Predictors of IV behaviors during and after the 2009 influenza pandemic in France

Background

Controversies about the 2009 H1N1 pandemic influenza vaccination might have impacted the motivational processes that underlie individual immunization against seasonal influenza. The purpose of this article is to investigate correlates of vaccine uptake during and after the pandemic.

Methods

Data from the 1174 subjects of the CoPanFlu France cohort aged 15 and over were used. We used logistic regression models to identify social and behavioral predictors of getting vaccinated against seasonal influenza in 2009–2010 and in 2010–2011 and against H1N1 influenza in 2009–2010.

Results

This study points out that correlates of vaccination behaviors varied according to the vaccine. Respondents under 65 years who adopted the seasonal influenza vaccine were, as usual, more likely to belong to a target group and have a lower education, contrary to subjects who chose the pandemic vaccine. Exceptionally during the pandemic, a higher socioeconomic status also led to adoption of either vaccine. Motivational processes differed by vaccine. Uptaking the “new” pandemic vaccine was the result of a deliberative decision-making process, influenced by cognitive factors related to the pandemic context (such as perceived severity of the H1N1 flu strain and trust in public health authorities). In contrast, respondents got the seasonal flu vaccine without relying on explicit justifications, but instead through habit of performing this behavior in the past.

Conclusions

Target groups for seasonal influenza but not those for pandemic influenza were more likely to adopt the pandemic vaccine, which is a cause for great concern. This may be due to large extent to the automatic and habitual nature of influenza vaccination decisions. Public health authorities, should pay more attention to situational than informational cues to facilitate vaccine uptake among priority groups, especially in case of mild pandemic influenza.     

Determinants of uptake of influenza vaccination among pregnant women – A systematic review

Background

Pregnant women have the highest priority for seasonal influenza vaccine. However, suboptimal coverage has been repeatedly noted in this population. To improve vaccine uptake, reviewing the determinants of vaccination is of increasing importance.

Methods

A detailed literature search was performed up to November 30, 2013 to retrieve articles related to uptake of influenza vaccination during pregnancy.

Results

Forty-five research papers were included in the review. Twenty-one studies assessed the coverage of seasonal influenza vaccination, 13 studies assessed coverage of A/H1N1 pandemic vaccination and 11 studies assessed both. Vaccination uptake ranged from 1.7% to 88.4% for seasonal influenza, and from 6.2% to 85.7% for A/H1N1 pandemic influenza. Many pregnant women were unaware that they were at high risk for influenza and its complications during pregnancy. They were also more likely to underestimate the threat of influenza to themselves and their fetus. Moreover, they had substantial concerns about the safety and efficacy of the influenza vaccine during pregnancy. Negative media reports contributed to the perception that influenza vaccination during pregnancy was risky and could result in adverse pregnancy outcomes. Although health care providers’ (HCPs) recommendations were consistently associated with vaccine uptake, most did not recommend the vaccine to their pregnant clients.

Conclusions

Influenza vaccination uptake among pregnant women is suboptimal and HCPs rarely recommend it. Positive vaccination recommendations from HCPs as well as direct access to the vaccine would likely substantially improve vaccination acceptance.     

The impact of pandemic A(H1N1)pdm09 influenza and vaccine-associated adverse events on parental attitudes and influenza vaccine uptake in young children

Introduction

Parental attitudes towards vaccination significantly influence vaccine uptake. The A(H1N1)pdm09 influenza pandemic was followed in 2010 by an unprecedented increase in febrile reactions in children receiving trivalent inactivated influenza vaccine manufactured by bioCSL. Uptake of TIV in children <5 years in Western Australia (WA) decreased in 2010 and has remained low. The impact of pandemic A(H1N1)pdm09 and adverse-events on parental attitudes towards vaccination is uncertain.

Materials and Methods

A parental attitudes survey towards influenza illness and vaccination was conducted as part of the West Australian Influenza Vaccine Effectiveness study. Vaccination status was assessed by parental interview and confirmed by the national register and/or vaccine providers. Parental attitudes from vaccinated and unvaccinated children and attitudes in 2008–2009 and 2010–2012 were compared. Principal Component Analysis was conducted to determine core attitudes that influenced vaccine uptake.

