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.     

Correlates of seasonal flu vaccination among U.S. home health aides

Introduction

Home health aides (HAs) receive limited training and reach many older patient populations highly susceptible to influenza virus. We sought to examine socio-demographic correlates of seasonal flu vaccination receipt among HAs.

Methods

We analyzed data from the 2007 U.S. National Home Health Aide Survey, a nationally representative sample of HAs reporting on occupational status, job and demographic characteristics and receipt of seasonal flu vaccine (n = 3377).

Results

Seasonal flu vaccine receipt was low among all types of HAs (43.9%). After adjustment for socio-demographic indicators (i.e. age, gender, race and health insurance), home health, home care, hospice and personal care attendants were significantly less likely to report receiving seasonal flu vaccine as compared to licensed nursing assistants (adjusted odds ratio, AOR = 0.42, 95% CI [0.20–0.85]; 0.41, [0.17–0.99]; 0.50, [0.26–0.97], and 0.53, [0.26–0.99], respectively).

Conclusion

Targeted effective vaccination campaigns are needed to improve vaccination rates among home health aides.     

Socioecological and message framing factors influencing maternal influenza immunization among minority women

Objective

A suboptimal level of seasonal influenza vaccination among pregnant minority women is an intractable public health problem, requiring effective message resonance with this population. We evaluated the effects of randomized exposure to messages which emphasize positive outcomes of vaccination (“gain-frame”), or messages which emphasize negative outcomes of forgoing vaccination (“loss-frame”). We also assessed multilevel social and community factors that influence maternal immunization among racially and ethnically diverse populations.

Study design

Minority pregnant women in metropolitan Atlanta were enrolled in the longitudinal study and randomized to receive intervention or control messages. A postpartum questionnaire administered 30 days postpartum evaluated immunization outcomes following baseline message exposure among the study population. We evaluated key outcomes using bivariate and multivariate analyses.

Results

Neither gain- [OR = 0.5176, (95% CI: 0.203,1.322)] nor loss-framed [OR = 0.5000, 95% CI: (0.192,1.304)] messages were significantly associated with increased likelihood of immunization during pregnancy. Significant correlates of seasonal influenza immunization during pregnancy included healthcare provider recommendation [OR = 3.934, 95% CI: (1.331,11.627)], use of hospital-based practices as primary source of prenatal care [OR = 2.584, 95% CI: (1.091,6.122)], and perceived interpersonal support for influenza immunization [OR = 3.405, 95% CI: (1.412,8.212)].

Conclusion

Dissemination of vaccine education messages via healthcare providers, and cultivating support from social networks, will improve seasonal influenza immunization among pregnant minority women.     

Impact of maternal characteristics on the effect of maternal influenza vaccination on fetal outcomes

Background

Maternal infections during pregnancy have been associated with adverse fetal and infant health outcomes, and vaccination against influenza is the most effective tool to prevent morbidity and mortality due to seasonal and pandemic influenza. We evaluated the association between receipt of the inactivated seasonal influenza vaccine on preterm and small for gestational age (SGA) births, with the aim to assess racial and socioeconomic variations in vaccine effect.

Methods

We conducted a retrospective analysis of state-wide surveillance data from Georgia for the most recent four years available at the beginning of the study, a total of 8393 live births in Georgia from January 1, 2005 through December 31, 2008. We constructed multivariable logistic regression models and calculated odds ratios (OR) estimates with corresponding 95% confidence intervals (CI) to evaluate the effect of maternal influenza vaccination on SGA (birth weight <10th percentile for gestational age) and preterm (gestational age at birth <37 weeks) births while controlling for potential confounders.

Results

Among all women, we found significant strong associations between maternal influenza vaccination and reduced odds of a preterm birth during the widespread influenza activity period [OR = 0.39, 95% CI: 0.18, 0.83]. In this period, vaccination was protective against SGA births among women at higher risk for influenza related morbidity – women enrolled in the Women, Infant and Child (WIC) program [OR = 0.20, 95% CI: 0.04, 0.98] and Black women [OR = 0.15 95% CI: 0.02, 0.94]; maternal influenza vaccination was associated with reduced odds of a preterm birth among white women [OR = 0.34, 95% CI: 0.12, 0.91] and women of higher socio-economic status [OR = 0.30, 95% CI: 0.12, 0.74].

