Influenza vaccination and risk of hospitalization among adults with laboratory confirmed influenza illness

Background

Influenza vaccine is moderately effective for preventing influenza illness. It is not known if vaccination reduces the risk of subsequent hospital admission among patients with vaccine failure and laboratory confirmed influenza illness.

Methods

Patients in a community cohort presenting with acute respiratory illness were prospectively enrolled and tested for influenza during 8 seasons to estimate seasonal vaccine effectiveness. Hospital admissions within 14 days after illness onset were identified for all participants aged ≥20 years with laboratory confirmed influenza. The association between vaccination and hospital admission was examined in a propensity score adjusted logistic regression model. The model was validated by examining the association between vaccination and hospital admission in participants without influenza.

Results

Influenza was identified in 1393 (28%) of 4996 participants. Sixty-two (6%) of 1020 with influenza A and 17 (5%) of 369 with influenza B were hospitalized. Vaccination was not associated with a reduced risk of hospital admission among all participants with influenza [adjusted odds ratio (aOR) = 1.08; 95% CI: 0.62, 1.88]; or among those with influenza A (aOR = 1.35; 95% CI: 0.71, 2.57) or influenza B (aOR = 0.67; 95% CI: 0.21, 2.15). Influenza vaccination was not associated with hospitalization after non-influenza respiratory illness (aOR = 1.14; 95% CI: 0.84, 1.54).

Conclusions

Influenza vaccination did not reduce the risk of subsequent hospital admission among patients with vaccine failure. These findings do not support the hypothesis that vaccination mitigates influenza illness severity.     

Variations in influenza vaccination among the elderly

OBJECTIVES: To identify unique, mutually exclusive population segments whose members share characteristics associated with likelihood of influenza vaccination. METHODS: Data from 30,668 elderly participants in the 1999 Behavioral Risk Factor Surveillance Systems was analyzed using classification and regression tree analysis. RESULTS: Eleven subgroups were identified: Non-Hispanic Blacks and Hispanics with no recent checkup had the lowest prevalence estimate (28.1%), whereas married white persons aged 75 plus with a recent checkup had the highest (80.6%). CONCLUSIONS: Influenza vaccination varies greatly according to preventive medical care use and race/ethnicity, factors that are amenable to targeted outreach efforts.     

Evaluation of seasonal influenza vaccination effectiveness based on antibody efficacy among the institutionalized elderly in Japan

Influenza vaccination efficacy was evaluated in 114 institutionalized elderly people in 2002/03. Strain A/H3N2 was isolated; 44 and 8 subjects had sudden-onset fever (≥37.8 °C) and kit-diagnosed influenza, respectively. Odds ratios adjusted for age, sex, comorbidity, and vaccine strain (OR_adj) were determined using multiple logistic regression. Seroprotected patients (haemagglutination-inhibition antibody titre ≥1:40) had lower incidence of fever (OR_adj, 0.35; 95% confidence interval [CI], 0.09–1.28) and kit-diagnosed influenza (OR_adj, 0.35; 95% CI, 0.03–4.64) than patients without seroprotection (antibody efficacy, ∼65%). Seroprotective levels of vaccination-induced antibodies probably prevent influenza among the institutionalized elderly, although statistical significance could not be confirmed owing to the sample size.     

Cost-effectiveness of seasonal inactivated influenza vaccination among pregnant women

ObjectiveTo evaluate the cost-effectiveness of seasonal inactivated influenza vaccination among pregnant women using data from three recent influenza seasons in the United States.Design, setting, and participantsWe developed a decision-analytic model following a cohort of 5.2 million pregnant women and their infants aged <6 months to evaluate the cost-effectiveness of vaccinating women against seasonal influenza during pregnancy from a societal perspective. The main outcome measures were quality-adjusted life-year (QALY) gained and cost-effectiveness ratios. Data sources included surveillance data, epidemiological studies, and published vaccine cost data. Sensitivity analyses were also performed. All costs and outcomes were discounted at 3% annually.Main outcome measuresTotal costs (direct and indirect), effects (QALY gains, averted case numbers), and incremental cost-effectiveness of seasonal inactivated influenza vaccination among pregnant women (cost per QALY gained).ResultsUsing a recent benchmark of 52.2% vaccination coverage among pregnant women, we studied a hypothetical cohort of 2,753,015 vaccinated pregnant women. With an estimated vaccine effectiveness of 73% among pregnant women and 63% among infants <6 months, QALY gains for each season were 305 (2010–2011), 123 (2011–2012), and 610 (2012–2013). Compared with no vaccination, seasonal influenza vaccination during pregnancy was cost-saving when using data from the 2010–2011 and 2012–2013 influenza seasons. The cost-effectiveness ratio was greater than $100,000/QALY with the 2011–2012 influenza season data, when CDC reported a low attack rate compared to other recent seasons.ConclusionsInfluenza vaccination for pregnant women can reduce morbidity from influenza in both pregnant women and their infants aged <6 months. Seasonal influenza vaccination during pregnancy is cost-saving during moderate to severe influenza seasons.     