Results

Vaccination history and parental attitude surveys were available from 2576 children. Parents of fully vaccinated children less frequently stated that influenza was a mild disease, more frequently stated that influenza vaccine was safe and were less frequently worried about vaccine side effects.Uptake of influenza vaccine decreased significantly from 2010 onwards. From 2010, parents were less concerned about severe influenza, but more concerned about vaccine side effects and safety. Despite this significant shift in attitudes towards influenza vaccine, parental acceptance of vaccines on the national immunisation program did not change. Principal Component Analysis revealed that attitudes around vaccine safety and efficacy were the most important attitudes impacting on vaccine uptake.

Conclusions

Parental attitudes to influenza vaccine changed from 2010. Confidence in the WA preschool influenza vaccination program remains low yet appeared unchanged for other vaccines. Restoring public confidence in childhood influenza vaccination is needed before uptake can be improved.     

Factors influencing pandemic influenza vaccination of healthcare workers--a systematic review

Introduction

Maintaining the health and availability of Health care workers (HCW) is an essential component of pandemic preparedness. A key to protecting HCW during the H1N1 pandemic was influenza vaccination. Numerous researchers have reported on factors influencing H1N1 vaccination behaviour in various HCW groups. This systematic review aims to inform future influenza vaccine interventions and pandemic planning processes via the examination of literature in HCW H1N1 vaccination, in order to identify factors that are (1) unique to pandemic influenza vaccination and (2) similar to seasonal influenza vaccination research.

Methods

We conducted a comprehensive review of literature (MEDLINE, PubMed, EMBASE, PsycINFO, CINHAL, AMED, Cochrane Library, ProQuest, and grey literature sources) published between January 2005 and December 2011 to identify studies relevant to HCW pH1N1 vaccine uptake/refusal.

Results

20 publications sampling HCW from different geographic regions are included in this review. H1N1 vaccine coverage was found to be variable (9–92%) across HCW populations, and self-reported vaccine status was the most frequently utilized predictor of pandemic vaccination. HCW were likely to accept the H1N1 vaccine if they perceived, (1) the H1N1 vaccine to be safe, (2) H1N1 vaccination to be effective in preventing infection to self and others (i.e. loved ones, co-workers and patients), and (3) H1N1 was a serious and severe infection. Positive cues to action, such as the access of scientific literature, trust in public health communications and messaging, and encouragement from loved ones, physicians and co-workers were also found to influence HCW H1N1 uptake. Previous seasonal influenza vaccination was found to be an important socio-demographic predictor of vaccine uptake. Factors unique to HCW pandemic vaccine behaviour are (1) lack of time and vaccine access related barriers to vaccination, (2) perceptions of novel and rapid pandemic vaccine formulation, and (3) the strong role of mass media on vaccine uptake.

Conclusions

Many of the factors that influenced HCW pandemic vaccination decisions have previously been reported in seasonal influenza vaccination literature, but some factors were unique to pandemic vaccination. Future influenza vaccine campaigns should emphasize the benefits of vaccination and highlight positive cues to vaccination, while addressing barriers to vaccine uptake in order to improve vaccine coverage among HCW populations. Since pandemic vaccination factors tend be similar among different HCW groups, successful pandemic vaccination strategies may be effective across numerous HCW populations in pandemic scenarios.     

Health and economic impact of the seasonal influenza vaccination programme in England

Background

The seasonal influenza vaccination programme in England targets individuals over 65 years old and in clinical risk groups.

Methods

A model of influenza transmission and disease was fitted to weekly primary care consultations due to influenza in a typical pre-pandemic season (2006/2007). Different scenarios were constructed about influenza severity and how well vaccines match circulating strains to assess the impact and cost-effectiveness of the current vaccination programme.