Conclusion

Influenza vaccination during pregnancy was significantly associated with reduced odds of small for gestational age and preterm births during the widespread influenza activity period. Vaccination effects varied by socio-demographic characteristics.     

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.     

Seasonal influenza vaccine effectiveness in pre- and full-term children aged 6–23 months over multiple seasons

Introduction

This study aimed to determine the effectiveness of seasonal influenza vaccine in pre- and full-term children aged 6–23 months.

Methods

We examined a cohort of 683,354 young children (7.7% preterm) over five influenza seasons (2004–2005 to 2008–2009) in Ontario, Canada. Vaccine effectiveness was estimated using influenza-coded ambulatory visits during virologically-confirmed influenza season periods as the outcome and multivariable Cox proportional hazards modeling.

Results

Full vaccination was associated with a 19% reduction in influenza-coded ambulatory visits (HR = 0.81; 95% CI, 0.68–0.97) in all children, and an 18% reduction in full-term children (HR = 0.82; 95% CI, 0.68–0.99). We did not find significant vaccine effectiveness for preterm children. No benefit was found for partial vaccination.

Conclusions

In children younger than two years, only full influenza vaccination is associated with reduced influenza-coded ambulatory visits. Since the effectiveness of influenza vaccination in preterm children remains uncertain, further study of this highly vulnerable population is warranted.     

DNA vaccination protects against an influenza challenge in a double-blind randomised placebo-controlled phase 1b clinical trial

Background

We have developed a Trivalent DNA vaccine for influenza consisting of three plasmids expressing haemagglutinin from different seasonal influenza virus strains delivered using PMED™ (particle mediated epidermal delivery). We set out to determine whether this vaccine (with and without a molecular adjuvant DNA Encoded Immunostimulator-Labile Toxin (DEI-LT)) could protect subjects from a controlled influenza virus challenge.

Methods

Healthy adult subjects were screened for susceptibility to infection with influenza A/H3 Panama/2007/99 then vaccinated with 4 μg Trivalent influenza DNA vaccine, 2 μg Trivalent influenza DNA vaccine plus DEI-LT or placebo. Safety and serological responses to vaccination were assessed and on Day 56 subjects were challenged with A/H3 Panama/2007/99 virus.

Results

Vaccination with 4 μg Trivalent or 2 μg Trivalent/DEI-LT was well tolerated and induced antibody responses to two of the three influenza virus vaccine strains. Post challenge, subjects in the 4 μg Trivalent group (N = 27) showed reductions in disease symptoms and viral shedding compared to placebo (N = 27), with an overall vaccine efficacy of 41% (95% confidence interval (CI) = −1.5, 67.7) for ‘Any illness with or without fever’ and 53% for ‘Upper respiratory tract infection’ (95% CI = 8.0, 77.7).

Conclusion

It was concluded that PMED vaccination with 4 μg Trivalent influenza DNA vaccine was safe and elicited immunological responses that protected human subjects from influenza; this is the first report of protection of human subjects from disease by DNA vaccination.     

How do anticipated worry and regret predict seasonal influenza vaccination uptake among Chinese adults?

Objectives

To test two hypothesized models of how anticipated affect, cognitive risk estimate and vaccination intention might influence vaccination uptake against seasonal influenza.

Methods

The study collected baseline and follow-up data during the main influenza seasons (January–March) of 2009 and 2010, respectively, among 507 university students and staff of a university in Hong Kong. Following logistic regression to determine eligible variables, two mediation models of cognitive risk estimate, anticipated affect, vaccination intention and vaccination uptake against seasonal influenza were tested using structural equation modeling.

Results

Mediation analyses found that anticipated worry if not vaccinated influenced seasonal influenza vaccination uptake through its effects on either perceived probability of influenza infection (β = 0.45) or intention (β = 0.45) while anticipated regret if not vaccinated influenced vaccination uptake through its effect on intention (β = 0.45) only; anticipated regret if vaccinated impeded vaccination uptake indirectly through its effect on vaccination intention (β = −0.26) or directly (β = −0.20); perceived probability of influenza infection influenced vaccination uptake through its effect on intention (β = 0.20) or directly (β = 0.22); and finally, intention influenced vaccination uptake directly (β = 0.58).

Conclusion

The results suggest that anticipated affect seems to drive risk estimates related to seasonal influenza vaccination rather than vice versa and intention remains an important mediator of the associations of anticipated affect and cognitive risk estimate with vaccination uptake against seasonal influenza.     