Intrinsic defects in B cell response to seasonal influenza vaccination in elderly humans

We have evaluated the serum response to seasonal influenza vaccination in subjects of different ages and associated this with the specific B cell response to the vaccine in vitro. Although the serum response has previously been shown to decrease with age, this has largely been associated to decreased T cell functions. Our results show that in response to the vaccine, the specific response of B cells in vitro, as measured by AID (activation-induced cytidine deaminase), the in vivo serum HI (hemagglutination inhibition) response, and the in vivo generation of switch memory B cells are decreased with age, as evaluated in the same subjects. This is the first report to demonstrate that intrinsic B cell defects with age contribute to reduced antibody responses to the influenza vaccine. The level of AID in response to CpG before vaccination can also predict the robustness of the vaccine response. These results could contribute to developing more effective vaccines to protect the elderly as well as identifying those most at risk.     

Factors associated with influenza vaccination among elderly Spanish women

OBJECTIVES: Influenza vaccination is an effective intervention to diminish morbidity and mortality associated with this disease in aged populations and at-risk groups. The objective of this work was to describe population patterns of vaccination among Galician women and to identify factors associated with vaccination. STUDY DESIGN: Cross-sectional study. METHODS: Cases aged 65 years and over were selected from the Women's Social and Health Interview, Galicia 2000 (n = 1111). The association between influenza vaccination last season and several sociodemographic, lifestyle, health status and health services variables was assessed by logistic regression. RESULTS: In total, 56.3% of cases had received the influenza vaccine. The following variables were significantly associated with vaccination: age 70-74 years (odds ratios, OR=1.56; 95% CI: 1.09-2.26); age> or =75 years (OR=1.88; 95% CI: 1.31-2.71); residence in towns with 5000-20,000 inhabitants (OR=1.79; 95% CI: 1.16-2.77); annual income 6.010 (OR=1.39; 95% CI: 1.01-1.90); unfavourable self-perception of health (OR=1.46; 95% CI: 1.06-2.00); not being a caregiver (OR=1.67; 95% CI: 1.17-2.38); married (OR=1.45; 95% CI: 1.05-2.01); tetanus vaccination (OR=1.43; 95% CI: 1.07-1.93); and visiting a physician in the last 2 years (OR=4.83; 95% CI: 2.61-8.93). CONCLUSIONS: The level of vaccination among Galician women is low, although it is higher than that in Spanish women overall. This work has identified groups of women who are less likely to be vaccinated, and who should be targeted in future vaccination campaigns.     

Impact of rotavirus vaccination on laboratory confirmed cases in Belgium

Rotavirus vaccines were introduced in Belgium in 2006 and recommended in the universal schedule in January 2007. We measured the impact of rotavirus vaccination through an active laboratory-based surveillance system. In 2008, the number of laboratory confirmed rotavirus cases declined by 61.4% (95% CI 60.2-62.6%) compared to the 2005-2006 pre-vaccination period, with the highest decline in children<1 year (80.1%; 95% CI 78.7-81.4%). The rotavirus season was delayed compared to pre-vaccination seasons. Laboratory data provide a crude estimation of vaccination impact, but analysis of in-patient data will be needed to assess the impact on severe disease.     