Results

A well-matched vaccine may reduce the incidence of laboratory-confirmed influenza illness from 8.2% (95% range 4.3–13%) to 5.9% (95% range 2.9–9.7%), with 56–73% of this due to indirect protection. The programme is likely to be cost-effective unless both low severity and poor matching is assumed.

Conclusion

The current seasonal influenza vaccination programme appears to substantially reduce disease burden and provides good value for money.     

Influenza pandemic (H1N1) 2009 activity during summer 2009. Effectiveness of the 2008-9 trivalent vaccine against pandemic influenza in Spain

Introduction

The Spanish influenza surveillance system (SISS) maintained its activity during the summer of 2009 to monitor the influenza pandemic.

Objectives

To describe pandemic influenza activity from May to September 2009 and to estimate the effectiveness of the 2008-9 seasonal influenza vaccine against laboratory-confirmed pandemic (H1N1) 2009 influenza.

Methods

Data from the SISS were used to identify the trend of pandemic (H1N1) 2009 influenza outside the influenza season. For the effectiveness study, we compared the vaccination status of notified cases [influenza-like illnesses (ILI) laboratory confirmed as pandemic influenza] with that of the test-negative controls.

Results

The first laboratory-confirmed case of the pandemic virus was notified in the system in week 20/2009. The ILI rate increased gradually in the study period, exceeding basic activity in week 38. The proportion of pandemic (H1N1) 2009 influenza viruses detected by the system represented 14% in week 20/2009 and rapidly increased to 90% in week 34. The adjusted vaccine effectiveness of the 2008-9 seasonal vaccine against laboratory-confirmed pandemic influenza was 12% (-30; 41).

Conclusions

The SISS became an essential tool for pandemic monitoring in Spain. The improved SISS will provide more accurate information on influenza activity in future seasonal or pandemic waves. Using surveillance data, we could not demonstrate the effectiveness of the seasonal 2008-9 vaccine against laboratory-confirmed pandemic influenza.     

Intradermal and virosomal influenza vaccines for preventing influenza hospitalization in the elderly during the 2011–2012 influenza season: A comparative effectiveness study using the Valencia health care information system

Background

The use of intradermal vaccination or virosomal vaccines could increase protection against influenza among the vulnerable population of older adults. Studies assessing the comparative effectiveness of these two influenza vaccine types in this age group are lacking.

Methods

We conducted a retrospective cohort study to estimate the comparative effectiveness of intradermal seasonal trivalent-influenza vaccine (TIV) delivered by a microneedle injection system and a virosomal-TIV intramuscularly delivered for prevention of influenza hospitalization in non-institutionalized adults aged ≥65 years. We obtained administrative data on immunization status and influenza hospitalization for the 2011–2012 influenza season, and used Cox regression models to assess comparative effectiveness. We estimated crude and adjusted (age, sex, comorbidity, pharmaceutical claims, recent pneumococcal vaccination and number of hospitalizations for all causes other than influenza between the previous and current influenza seasons) hazard ratios (HR).

Results

Overall, 164,021 vaccinated subjects were evaluated. There were 127 hospitalizations for influenza among 62,058 subjects, contributing 914,740 person-weeks at risk in the virosomal-TIV group, and 133 hospitalizations for influenza among 101,963 subjects, contributing 1,504,570 person-weeks at risk in the intradermal-TIV group. The crude HR of intradermal-TIV relative to virosomal-TIV was 0.64 (95% confidence interval (CI): 0.50–0.81), and the adjusted Cox estimated HR was 0.67 (95% CI: 0.52–0.85).

Conclusions

During the 2011–2012 influenza season the risk of hospitalization for influenza was reduced by 33% in non-institutionalized elderly adults who were vaccinated with intradermal-TIV compared with virosomal-TIV.     

Vaccination of adults 65 years of age and older with tetanus toxoid, reduced diphtheria toxoid and acellular pertussis vaccine (Boostrix(®)): results of two randomized trials

Background

Pertussis can cause significant morbidity in elderly patients, who can also transmit this disease to infants and young children. There is little data available on the use of acellular pertussis vaccines in recipients ≥65 years of age.