Influencia del criterio de selección de pacientes para la toma de frotis en la estimación de la efectividad de la vacuna antigripal

Objective

To estimate the effectiveness of the influenza vaccine under different criteria for selecting patients for swabbing.

Method

A case-control study was performed of laboratory-confirmed cases (n = 909) and negative controls for influenza (n = 732) in the 2010-2011 to 2012-2013 seasons in Navarre (Spain). The adjusted vaccine effectiveness was estimated by including all swabs from patients with influenza-like-illness and selecting only the first two cases per physician and week.

Results

The first two patients per physician and week were less frequently vaccinated against influenza (7.9% vs. 12.5%, p = 0.021) and less often received confirmation of influenza (53.6% vs. 66.4%, p <0.001) than subsequent patients. These differences decreased after adjustment for covariates. The effectiveness of the influenza vaccine was 49% (95% CI: 23-66%) when all swabs were included and was 55% (95% CI: 27-72%) when we selected the first two swabs per week and physician.

Conclusion

The selection of the first two patients per physician and week may bias assessment of the effectiveness of the influenza vaccine, although this bias was small in the seasons analyzed.     

Live attenuated seasonal and pandemic influenza vaccine in school-age children: A randomized controlled trial

Background

The novel influenza A(H1N1pdm09) virus emerged in North America in early 2009 and rapidly spread worldwide. In this study we report the efficacy of the live attenuated monovalent H1N1pdm09 vaccine and 2009–10 seasonal influenza vaccine in a randomized double-blind placebo-controlled trial.

Methods

We enrolled 703 children aged 7–11. Each child was randomly allocated in the ratio 3:2 to receive one dose of live attenuated monovalent H1N1pdm09 vaccine or saline placebo between November 2009 and January 2010, followed after 3–10 weeks by independent random allocation to one dose of live attenuated trivalent 2009–10 seasonal influenza vaccine or saline placebo in the same ratio. Children were followed up through September 2010 with biweekly telephone calls and symptom diaries. Seasonal and pandemic influenza infections were confirmed by virologic testing of nose and throat swabs collected during acute respiratory illnesses.

Results

Overall, 30 children had confirmed influenza including 3 (0.43%) H1N1pdm09, 10 (1.4%) seasonal A(H3N2), and 17 (2.4%) influenza B. There were no significant differences in incidence rates of H1N1pdm09 or A(H3N2) between the four study arms, but receipt of the seasonal influenza vaccine was associated with a significant reduction in risk of influenza B (p < 0.01). Vaccine efficacy against confirmed H1N1pdm09 infection associated with receipt of the monovalent H1N1pdm09 vaccine was 65% (95% confidence interval, CI: −281%, 97%). Vaccine efficacies against confirmed seasonal influenza A(H3N2) and B infection associated with receipt of the seasonal influenza vaccine were 31% (95% CI: −138%, 80%) and 96% (95% CI: 67%, 99%) respectively.

Conclusions

Vaccine efficacy was consistent with other studies of the monovalent H1N1pdm09 vaccine and seasonal influenza vaccines. Our study was underpowered to provide precise estimates of vaccine efficacy due to low incidence of influenza A viruses during the study period.     

Estimates of influenza vaccine effectiveness in primary care in Scotland vary with clinical or laboratory endpoint and method—Experience across the 2010/11 season

Aim

This study examines estimation of seasonal influenza vaccine effectiveness (VE) for a cohort of patients attending general practice in Scotland in 2010/11. The study focuses on the variation in estimation of VE for both virological and clinical consultation outcomes and understanding the dependency on date of analysis during the season, methodological approach and the effect of use of a propensity score model.

Methods

For the clinical outcomes, three methodological approaches were considered; adjusted Poisson multi-level modelling splitting consultations in vaccinated individuals into those before and after vaccination, adjusted Cox proportional hazards modelling and finally the screening method. For the virological outcome, the test-negative case–control study design was employed.

Results

VE was highest for the most specific outcomes of ILI (Poisson end-of-season VE = 47% (95% CI: −69%, 83%); Cox VE = 34% (95% CI: −64%, 73.2%); Screening VE = 52.8% (95% CI: 3.8%, 76.8%)) and a virological diagnosis (VE = 54% (95% CI: −37%, 85%)). Using the Cox approach, adjusted for propensity score only gave VE = 46.5% (95% CI: −30.4%, 78.0%).

