Do recommended high-risk adults benefit from a first influenza vaccination?

How high is a high risk? Prioritising high-risk individuals in an influenza pandemic

Pandemic contingency plans frequently define priority groups that are given preferential access to influenza vaccine. One of the most commonly named groups for prioritisation is that of high-risk individuals. However, current models of categorisation are unsatisfactory in a number of ways. It will be argued that existing vaccination strategies fail to adequately define what kind of risks are being considered and how, as well as on the basis of which information, these risks are calculated. Moreover, it will be suggested that existing vaccination strategies fail to specify of what magnitude a risk has to be, in order to be categorised as 'high'. Finally, it shall be argued that a mere focus on the size of a risk factor may lead policy makers to overlook underlying concerns of distributive justice.

Effectiveness of H1N1 vaccine for the prevention of pandemic influenza in Scotland, UK: a retrospective observational cohort study

BACKGROUND

A targeted vaccination programme for pandemic H1N1 2009 influenza was introduced in Scotland, UK, in October, 2009. We sought to assess the effectiveness of this vaccine in a sample of the Scottish population during the 2009-10 pandemic.

METHODS

We assessed the effectiveness of the Scottish pandemic H1N1 2009 influenza vaccination with a retrospective cohort design. We linked data of patient-level primary care, hospital records, death certification, and virological swabs to construct our cohort. We estimated vaccine effectiveness in a nationally representative sample of the Scottish population by establishing the risk of hospital admission and death (adjusted for potential confounders) resulting from influenza-related morbidity in vaccinated and unvaccinated patients and laboratory-confirmed cases of influenza H1N1 2009 in a subset of patients.

FINDINGS

Pandemic H1N1 2009 influenza vaccination began in week 43 of 2009 (Oct 21, 2009) and was given to 38,296 (15·5%, 95% CI 15·4-15·6) of 247,178 people by the end of the study period (Jan 31, 2010). 208,882 (85%) people were unvaccinated. There were 5207 emergency hospital admissions and 579 deaths in the unvaccinated population and 924 hospital admissions and 71 deaths in the vaccinated population during 23,893,359 person-days of observation. The effectiveness of H1N1 vaccination for prevention of emergency hospital admissions from influenza-related disorders was 19·5% (95% CI 0·8-34·7). The vaccine's effectiveness in preventing laboratory-confirmed influenza was 77·0% (95% CI 2·0-95·0).

INTERPRETATION

Pandemic H1N1 2009 influenza vaccination was associated with protection against pandemic influenza and a reduction in hospital admissions from influenza-related disorders in Scotland during the 2009-10 pandemic.

FUNDING

National Institute for Health Research Health Technology Assessment Programme (UK).

Seasonal Influenza Vaccine Effectiveness in the community (SIVE): protocol for a cohort study exploiting a unique national linked data set

INTRODUCTION

Seasonal influenza vaccination is recommended for all individuals aged 65 years and over and in individuals younger than 65 years with comorbidities. There is good evidence of vaccine effectiveness (VE) in young healthy individuals but less robust evidence for effectiveness in the populations targeted for influenza vaccination. Undertaking a randomised controlled trial to assess VE is now impractical due to the presence of national vaccination programmes. Quasi-experimental designs offer the potential to advance the evidence base in such scenarios, and the authors have therefore been commissioned to undertake a naturalistic national evaluation of seasonal influenza VE by using data derived from linkage of a number of Scottish health databases. The aim of this study is to examine the effectiveness of the seasonal influenza vaccination in the Scottish population.

METHODS AND ANALYSIS

A cohort study design will be used pooling data over nine seasons. A primary care database covering 4% of the Scottish population for the period 2000-2009 has been linked to the national database of hospital admissions and the death register and is being linked to the Health Protection Scotland virology database. The primary outcome is VE measured in terms of rate of hospital admissions due to respiratory illness. Multivariable regression will be used to produce estimates of VE adjusted for confounders. The major challenge of this approach is addressing the strong effect of confounding due to vaccinated individuals being systematically different from unvaccinated individuals. Analyses using propensity scores and instrumental variables will be undertaken, and the effect of an unknown confounder will be modelled in a sensitivity analysis to assess the robustness of the estimates.

ETHICS AND DISSEMINATION

The West of Scotland Research Ethics Committee has classified this project as surveillance. The study findings will be disseminated in peer-reviewed publications and presented at international conferences.