Methods

Two studies examined the safety and immunogenicity of tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis (Tdap) vaccine (Boostrix^®) in healthy ≥65 year olds. In Study A subjects received single doses of Tdap and seasonal influenza vaccine either co-administered or given one month apart. In Study B subjects received either Tdap or tetanus-diphtheria (Td) vaccine. Antibodies were measured before and one month after vaccination. Reactogenicity and safety were actively assessed using diary cards.

Results

A total of 1104 subjects 65 years of age and older received a Tdap vaccination in the two studies. In study A, no differences in immune responses to Tdap or influenza vaccine were observed between co-administered or sequentially administered vaccines. In study B, Tdap was non-inferior to Td with respect to diphtheria and tetanus seroprotection, and anti-pertussis GMCs were non-inferior to those observed in infants following a 3-dose diphtheria, tetanus and acellular pertussis (DTaP) primary vaccination series, in whom efficacy against pertussis was demonstrated. Reports of adverse events were similar between Tdap and Td groups.

Conclusions

Tdap was found to be immunogenic in subjects ≥65 years, with a safety profile comparable to US-licensed Td vaccine. Tdap and influenza vaccine may be co-administered without compromise of either the reactogenicity or immunogenicity profiles of the two vaccines.     

Non-adjuvanted 2009 influenza A (H1N1)v vaccine in pregnant women: the results of a French prospective descriptive study

In 2009, during the influenza A (H1N1)v pandemic, the French Health authorities recommended influenza immunisation for pregnant women because of the higher risk of serious influenza outcomes in that population. Thus, the non-adjuvanted inactivated influenza vaccine Panenza^® was administered to French women from the second trimester of pregnancy. Several studies suggest that inactivated seasonal influenza vaccines are safe during pregnancy but there are few data about the effects of new A (H1N1)vaccines (new antigen) on pregnant women.

Objective

The aim of the present prospective study was to describe pregnancy outcomes among women vaccinated with non-adjuvanted influenza vaccines in South Western France.

Methods

the study ran from November 2009 to February 2010 and included, on a voluntary basis, pregnant women who were vaccinated against A (H1N1) influenza in vaccination clinics or maternity wards.

Results

569 pregnant women were monitored until delivery. Compared with the general population, the risks of maternal conditions, malformations and neonatal conditions were not statistically different.

Conclusion

This study does not reveal any sign of safety concerns regarding the effects of the vaccine on pregnancy outcomes.     

How influenza vaccination policy may affect vaccine logistics

Background

When policymakers make decision about the target populations and timing of influenza vaccination, they may not consider the impact on the vaccine supply chains, which may in turn affect vaccine availability.

Purpose

Our goal is to explore the effects on the Thailand vaccine supply chain of introducing influenza vaccines and varying the target populations and immunization time-frames.

Methods

We Utilized our custom-designed software HERMES (Highly Extensible Resource for Modeling Supply Chains), we developed a detailed, computational discrete-event simulation model of the Thailand's National Immunization Program (NIP) supply chain in Trang Province, Thailand. A suite of experiments simulated introducing influenza vaccines for different target populations and over different time-frames prior to and during the annual influenza season.

Results

Introducing influenza vaccines creates bottlenecks that reduce the availability of both influenza vaccines as well as the other NIP vaccines, with provincial to district transport capacity being the primary constraint. Even covering only 25% of the Advisory Committee on Immunization Practice-recommended population while administering the vaccine over six months hinders overall vaccine availability so that only 62% of arriving patients can receive vaccines. Increasing the target population from 25% to 100% progressively worsens these bottlenecks, while increasing influenza vaccination time-frame from 1 to 6 months decreases these bottlenecks.

Conclusion

Since the choice of target populations for influenza vaccination and the time-frame to deliver this vaccine can substantially affect the flow of all vaccines, policy-makers may want to consider supply chain effects when choosing target populations for a vaccine.     