Factors associated with influenza vaccination among elderly persons in Southeastern Brazil

OBJECTIVE: Even though influenza vaccination is free and widely available in Brazil since 1999, coverage is still inadequate in several of the country's municipalities. The aim of the present study was to estimate vaccine coverage and to identify factors related to vaccination against influenza in the elderly population. METHODS: A household survey was carried out using a systematic random sample (N=365) of the urban population older than 60 years from the city of Botucatu, Southeastern Brazil. A logistic regression model using vaccination in 2002 as the dependent variable was used. The following covariables were tested: sex, age, socioeconomic variables (per capita income, number of persons per dormitory, schooling, marital status, occupation, time living in the city), history of morbidity and hospital admission, smoking, respiratory symptoms in last 15 days, and community activities (voluntary work, neighborhood and church activities). RESULTS: Vaccine coverage was 63.2% (95% CI: 58.3-68.2). We found a lower proportion of vaccination among the 60-64 years age group. Variables associated with vaccination in the final model were age (OR=1.09 per year; 95% CI: 1.06-1.13); arterial hypertension (OR=1.92; 95% CI: 1.18-3.13); and participation in community activities (OR=1.63; 95% CI: 1.01-2.65). With the exception of hypertension, vaccination among subjects with chronic diseases did not reach adequate levels, as expected for this high-risk group. Participation in social and community activities was associated with vaccination status. CONCLUSIONS: Socioeconomic conditions, habits, and age did not restrict access to vaccination campaigns. On the other hand, specific campaigns aimed at the 60-64 years age group may increase vaccination coverage.     

Decomposing racial/ethnic disparities in influenza vaccination among the elderly

While persistent racial/ethnic disparities in influenza vaccination have been reported among the elderly, characteristics contributing to disparities are poorly understood. This study aimed to assess characteristics associated with racial/ethnic disparities in influenza vaccination using a nonlinear Oaxaca–Blinder decomposition method. We performed cross-sectional multivariable logistic regression analyses for which the dependent variable was self-reported receipt of influenza vaccine during the 2010–2011 season among community dwelling non-Hispanic African–American (AA), non-Hispanic White (W), English-speaking Hispanic (EH) and Spanish-speaking Hispanic (SH) elderly, enrolled in the 2011 Medicare Current Beneficiary Survey (MCBS) (un-weighted/weighted N = 6,095/19.2million). Using the nonlinear Oaxaca–Blinder decomposition method, we assessed the relative contribution of seventeen covariates – including socio-demographic characteristics, health status, insurance, access, preference regarding healthcare, and geographic regions – to disparities in influenza vaccination. Unadjusted racial/ethnic disparities in influenza vaccination were 14.1 percentage points (pp) (W–AA disparity, p < 0.001), 25.7 pp (W–SH disparity, p < 0.001) and 0.6 pp (W–EH disparity, p > .8). The Oaxaca–Blinder decomposition method estimated that the unadjusted W–AA and W–SH disparities in vaccination could be reduced by only 45% even if AA and SH groups become equivalent to Whites in all covariates in multivariable regression models. The remaining 55% of disparities were attributed to (a) racial/ethnic differences in the estimated coefficients (e.g., odds ratios) in the regression models and (b) characteristics not included in the regression models. Our analysis found that only about 45% of racial/ethnic disparities in influenza vaccination among the elderly could be reduced by equalizing recognized characteristics among racial/ethnic groups. Future studies are needed to identify additional modifiable characteristics causing disparities in influenza vaccination.     

Physician and practice factors related to influenza vaccination among the elderly

BACKGROUND: Influenza vaccination rates among adults, especially in minority populations, remain below national goals of 90%. This study investigated in diverse settings, facilitators of and barriers to patient influenza vaccination from the physician's perspective. METHODS: Two-stage, stratified, random-cluster sampling was employed to select 71 clinicians from inner-city, rural, suburban, and Veterans Affairs (VA) practices, and a random sample of 925 of their patients aged >/=65 years. Questionnaires and interviews based on the PRECEDE-PROCEED framework assessed clinician factors. Associations among clinician beliefs, practice characteristics, patient beliefs, and self-reported influenza vaccination status were determined. RESULTS: The clinician response rate was 85% (60/71). Several factors of the PRECEDE-PROCEED framework were associated with higher influenza vaccination rates. For instance, patients at practices with express vaccination clinics had higher vaccination rates than at clinics without such immunization programs (87% v 76%, p =0.01). Using multivariate models, influenza vaccination status was related to several patient factors, including plans to receive influenza vaccination next year (p <0.001); belief that those who are not vaccinated will contract influenza (p =0.049); and history of being screened for colon cancer (p =0.023). Influenza vaccination status was also related to several physician factors, including awareness of recommendation to vaccinate asthmatics (p =0.024); agreement with these recommendations (p =0.004); and practice type and setting ("strata"), of which the VA was highest. CONCLUSION: Through proactive office systems and education, physicians may influence patients' intentions to be vaccinated and thereby increase influenza vaccination rates.     

