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Background: Despite the availability of a universal influenza vaccination program in the United States and Canada, seasonal influenza vaccine (SIV) uptake among the elderly remains suboptimal. Understanding the factors that determine SIV uptake in this important population subgroup is essential for designing effective interventions to improve seasonal influenza vaccination among the elderly. We evaluated the determinants of SIV uptake in the elderly in the United States and Canada. Methods: We systematically searched relevant bibliographic databases and websites from 2000 to 2017 for population-based clinical trials or observational studies conducted in community-based elderly individuals in the United States or Canada, irrespective of health status. Two reviewers independently screened the identified citations for eligibility using a two-stage sifting approach to review the title/abstract and full-text article. We gathered data on determinants of uptake (any vaccine receipt) and adherence (receipt of vaccine in more than one season) to seasonal influenza vaccination. Where possible, we pooled the data using inverse variance methods to minimize the variance of the weighted average. Results: Five cross-sectional studies on SIV uptake (none on adherence) from the United States met our eligibility criteria. Being older (pooled odds ratio [POR] = 1.44, 95% Confidence Interval [CI] = 1.11, 1.86); White (POR = 1.33, 95% CI = [1.10, 1.64]); and having higher income (POR = 1.06, 95% CI = [1.04, 1.09]); and health insurance (POR = 1.40, 95% CI = [1.25, 1.55]) were associated with increased SIV uptake. Conclusion: Older, ethnically White, higher income elderly individuals with access to health insurance coverage and a regular health care provider have higher SIV uptake in the United States. There was limited evidence for other socioeconomic and health-related determinants. Further studies are needed to provide an evidence base for planning more effective influenza vaccination programs in the United States.

Epidemics of seasonal influenza viruses cause considerable morbidity and mortality each year. Various types and subtypes of influenza circulate in humans and evolve continuously such that individuals at risk of serious complications need to be vaccinated annually to keep protection up to date with circulating viruses. The influenza vaccine in most parts of the world is a trivalent vaccine, including an antigenically representative virus of recently circulating influenza A/H3N2, A/H1N1, and influenza B viruses. However, since the 1970s influenza B has split into two antigenically distinct lineages, only one of which is represented in the annual trivalent vaccine at any time. We describe a lineage selection strategy that optimizes protection against influenza B using the standard trivalent vaccine as a potentially cost effective alternative to quadrivalent vaccines. ; Sera used in this research were kindly provided by the following collaborators: for Australia by Dr. Ian Barr, WHO Collaborating Center, Melbourne, Australia, pediatric sera for the United States by Dr. Jackie Katz, WHO Collaborating Center, Atlanta, US, for Japan by Dr. Takato Odagiri, WHO Collaborating Center, Tokyo, Japan, for China by Dr. Yuelong Shu, WHO Collaborating Center, Beijing, China, for the United Kingdom by Dr. John Wood, NIBSC, Hertfordshire, UK. Additional thanks to Drs Nancy Cox, Michael Shaw, and Alexander Klimov. This work was supported by European Union FP7 program EMPERIE (22349). JMF is supported by a Fellowship in Biomedical Informatics from the Medical Research Council (UK) and a Junior Research Fellowship from Homerton College, Cambridge. Funded by: ERCPMC grant number: FP7 22349. ; This is the final version of the article. It first appeared from Elsevier via https://doi.org/10.1016/j.vaccine.2016.01.042

BACKGROUND: Despite nearly universal influenza vaccination for active duty military personnel, breakthrough influenza infections occur. We are reporting on the second year of the Pragmatic Assessment of Influenza Vaccine Effectiveness in the DoD (PAIVED), comparing three FDA-licensed influenza vaccine types (egg-based, cell -based, and recombinant) to assess differences in immunogenicity and effectiveness. METHODS: Participants in the second year of PAIVED were enrolled from Oct 2019 through Jan 2020 at 9 military facilities. Participants received weekly inquiries about influenza-like-illnesses (ILI) experienced in the past week, and if the participant reported having a cough or sore throat and a) muscle/body aches or fatigue and/or b) being feverish or having chills, they were scheduled for a clinic visit. During this visit, a blood sample and a nasal swab were collected, as well as information about symptom duration and severity. A second (convalescent) visit was conducted approximately 4 weeks later, which involved collecting additional information about the duration of symptoms and illness burden, as well as a second blood draw. Due to the COVID-19 pandemic, acute and convalescent visits were disrupted at most sites in March and April due to COVID-19 precautions. RESULTS: PAIVED year 2 enrolled 5,892 participants who completed demographic forms (Table 1). Among those who reported any ILIs, most reported one ILI (1,345), while 264 reported two ILIs, and 42 reported three ILIs. Nasal swabs were processed from 273 ILIs at four sites (Fig 1), and 14 cases of influenza were identified thus far. The median duration of ILIs was ten days, with a median of three days of limited activity, and two days with fever. Nine individuals were hospitalized. Table 1. Demographic characteristics of individuals enrolled in PAIVED 2019/20 [Image: see text] Figure 1. Lab results as of 5/15 (N=273 samples) [Image: see text] CONCLUSION: Over 25% of participants reported an ILI, and 5% of the nasal swabs that have been tested thus far ...