Inactivated trivalent seasonal influenza vaccine induces limited cross-reactive neutralizing antibody responses against 2009 pandemic and 1934 PR8 H1N1 strains

Background

In June 2009, we conducted a prospective study in Singapore on 51 individuals to determine their serologic responses before and following receipt of the 2009 Southern Hemisphere seasonal influenza vaccine.

Materials and methods

Paired serum samples were obtained before and 3–4 weeks after vaccination. Virus microneutralization assays were performed to quantify antibodies against A/Brisbane/59/2007 vaccine, pandemic H1N1-2009 and A/Puerto Rico/08/34 H1N1 strains.

Results

Post-vaccination, 43%, 12% and 24% of subjects displayed a 4-fold or greater rise in neutralizing antibody titers against the three strains, respectively. There was a positive correlation among individuals who showed increased titers to both pandemic H1N1-2009 and A/Puerto Rico/08/34 (p < 0.001). However, this correlation was not observed for A/Brisbane/59/2007 with either strain. The relative conservation and accessibility of predicted B-cell epitopes may explain the limited cross-reactivity of the antibodies directed against common H1N1 epitopes.

Conclusions

These results suggest that seasonal influenza vaccination confers a certain degree of cross-protection to other H1N1 strains. The correlation in cross-reactive antibody titers to A/Puerto Rico/08/34 and pandemic H1N1-2009 implies that previous exposure to pre-1957 H1N1 strains may confer some protection against the 2009 pandemic strain.     

The determinants of 2009 pandemic A/H1N1 influenza vaccination: a systematic review

Background

Pandemic A/H1N1 influenza vaccine coverage varied widely across countries. To understand the factors influencing pandemic influenza vaccination and to guide the development of successful vaccination programs for future influenza pandemics, we identified and summarized studies examining the determinants of vaccination during the 2009 influenza pandemic.

Methods

We performed a systematic literature review using the PubMED electronic database from June 2009 to February 2011. We included studies examining an association between a possible predictive variable and actual receipt of the pandemic A/H1N1 influenza vaccine. We excluded studies examining intention or willingness to receive the vaccine.

Results

Twenty-seven studies were identified from twelve countries. Pandemic influenza vaccine coverage varied from 4.8% to 92%. Coverage varied by population sub-group, country, and assessment method used. Most studies used questionnaires to estimate vaccine coverage, however seven (26%) used a vaccination registry. Factors that positively influenced pandemic influenza vaccination were: male sex, younger age, higher education, being a doctor, being in a priority group for which vaccination was recommended, receiving a prior seasonal influenza vaccination, believing the vaccine to be safe and/or effective, and obtaining information from official medical sources.

Conclusions

Vaccine coverage during the pandemic varied widely across countries and population sub-groups. We identified some consistent determinants of this variation that can be targeted to increase vaccination during future influenza pandemics.     

Multilevel correlates for human papillomavirus vaccination of adolescent girls attending safety net clinics

Background

Adolescent HPV vaccination in minority and low income populations with high cervical cancer incidence and mortality could reduce disparities. Safety-net primary care clinics are a key delivery site for improving vaccination rates in these populations.

Purpose

To examine prevalence of HPV initiation (≥1 dose), completion (receipt of dose 3 within 12 months of initiation), and receipt of 3 doses in four safety-net clinics as well as individual-, household-, and clinic-level correlates of initiation.

Methods

We used multilevel modeling to investigate HPV initiation among 700 adolescent females who sought primary care in four safety-net clinics in Dallas, Texas from March 2007 to December 2009. Data were abstracted from patients’ paper and electronic medical records.

Results

HPV vaccine uptake varied significantly by clinic. Across clinics, initiation was 36.6% and completion was 39.7% among those who initiated. In the total study population, only 15.7% received all three doses. In multivariate, two-level logistic regression analyses, initiation was associated with receipt of other adolescent vaccines, influenza vaccination in the year prior to data abstraction, being sexually active, and having more chart documentation (presence of health maintenance questionnaire and/or immunization record). There was no association between initiation and age, race/ethnicity, or insurance status.