Conclusion

Our approach illustrated the ability to achieve relatively consistent estimates of seasonal influenza VE using both specific and less specific outcomes. Construction of a propensity score and use for bias adjustment increased the estimate of ILI VE estimated from the Cox model and made estimates more similar to the Poisson approach, which models differences in consultation behaviour of vaccinated individuals more inherently in its structure. VE estimation for the same data was found to vary by methodology which should be noted when comparing results from different studies and countries.     

Barriers to influenza vaccination among pregnant women

Objective

Despite pregnant women's increased morbidity and mortality from influenza, vaccination rates remain low. This study intended to evaluate barriers to pregnant women's uptake of influenza vaccine.

Study design

A survey was designed that assessed participant demographics, knowledge, beliefs, attitudes, and general experiences with seasonal and 2009 novel H1N1 influenza. Associations between patient characteristics and vaccine uptake were then assessed.

Results

88 women completed the survey. Women who correctly answered >75% of knowledge questions regarding influenza were significantly more likely to accept the influenza vaccine (seasonal: p = 0.04, H1N1: p < 0.01). Conversely, patients who declined the vaccine were more likely to hold false beliefs, such as perceiving that the vaccine was not protective (seasonal: p < 0.01, H1N1: p < .01) and that they were not at risk for influenza (seasonal: p <  0.01).

Conclusion

The reasons for influenza vaccine declination in pregnant patients include lower levels of knowledge and unfavorable attitudes regarding the safety and efficacy of the vaccine, and suggest the importance of education as a tool to improve vaccination uptake     

Effectiveness of influenza vaccination in elderly diabetic patients: A retrospective cohort study

Purpose

Studies regarding the clinical benefits of influenza vaccination in diabetic patients are limited. This study evaluated if the elderly diabetic patients who have had influenza vaccination would have benefits such as reduced medical care and mortality.

Methods

We used the universal insurance claims data from 2001 to 2009 in Taiwan to identify annual elderly patients with diabetes cohorts with (N = 4454) and without (N = 4571) influenza vaccination. The risk of developing pneumonia or influenza, respiratory failure, intensive care, hospitalization, and mortality were measured and compared between cohorts within one year of follow-up.

Results

The vaccine cohort had lower incidences of pneumonia or influenza and respiratory failure compared with the non-vaccine cohort. More importantly, the vaccine cohort had a hospitalization rate that was 11% less than the non-vaccine cohort (29.6 vs. 33.1 per 100 person-years) with an adjusted hazard ratio (HR) of 0.88 (95% CI 0.81–0.96). The vaccine cohort was also less likely to be admitted to the intensive care unit (ICU) [0.58 vs. 2.05 per 100 person-year; adjusted HR 0.30 (95% CI 0.19–0.47)] and less likely to expire [3.13 vs. 7.96 per 100 person-year; adjusted HR 0.44 (95% CI 0.36–0.54)]. Influenza vaccination reduced the hospitalization cost by 1282.6 USD, compared with patients without influenza vaccination (95% CI −2210.3, −354.8).

Conclusion

Influenza vaccination is associated with a reduced risk of morbidity, hospitalization, ICU admissions, and mortality. In addition, the hospitalization cost is reduced.     

Staying on track: A cluster randomized controlled trial of automated reminders aimed at increasing human papillomavirus vaccine completion

Objectives

To evaluate whether automated reminders increase on-time completion of the three-dose human papillomavirus (HPV) vaccine series.

Methods

Ten reproductive health centers enrolled 365 women aged 19–26 to receive dose one of the HPV vaccine. Health centers were matched and randomized so that participants received either routine follow-up (control) or automated reminder messages for vaccine doses two and three (intervention). Intervention participants selected their preferred method of reminders – text, e-mail, phone, private Facebook message, or standard mail. We compared vaccine completion rates between groups over a period of 32 weeks.

Results

The reminder system did not increase completion rates, which overall were low at 17.2% in the intervention group and 18.9% in the control group (p = 0.881). Exploratory analyses revealed that participants who completed the series on-time were more likely to be older (OR = 1.15, 95% CI 1.01–1.31), report having completed a four-year college degree or more (age-adjusted OR = 2.51, 95% CI 1.29–4.90), and report three or more lifetime sexual partners (age-adjusted OR = 3.45, 95% CI 1.20–9.92).