Interventions to increase the uptake of seasonal influenza vaccination among pregnant women: A systematic review

BackgroundPregnant women and their infants under 6 months of age infected with influenza have a high risk of serious morbidity and mortality. Influenza vaccine during pregnancy offers 3-for-1 benefits to pregnant women, fetuses and newborn infants. Current vaccination uptake rates during pregnancy, however, are often lower than other high-risk groups and the general population.MethodsWe systematically reviewed evidence on the effectiveness of interventions to improve influenza vaccination coverage in pregnant women. Risk differences (RDs) were calculated from the included studies.ResultsEleven studies were included in the review, of which four were randomized controlled trials (RCTs). Three cohort studies assessed provider-focused interventions while four RCTs and one cohort study evaluated pregnant women-focused interventions. Two cohort studies and a prospective intervention study assessed the effectiveness of bundled interventions. No study solely assessed the effectiveness of interventions to enhance access to influenza vaccination. One moderate quality RCT showed that an influenza pamphlet, with or without a verbalized benefit statement, improved the vaccination rate (RD = 0.26; RD = 0.39). The other reviewed RCTs showed discordant results, with RDs ranging from −0.15 to 0.03. Although all observational studies significantly improved vaccination rates (RDs ranged from 0.03 to 0.44), the quality of the evidence varied.ConclusionsThere is a lack of effective interventions to increase the influenza vaccination rate in pregnant women. Based on the existing research, we recommend that clinicians provide influenza pamphlets to pregnant women with a verbalized statement about the benefits of influenza vaccine to newborns. Further high-quality RCTs are needed to develop successful maternal influenza vaccination programs. Increased clarity in reporting the content of interventions would help to improve the comparability and generalizability of the published studies.     

An analysis of the demand for influenza vaccination among the elderly in Japan

PURPOSE: This paper will discuss an analysis of the demand for vaccination for the elderly as a high-risk group. Influence of the governmental endorsement and/or subsidy on these demand is, then, evaluated from the estimation results. METHODS: Original data were obtained from two surveys conducted by the author for the elderly living with and without descendents. Information was collected about the elderly themselves, the household, experience of influenza and immunization in the last season, and the hypothetical questionnaire about immunization was answered by each respondent to be applied for Conjoint Analysis. Three estimations are performed for the actual behavior, Conjoint Analysis and the joint estimation of these two methods. RESULTS: Experience of influenza and immunization in the last season, proved to be two of the most important determinants. Among the others estimated parameters, cost of immunization, the number of immunization to complete for effectiveness, availability of the immunization at night or on a weekend, and the governmental endorsement greatly affected the immunization demand. Moreover, the superiority of the statistical properties of the joint estimation was confirmed. CONCLUSIONS: The estimation results imply that about 8.9 million elderly people would demand vaccination if there was no cost and there was a governmental endorsement. This would be reduced to be 3.2 million if the cost was 6,000 yen (about 50 dollars) and there was no governmental endorsement. Governmental endorsement alone would increase the number by 2.0 million. The change from no cost to only 500 yen (about 4 dollars) would depress the demand by 1.6 million.     

北京市丰台区老年人免费流感疫苗接种效果评价

目的 评价北京市丰台区老年人接种免费流感疫苗的效果。方法 随机抽取丰台区2019年10—11月434名接种免费流感疫苗的60周岁以上的老年人作为接种组,选取2019年未接种流感疫苗的60周岁以上的434名老年人作为对照组。采用统一设计的调查问卷,收集调查对象的基本情况、接种疫苗后一年内流感样病例、呼吸系统疾病和心脑血管疾病的发生及就诊情况。结果 接种免费流感疫苗3个月内,接种组流感样病例的发病率(1.61%)低于对照组的发病率(5.07%),差异有统计学意义(χ²=8.027,P=0.005)。接种免费流感疫苗3个月内、4～6个月、7～12个月流感样病例的保护率分别为68.24%、16.67%、25.00%,流感样病例就医行为的保护率分别为40.00%、25.00%、50.00%;呼吸系统疾病的保护率分别为25.45%、-29.93%、-67.03%,呼吸系统疾病就医行为的保护率分别为19.97%、-8.70%、-57.14%;心脑血管系统疾病的保护率分别为40.00%、16.67%、-25.00%,心脑血管系统疾病就医行为的保护率分别为60.00%、75.00%...