Conclusions

In four urban safety-net clinics, HPV initiation rates paralleled 2008 national rates. The correlation of HPV initiation with other adolescent vaccines underscores the importance of reviewing vaccination status at every health care visit. HPV vaccine uptake in safety-net clinics should continue to be monitored to understand impact on cervical cancer disparities.     

A randomised, single-blind, dose-range study to assess the immunogenicity and safety of a cell-culture-derived A/H1N1 influenza vaccine in adult and elderly populations

Background

Modern cell-culture production techniques and the use of adjuvants helps to ensure that the global demand for pandemic influenza vaccine can be met. This study aimed to assess the immunogenicty and safety profiles of various cell-culture-derived A/H1N1 pandemic vaccine formulations in healthy adult and elderly subjects.

Methods

Adult (18–60 years) subjects (n = 544) received vaccine either containing 3.75 μg of antigen with half the standard dose of MF59^® (Novartis Vaccines and Diagnostics) adjuvant, 7.5 μg antigen with a full dose of MF59, or a non-adjuvanted vaccine containing 15 μg of antigen. Elderly (≥61 years) subjects (n = 268) received either the 3.75 μg or 7.5 μg adjuvanted formulations. Two priming vaccine doses were administered 3 weeks apart, followed by a single booster dose of seasonal influenza vaccine 1 year later. Immunogenicity was assessed 3 weeks after each vaccination. The safety profile of each formulation was evaluated throughout the study.

Results

A single primary dose of each A/H1N1 vaccine formulation was sufficient to meet all three European (CHMP) licensure criteria for pandemic influenza vaccines in adult subjects. Two licensure criteria were met after one vaccine dose in elderly subjects; two primary doses were required to meet all three criteria in this age group. The highest antibody titres were observed in response to the 7.5 μg vaccine containing a full dose of MF59 adjuvant. All subjects rapidly generated seroprotective antibody titres in response to booster vaccination.

Conclusion

This study identified one 3.75 μg vaccine dose containing half the standard dose of MF59 adjuvant as optimal for adults, two doses were optimal for elderly subjects. The antigen-sparing properties of MF59, and rapid, modern, cell-culture production techniques represent significant steps towards meeting the global demand for influenza vaccine.     

Contact and communication with healthcare providers regarding influenza vaccination during the 2009-2010 H1N1 pandemic

Objective

The existence of two vaccines—seasonal and pandemic—created the potential for confusion and misinformation among consumers during the 2009-2010 vaccination season. We measured the frequency and nature of influenza vaccination communication between healthcare providers and adults for both seasonal and 2009 influenza A(H1N1) vaccination and quantified its association with uptake of the two vaccines.

Methods

We analyzed data from 4040 U.S. adult members of a nationally representative online panel surveyed between March 4th and March 24th, 2010. We estimated prevalence rates and adjusted associations between vaccine uptake and vaccination-related communication between patients and healthcare providers using bivariate probit models.

Results

64.1% (95%-CI: 61.5%-66.6%) of adults did not receive any provider-issued influenza vaccination recommendation. Adults who received a provider-issued vaccination recommendation were 14.1 (95%-CI: − 2.4 to 30.6) to 32.1 (95%-CI: 24.3-39.8) percentage points more likely to be vaccinated for influenza than adults without a provider recommendation, after adjusting for other characteristics associated with vaccination.

Conclusions

Influenza vaccination communication between healthcare providers and adults was relatively uncommon during the 2009-2010 pandemic. Increased communication could significantly enhance influenza vaccination rates.     

Correlates of 2009 H1N1 influenza vaccination among day care-aged children, Miami-Dade County

Background

The aim of this study was to assess factors influencing 2009 H1N1 influenza vaccination among a demographically diverse group of day care-aged children. Day care children were chosen because they were an initial target group for vaccination and are at higher risk of influenza infection than children cared for at home.

Methods

A cross-sectional study was conducted from March to May 2010 among parents of day care aged children in 13 day care facilities in Miami-Dade County. Data was collected by an anonymous self-administered two-page 20 question survey which consisted of demographic variables and information regarding 2009 H1N1 influenza vaccine knowledge, attitude and acceptance. Data was analyzed using SAS to conduct both bivariate and multivariate analyses.