Conclusions

The study intervention did not increase HPV vaccine series completion. Despite great public health interest in HPV vaccine completion and reminder technologies, completion rates remain low.     

Seasonal influenza vaccine effectiveness against influenza in 2012–2013: A hospital-based case-control study in Lithuania

Background

Due to scarce information on seasonal influenza vaccine effectiveness (SIVE) against severe clinical influenza outcomes in risk populations, we conducted a case-control study to assess its effects against laboratory-confirmed influenza in hospitalized patients during the 2012–2013 influenza season.

Methods

We conducted a test-negative case-control study among ≥18 years old patients with influenza-like illness (ILI) hospitalized in two Lithuanian hospitals. Cases were influenza A(H1N1), A(H3) or influenza B positive by RT-PCR, and controls were influenza negative. Additional demographic and clinical data to assess the role of confounding were collected. SIVE and its confidence intervals (95% CI) were estimated by using multivariate logistic regression as (1 − OR) × 100%.

Results

The sample consisted of 185 subjects. Seasonal influenza vaccine uptake was 5%. Among 111 (60%) influenza positive cases, 24.3% were A(H1N1), 10.8% were A(H3) and 24.3% were influenza B cases. Unadjusted SIVE was 79% (95% CI −6% to 96%) and after the adjustment it increased to 86% (95% CI 19% to 97%).

Conclusions

Seasonal influenza vaccination in 2012–2013 was associated with reduced occurrence of laboratory-confirmed influenza, but due to low sample size the estimate of SIVE is imprecise. Given high prevalence of influenza in hospitalized ILI cases and low influenza vaccination coverage, there is a need to increase influenza vaccination rates.     

Knowledge,attitudes and vaccination coverage of healthcare workers regarding occupational vaccinations

Objectives

Immunization of healthcare workers (HCWs) is a major issue for infection control in healthcare facilities. The aim of this study was to evaluate knowledge regarding occupational vaccinations, HBV, varicella and influenza vaccination rates and attitudes towards influenza vaccine among HCWs.

Design and setting

A cross-sectional survey was conducted in two wards (Medicine and Paediatrics) of a 1182-bed teaching hospital in Paris, France.

Methods

A standardized, anonymous, self-administered questionnaire was used.

Results

Of 580 HCWs, 395 (68%) completed the questionnaire. Knowledge about the occupational vaccinations of HCWs was low. HBV (69%), tuberculosis (54%) and influenza (52%) were the most cited vaccinations. Paediatric staff was more aware of influenza and pertussis immunizations (p < .05). HBV vaccination rate was 93%, among whom 65% were aware of their immune status. Influenza vaccination rate for 2006–2007 was 30% overall, ranging from 50% among physicians to 20% among paramedical staff (p < .05). Physicians based their refusal on doubts about vaccine efficacy, although paramedics feared side effects. Influenza vaccination was associated with knowledge of vaccine recommendations [OR = 1.75, 95% CI: 1.13–2.57] and contact with patients [OR = 3.05, 95% CI: 1.50–5.91].

Conclusions

Knowledge of recommended occupational vaccinations is insufficient in HCWs, except for HBV and influenza. Although the HBV vaccine coverage of HCWs is satisfactory, a large proportion of them is unaware of immune status. Influenza vaccine coverage remains low, especially among paramedical staff because of fear of side effects. As vaccine coverage is associated with knowledge, educational campaigns should be strengthened to increase the adhesion of HCWs to vaccinations.     

Attitudes towards influenza vaccination of multi-nationality health-care workers in Saudi Arabia

Background

The compliance with influenza vaccination among health-care workers (HCWs) is known to be low. A multi-nationality survey to explore the reasons for such poor compliance has not been studied in depth.

Materials and methods

An epidemiologic survey to evaluate the compliance rates with influenza vaccination and possible associated reasons for compliance.