BACKGROUND: In Hong Kong, people aged 50-64 years were added as a recommended priority group (recommended group) for influenza vaccination by the Department of Health (DH) starting from 2011/12 onwards. The coverage rate of influenza vaccination for this age group was suboptimal at 8.5 % in 2012/13. This study investigates the factors associated with the uptake of influenza vaccination among adults in Hong Kong aged 50-64 years. METHODS: A case-control study was conducted in communities by street intercept interviews from 17 July to 15 August 2013. Cases were adults aged 50-64 years who had received the influenza vaccine in 2011/12 or 2012/13, while controls were the same as the cases, except they had not received the influenza vaccine in 2011/12 or 2012/13. Multiple logistic regression analysis was performed on the data to explore the associations between vaccination status and the variables. RESULTS: Six hundred and four respondents in total were interviewed and included in the analysis. There were 193 cases (vaccinated) and 411 controls (non-vaccinated), with a case-to-control ratio of 1:2.1. The following were strongly associated with vaccination compared to other factors: 'eligible for free government vaccine' (OR6.38, 95 % CI, 3.43-11.87, p 80 %) were willing to be vaccinated if it was free. CONCLUSIONS: Factors related to free and convenient vaccination, the perception of the severity of symptoms when contracting influenza had a comparatively strong association with influenza vaccination uptake amongst 50-64 year olds, compared to other factors.

Background: Influenza is a substantial threat to healthcare settings, and the annual influenza vaccine (IV) is an effective preventive measure against influenza. However, the vaccination rate among health care workers (HCWs) remains low. Objective: This study aimed at assessing vaccine coverage among HCWs at the primary health care centers of the Saudi Ministry of Health (MOH), and determine factors affecting compliance to vaccination. Methods: We conducted a cross-sectional study, and by applying a multistage clustering sample method, we randomly selected 83 male and 202 female HCWs. We used a self-administered questionnaire to collect information about IV uptake and its determinants. We performed the chi-square test to define associated factors and used binomial logistic regression analysis to determine the unconfounded predictors of IV. Results: The rate of IV among HCWs ranged from 53.3% during 2016 to 51.7% during the 2018 season. Compliances to successive vaccination over the past three years were only 30.2%; however, 66.2% of HCWs intended to receive the vaccine during the upcoming season. The main reasons for IV uptake included self-protection against influenza (60.7%) and caring about client's patients (44.8%). Single female nurses were more likely to be immunized against IV than other HCWs p<0.05. Both reading the official MOH IV guidelines and feeling of having sufficient knowledge about IV were unconfounded predictors for the vaccine. Conclusion: The overall immunization coverage was suboptimal, and the fact that reading the official MOH IV guidelines had a strong statistical association with a positive attitude towards vaccination emphasizes the role of governmental authorities in enhancing vaccine among the HCWs.

Influenza vaccine effect on the occurrence and severity of influenza virus infection in a population residing in nursing homes for the elderly was studied as a cohort study during an influenza A (H3N2) epidemic in Japan. Of 22,462 individuals living in 301 welfare nursing homes, 10,739 voluntarily received inactivated, sub-unit trivalent influenza vaccine in a programme supported by the Osaka Prefectural Government. There were statistically significantly fewer cases of influenza, hospital admissions due to severe infection, and deaths due to influenza in the vaccinated cohort compared to the unvaccinated controls. No serious adverse reactions to vaccination were recorded. Thus influenza vaccination is effective for preventing influenza disease in persons aged 65 years and over, and should be an integral part of the care of this population residing in nursing homes.

Previous studies have shown that seasonal influenza strikes annually causing millions to fall sick and several hundred thousand to die globally. Hence, universal vaccination is a public health aim to control influenza. The Hong Kong Government started to introduce the School Outreach Vaccination (SOV) program in 2018 to increase vaccination rates in children. This study looked at the impact this had on hospital admissions and estimated vaccination rates in the total population, using a questionnaire-based tool. The SOV program significantly increased vaccination coverage rates with a 1% increase associated with a reduction of 4.3 influenza-related hospital admissions of school-aged children. The estimation of vaccine coverage rates among the under 5-year olds (48.5%), primary school children (69.3%) and over 65-year olds (45.7%), through the questionnaire-based tool, was within the 95% confidence interval of the coverage rates published by the Center for Health Protection of the Hong Kong Government, 47.4%, 68.1% and 45.8%, respectively. Extension of the SOV program should be considered in secondary schools to increase the coverage rates in adolescents. The questionnaire survey may inform government how to achieve universal vaccination for specific age groups.