Receipt of influenza and pneumonia vaccinations: the dual disparity of rural minorities

OBJECTIVES

To examine the receipt of age-appropriate influenza and pneumococcal polysaccharide vaccinations (PPV), with particular attention to rural minority persons.

DESIGN

Data were drawn from the 2005 Behavioral Risk Factor Surveillance System. The dependent variables were self-reported receipt of annual influenza immunizations in adults aged 50 and older (n=177,417) or lifetime pneumococcal immunizations in adults aged 65 and older (n=81,762). The main independent variables were residence and race.

MEASUREMENTS

All data are self-reported. Multivariate analysis controlled for selected personal and county-level characteristics. Analyses were conducted in 2009/10.

RESULTS

Forty-two percent of adults aged 50 and older reported an influenza vaccination; 31.1% of rural African Americans reported an influenza vaccination, and 64.6% reported a PPV. White and African-American rural residents reported lower vaccination rates. Adjusted analysis indicated an interaction between race and rurality. White rural residents were more likely to be vaccinated than other whites, whereas rural African Americans were less likely to be vaccinated than urban African Americans.

CONCLUSION

This study confirms previous findings while finding an interactive effect between rurality and race. The results indicated the importance of provider availability to delivery. Alternative delivery methods may be an effective solution to improve delivery rates.

Prognosis of primary care patients aged 80 years and older with lower respiratory tract infection

BACKGROUND

Predictors for a complicated course of a lower respiratory tract infection (LRTI) episode among patients aged > or =80 years are unknown.

AIM

To determine prognostic factors for hospital admission or death within 30 days after first onset of LRTI among primary care patients aged > or =80 years.

DESIGN OF STUDY

Retrospective cohort study.

SETTING

Utrecht General Practitioner Research Network.

METHOD

Data were obtained using the computerised database of the research network over the years 1997 to 2003. Multivariable logistic regression analysis was applied to estimate the independent association of predictors with 30-day hospitalisation or death.

RESULTS

In all, 860 episodes of LRTI were observed in 509 patients; 13% of patients were hospitalised or died within 30 days. Type of LRTI, diabetes, use of oral glucocorticoids, use of antibiotics in the previous month, and hospitalisation in the previous 12 months were independently associated with the combined outcome. Patients with insulin-dependent diabetes mellitus had a greater risk of 30-day hospitalisation or death compared with patients with non-insulin-dependent diabetes.

CONCLUSION

Independent of age, serious comorbidity - notably the presence of insulin-dependent diabetes or exacerbation of chronic obstructive pulmonary disease requiring oral glucocorticoids - increases the risk for complications, including hospital admissions, in patients aged > or =80 years with an LRTI.

A comparison of populations vaccinated in a public service and in a private hospital setting in the same area

Background

Improving immunisation rates in risk groups is one of the main objectives in vaccination strategies. However, achieving high vaccination rates in children with chronic conditions is difficult. Different types of vaccine providers may differently attract high risk children.

Aim

To describe the characteristics of two populations of children who attended a private and a public immunisation provider in the same area. Secondarily, to determine if prevalence of patients with underlying diseases by type of provider differs and to study if the choice of different providers influences timeliness in immunisation.

Methods

We performed a cross-sectional study on parents of children 2 – 36 months of age who attended a private hospital immunisation service or a public immunisation office serving the same metropolitan area of Rome, Italy. Data on personal characteristics and immunisation history were collected through a face to face interview with parents of vaccinees, and compared by type of provider. Prevalence of underlying conditions was compared in the two populations. Timeliness in immunisation and its determinants were analysed through a logistic regression model.

Results

A total of 202 parents of children 2–36 months of age were interviewed; 104 were in the public office, and 98 in the hospital practice. Children immunised in the hospital were more frequently firstborn female children, breast fed for a longer period, with a lower birthweight, and more frequently with a previous hospitalisation. The prevalence of high risk children immunised in the hospital was 9.2 vs 0% in the public service (P = 0.001). Immunisation delay for due vaccines was higher in the hospital practice than in the public service (DTP, polio, HBV, and Hib: 39.8% vs 22.1%; P = 0.005). Anyway multivariate analyses did not reveal differences in timeliness between the public and private hospital settings.

Conclusion

Children with underlying diseases or a low birthweight were more frequently immunised in the hospital. This finding suggests that offering immunisations in a hospital setting may facilitate vaccination uptake in high risk groups. An integration between public and hospital practices and an effort to improve communication on vaccines to parents, may significantly increase immunisation rates in high risk groups and in the general population, and prevent immunisation delays.