Results

There were 773 participants in the study. The response rate ranged from 42% to 72.2% among day care centers. A total of 172 parents (22.3%) and 225 (29.1%) children had received the 2009 H1N1 influenza vaccine. Non-Hispanic White and Black parents were more likely to vaccinate their children than Hispanic and Haitian parents. Primary reasons for non-vaccination included vaccine safety (36.7%) and side effects (27.1%). Among parents who spoke with a health care professional, 274 (61.4%) stated the health care professional recommended the vaccine.

Conclusion

Misperceptions about influenza vaccination among parents created a barrier to 2009 H1N1 influenza vaccination. Parents who got the vaccine, who believed the vaccine was safe and whose children had a chronic condition were more likely to immunize their children. Clear, reliable and consistent vaccine information to the public and health care providers and initiatives targeting minority groups may increase vaccination coverage among this population.     

Acceptability of pandemic A(H1N1) influenza vaccination by Essential Community Workers in 2010 Alicante (Spain), perceived seriousness and sources of information

Objective

Describe acceptability of pandemic A(H1N1) influenza vaccination by Essential Community Workers (ECWs) from Alicante province (Spain) in January 2010. Evaluate the correlation with attitudes, beliefs, professional advice and information broadcasted by media.

Method

In this cross-sectional study, face-to-face interviews were conducted with 742 ECWs to assess their attitudes towards vaccination against the pandemic influenza strain. A multivariable regression model was made to adjust the Odds Ratios (ORs).

Results

Some ECWs reported having been vaccinated with seasonal vaccine, 21.5% (95%IC 18.6–24.9); only 15.4% (95%IC 12.8–18.4) with the pandemic one. ECWs vaccinated regularly against seasonal flu (OR 5.1; 95%IC 2.9–9.1), those who considered pandemic influenza as a severe or more serious disease than seasonal flu (OR 3.8; 95%IC 2.1–6.7) and those who never had doubts about vaccine safety (OR 3.7; 95%IC2.1–6.7) had a better acceptance of pandemic vaccine. Finally, 78.7% (95%IC 75.1–81.4) had doubts about pandemic vaccine's effectiveness.

Conclusion

The vast amount of information provided by the media did not seem to be decisive to prevent doubts or to improve the acceptability of the vaccine in ECWs. Professional advice should be the focus of interest in future influenza vaccination campaigns. These results should be taken into account by health authorities.     

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.     

Theory-based predictors of influenza vaccination among pregnant women

Background

Guidelines recommend influenza vaccination for pregnant women, but vaccine uptake in this population is far below the goal set by Healthy People 2020. The purpose of this study was to examine predictors of seasonal influenza vaccination among pregnant women.

Methods

Between 2009 and 2012, the Vaccines and Medications in Pregnancy Surveillance System (VAMPSS) conducted a prospective cohort study of influenza vaccine safety among pregnant women in the US and Canada that oversampled vaccinated women. Data for the present paper are from an additional cross-sectional telephone survey completed during the 2010–2011 influenza season. We examined predictors of influenza vaccination, focusing on Health Belief Model (HBM) constructs.

Results

We surveyed 199 pregnant women, 81% of whom had received a seasonal influenza vaccine. Vaccination was more common among women who felt more susceptible to influenza (OR = 1.82, 95% CI 1.10–3.01), who perceived greater vaccine effectiveness (OR = 3.92, 95% CI 1.48–10.43), and whose doctors recommended they have flu shots (OR = 3.06, 95% CI 1.27–7.38). Those who perceived greater barriers of influenza vaccination had lower odds of vaccination (OR = 0.19, 95% CI 0.05–0.75). Perceived social norms, anticipated inaction regret, and worry also predicted uptake, though demographic characteristics of respondents did not.

Conclusion

The HBM provides a valuable framework for exploring influenza vaccination among pregnant women. Our results suggest several potential areas of intervention to improve vaccination rates.