceived susceptibility of seasonal influenza (ORu = 2.03, 95% CI: 1.39, 2.95), perceived benefits of IV (ORu = 3.11, 95% CI: 2.05, 4.71), perceived barriers (ORu = 0.49, 95% CI: 0.25, 0.96) of IV, and cue to action (ORu = 4.79, 95% CI: 2.87, 7.99)], supportive subjective norm (ORu = 4.26, 95% CI: 2.91, 6.25), and level of fear felt during the H1N1 pandemic (ORu = 1.97, 95% CI: 1.01, 3.87). Adjusted for the child's age, the same significant factors were found. Exposure to related media messages was statistically non-significant.ConclusionThe reported IV prevalence was higher than that of 24- to 59-month-old children reported in other studies. There is room for improvement through health promotion, which should modify parental cognitions related to HBM (except perceived severity and self-efficacy) and involve family members to create subjective norm. Media campaigns may be inadequate for promotion of IV; use of the setting approach may be considered.     

No association between influenza vaccination during pregnancy and adverse birth outcomes

BackgroundPregnant women are recommended to receive inactivated influenza vaccination anytime during pregnancy. Studies have investigated the impact of influenza vaccination during pregnancy on birth outcomes and results on preterm birth have been inconsistent.MethodsWe conducted a retrospective cohort study among children born at a gestational age ≥ 24 weeks from January 1, 2010 to December 31, 2015 at Kaiser Permanente Northern California facilities (KPNC). We evaluated the association between maternal influenza vaccination during pregnancy and risk of preterm birth, small and large for gestational age, admission to the neonatal intensive care unit (NICU), respiratory distress syndrome, low birth weight, and low Apgar score. We ascertained the dates of maternal influenza vaccination, conception, and delivery, as well as birth outcomes from KPNC inpatient and outpatient databases. Conditional multivariate Cox regression and logistic regression analyses were used to determine the association between maternal vaccination during pregnancy and risk of each birth outcome.ResultsThe study included 145,869 children. Maternal influenza vaccination during pregnancy was not associated with risk of small or large for gestational age births, preterm birth, need for mechanical ventilation at birth, respiratory distress syndrome, admission to the NICU, low birth weight, or low Apgar score. However, when we did not control for immortal time bias, the risk of preterm birth (odds ratio [OR] = 0.69, 95% confidence interval [CI] 0.66–0.72) was lower among infants of vaccinated mothers.ConclusionWe found no association between maternal influenza vaccination during pregnancy and adverse birth outcomes. When investigating preterm birth outcome in association with vaccination during pregnancy, immortal time bias should be taken into account in the analysis.     

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.     

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.     

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 reported influenza vaccination in HIV-infected women in the United States, 2006–2007 and 2007–2008 seasons

ObjectiveTo estimate the cumulative incidence of self-reported influenza vaccination (“vaccination coverage”) and investigate predictors in HIV-infected women.MethodsIn an ongoing cohort study of HIV-infected women in five US cities, data from two influenza seasons (2006–2007 n = 1209 and 2007–2008 n = 1161) were used to estimate crude and adjusted prevalence ratios (aPR) and 95% confidence intervals ([,]) from Poisson regression with robust variance models using generalized estimating equations (GEE).ResultsIn our study, 55% and 57% of HIV-infected women reported vaccination during the 2006–2007 and 2007–2008 seasons, respectively. Using data from both seasons, older age, non-smoking status, CD4 T-lymphocyte (CD4) count ≥ 200 cells/mm³, and reporting at least one recent healthcare visit was associated with increased vaccination coverage. In the 2007–2008 season, a belief in the protection of the vaccine (aPR = 1.38 [1.18, 1.61]) and influenza vaccination in the previous season (aPR = 1.66 [1.44, 1.91]) most strongly predicted vaccination status.ConclusionInterventions to reach unvaccinated HIV-infected women should focus on changing beliefs about the effectiveness of influenza vaccination and target younger women, current smokers, those without recent healthcare visits, or a CD4 count < 200 cells/mm³.