In February 2009, Nobilon granted the World Health Organization (WHO) a non-exclusive licence to develop, register, manufacture, use and sell seasonal a pandemic live attenuated influenza vaccine (LAIV) produced on embryonated chicken eggs. WHO was permitted to grant sub-licences to vaccine manufacturers in developing countries within the framework of its influenza vaccine technology transfer initiative. In parallel, the Institute of Experimental Medicine (IEM), Russia, concluded an agreement with WHO for the supply of Russian LAIV reassortants for use by these manufacturers. Also in 2009, IEM carried out a study on a novel A/17/California/2009/38 (H1N1) pandemic LAIV candidate derived from the pandemic-related A/California/07/2009 (H1N1) influenza virus and the attenuated A/Leningrad/134/17/57 (H2N2) master donor virus, using routine reassortant technique in embryonated chicken eggs. Following successful preclinical studies in eggs and in ferrets, a double-blind, controlled, randomized clinical trial was carried out in immunologically naïve study participants between 12–18 and 18–60 years old. Collectively, the immunogenicity data (haemagglutinin inhibition test, ELISA and cytokine tests for the detection of memory T cells) support the use of a single dose of the pandemic H1N1 LAIV in 12–60 year olds. The outcome of the studies showed no significant adverse reactions attributable to the vaccine, and suggests that the vaccine is as safe and immunogenic as seasonal influenza vaccines. Importantly, it was clearly demonstrated that reliance on the HAI assay alone is not recommended for testing LAIV. To date, via the licence agreement with WHO, the H1N1 LAIV has been transferred to the Government Pharmaceutical Organization in Thailand, the Serum Institute of India, and the Zhejiang Tianyuan Bio-Pharmaceutical Co., Ltd. in China.

BACKGROUND: Healthcare workers (HCWs) are at heightened risk of exposure to respiratory pathogens. There are limited published data on influenza-like illness (ILI) experience among HCWs, and the few available studies were hampered by incomplete vaccination histories. PAIVED, a multicenter, multiservice study assessing influenza vaccine effectiveness in the Department of Defense, provides a unique opportunity to describe ILI experience among vaccinated HCWs compared to vaccinated non-HCWs. METHODS: PAIVED participants were randomized to receive either egg-based, cell-based, or recombinant-derived influenza vaccine then surveyed weekly for ILI. At enrollment, participants provided key demographic data including whether they were HCWs with direct patient contact. ILI was defined a priori as 1) having cough or sore throat plus 2) feeling feverish/having chills or having body aches/fatigue. Participants with ILI completed a daily symptom diary for seven days and submitted a nasal swab for pathogen detection. RESULTS: Of 4433 eligible participants enrolled during the 2019-20 influenza season, 1551 (35%) were HCWs. A higher percentage of HCWs experienced an ILI than non-HCWs (34% vs 26%, p< 0.001). Overall, HCWs were more likely to be female (42% vs 32%), age 25-34 years (39% vs 28%), active-duty military (81% vs 62%), non-smokers (88% vs 75%), and physically active (92% vs 85%). Self-reported race differed between HCWs and non-HCWs; a higher proportion of HCWs identified as White (63% vs 56%) or Asian (8% vs 5%). Similar demographic differences existed among HCWs and non-HCWs with ILI. HCWs were more likely to respond to at least 50% of weekly surveillance messages, irrespective of ILI status. HCWs with ILI had less severe lower respiratory symptoms (p< 0.001) and a shorter duration of illness (12.4±8.1 days vs 13.7±9.0, p=0.005) than non-HCWs. Pathogen data is pending. CONCLUSION: HCWs in PAIVED were more likely to report ILI than their non-HCW counterparts yet tended to have lower illness severity, possibly ...

Abstract Background Although there is rapid progress in vaccine research regarding influenza pandemic vaccines it is expected that pandemic influenza vaccine production can only start once the pandemic virus has been recognized. Therefore, pandemic vaccine capacity will be limited at least during the first phase of an influenza pandemic, requiring vaccine prioritization strategies. WHO recommends developing preliminary priorities for pandemic vaccine use. The goal of this review is to provide a thorough overview of pandemic vaccine prioritization concepts in the 27 European Union (EU) member states and the four non-EU countries of the Global Health Security Action Group. Methods Between September and December 2006 data was collected for each country through two data sources: (i) the national influenza pandemic plan; (ii) contacting key persons involved in pandemic planning by email and/or phone and/or fax Results Twenty-six (84%) countries had established at least one vaccine priority group. Most common reported vaccine priority groups were health care workers (HCW) (100%), essential service providers (ESP) (92%) and high risk individuals (HRI) (92%). Ranking of at least one vaccine priority group was done by 17 (65%) of 26 countries. Fifteen (88%) of these 17 countries including a ranking strategy, decided that HCW with close contact to influenza patients should be vaccinated first; in most countries followed and/or ranked equally by ESP and subsequently HRI. Rationales for prioritization were provided by 22 (85%) of 26 countries that established vaccine priority groups. There was large variation in the phrasing and level of detailed specification of rationales. Seven (32%) of 22 countries providing rationales clearly associated each vaccine priority group with the specific rationale. Ten (32% of the 31 countries studied) countries have consulted and involved ethical experts to guide decisions related to vaccine prioritization. Conclusion In the majority of the countries the establishment of vaccine priority groups, ranking and underlying rationales are in line with WHO recommendations. In most public plans the criteria by which prioritized groups are identified are not easily recognizable. Clarity however, may be necessary to assure public acceptability of the prioritization. Ethical experts, results of modelling exercises could play an increasing role in the future decision making process.

Members of the I-MOVE+ working group - Portugal: B. Nunes, A. Machado, A.P. Rodrigues, V. Gómez, I. Kislaya, R. Guiomar, P. Pechirra, P. Cristóvão, I. Costa (National Health Institute Doutor Ricardo Jorge, Lisbon), A.Panarra, R. Côrte-Real (Centro Hospitalar de Lisboa Central, Lisbon), J. Poças, M.J. Peres (Centro Hospitalar de Setúbal, Setúbal). ; Between September 2017 and February 2018, influenza A(H1N1)pdm09, A(H3N2) and B viruses (mainly B/Yamagata, not included in 2017/18 trivalent vaccines) co-circulated in Europe. Interim results from five European studies indicate that, in all age groups, 2017/18 influenza vaccine effectiveness was 25 to 52% against any influenza, 55 to 68% against influenza A(H1N1)pdm09, -42 to 7% against influenza A(H3N2) and 36 to 54% against influenza B. 2017/18 influenza vaccine should be promoted where influenza still circulates. ; The five studies have received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 634446 to conduct the study in individuals aged 65 years or more. ECDC has contributed to fund some study sites of the EU-PC study under the Framework contract No ECDC/2014/026 for the individuals aged less than 65 years. ; info:eu-repo/semantics/publishedVersion

AbstractOur objective was to estimate and replicate influenza vaccine effectiveness (VE)
for the 2014/2015 influenza season (IS) based on routine data from a
German health insurance claims dataset. In addition, we investigated associated
methodological aspects. From the AOK Baden-Württemberg, claims data of
2.64 million insured persons residing in Baden-Wuerttemberg and aged 15 years
and older were available for analysis. Based on influenza vaccine-specific
reimbursement codes claimed in the vaccination period of 2014, participants were
classified as either vaccinated or unvaccinated. Baseline covariates that could
confound the association between vaccination and influenza infection were
considered for all participants. Covariates included age, sex, place of
residence, and covariates indicative of health status and health-service
utilization. The primary outcome was defined as influenza hospitalization during
the IS in winter and spring of 2015. Secondary outcomes included pneumonia
hospitalizations, and all-cause mortality among others. Propensity score
matching (PSM) was used to build a comparable set of vaccinated and unvaccinated
participants. A bias analysis was conducted by estimating VE pre- and post-IS,
periods in which vaccination is not thought to be effective, because influenza
is not circulating in the population. A subset of 839,706 participants could
successfully be matched with a 1:1 ratio. The estimated influenza VE (based on
influenza hospitalization) was 27% [95% confidence interval
(CI): 17%; 36%], which compares well with the estimate of the
RKI for the same season (27% [95% CI: -1%;
47%]). Bias analysis revealed that result could be partially accounted
for by residual confounding yielding a potential overestimation of the true
underlying effect. Secondary outcomes for pneumonia hospitalizations and
mortality showed similar results though likely prone to a greater extent of
residual confounding. It can be concluded that (1) secondary data from German
health insurances can be used to derive plausible influenza VE estimates, and
(2) PSM is a useful and transparent method to derive those estimates. In
addition, (3) residual confounding is a relevant problem in observational
studies on VE and (4) bias analysis in pre- and post-season periods are an
essential complement for interpretation of results.