Results

A total of 450 survey sheets were distributed and 244 (54.2%) were completed. Of the total respondents, 51 (20.9%) were Saudi, 114 (46.7%) were other Arabs, 21 (4%) were North American, 21 (8.6%) were from UK or South Africa and 48 (19.7%) did not indicate their nationalities. There were 32 (13.1%) physicians, and 132 (54.1%) nurses. The overall influenza vaccination rate was 41% in the preceding year and 69% in the preceding 5 years, and 49.2% (n = 110) of the latter group received one to three vaccines. Of the total respondents, 156 (63.9%) report that the influenza vaccine was important, 86 (35%) report that they were not at risk of influenza, 163 (66.8%) report that the influenza vaccine was not safe and 152 (62.3%) report that influenza was not a serious illness. In a multivariate analysis, the following factors were important in choosing vaccinations: being a male, other Arab nationality, and knowing that influenza vaccine is important (P ≤ 0.01). Feeling at risk of influenza, and not using any vaccine alternatives, and that the vaccine is important for self and the patient's protection, were statistically important factors as well (P ≤ 0.05).

Conclusion

Important factors associated with increasing influenza vaccine acceptance include being a male, other Arab nationality, and knowing that influenza vaccine is important. In addition, feeling at risk of influenza, and not using any vaccine alternatives, and that the vaccine is important for self and the patient's protection, were statistically important factors as well. Thus, efforts to increase the acceptance rates should take these factors in consideration.     

Correlates of general practitioners’ recommendations to patients regarding vaccination for the 2009–2010 pandemic influenza (A/H1N1) in France: Implications for future vaccination campaigns

Background

General practitioners’ (GPs) recommendations to their patients regarding influenza vaccination is a key determinant of patient uptake of influenza vaccination.

Objectives

To study factors associated with GPs’ recommendations regarding pandemic vaccination (pvaccination) to adults ≤65 years of age (hereafter referred to as adults) at risk and not at risk of severe complications of the 2009–2010 A/H1N1 influenza.

Patients/Methods

National cross-sectional survey of 1431 French GPs. Pvaccination recommendations by GPs to adults were studied according to three categories: recommended pvaccination to at-risk adults only; recommended pvaccination to all adults; recommended against pvaccination or did not provide any advice to any adult.

Results

GPs were more likely to recommend pvaccination to at-risk than not-at-risk adults (73.4% vs 40.1%, p < 0.01). GPs who consulted official sources of information rather than news media during the pandemic were more likely to recommend pvaccination to at-risk adults only (OR = 1.78; CI 95% = 1.27–2.48) and to all adults (OR = 2.03; CI 95% = 1.42–2.92) than other GPs. GPs’ unfavorable perceptions of the risk/efficacy balance of the pandemic vaccine (pvaccine) together with their perceptions of the low severity of the disease were negatively associated with recommending pvaccination. Hospitalization of GPs’ patients because of the influenza was specifically associated with pvaccine recommendation to all adults (OR = 2.81; CI 95% = 1.98–3.99) but not with pvaccine recommendation to at-risk adults only.

Conclusion

In the pandemic context, GPs’ perceptions of disease severity and the risk/efficacy balance of the pvaccine were the major determinants of French GPs recommending pvaccination or not. To increase the general public's acceptability of vaccination policies, GPs should be adequately informed about the course of the epidemics and the safety of the vaccine.     

Negative trends from 2008/9 to 2011/12 seasons in influenza vaccination coverages among high risk subjects and health care workers in Spain

Objectives

We aim to describe influenza vaccination coverage for the Spanish population across four consecutive campaigns (2008/2009 to 2011/2012). The data was analyzed by high risk groups and health care workers (HCWs). Also, coverage trends were analyzed to assess uptake in post-pandemic seasons.

Methods

We used data from two nation-wide representative health surveys namely the 2009/10 European Health Interview Survey for Spain (N = 22,188) and the 2011–12 Spanish National Health Survey (N = 21,007) Influenza vaccination status was self-reported. We analyzed influenza vaccine coverage by age, sex, number of chronic conditions, being a heath care worker (HCWs) and nationality. Time trends for campaigns among high risk groups were estimated by a multivariate logistic regression model.

Results

We analyzed data from 43,072 subjects aged ≥16 years. As a whole, coverage decreased by 3.31% (22.57–19.26%) between the 2008/2009 and 2011/2012 campaigns with a significant decreasing trend (OR 0.92; 95% CI: 0.90–0.94).Coverage in people under 60 years with a chronic disease decreased significantly (OR 0.92: 95% CI: 0.85–0.99) during the analyzed period from 21.02% in 2008/2009 to 17.40% in 2011/2012. Among HCWs, the highest influenza vaccination coverage was achieved in 2009/2010 (31.08%) in the latest campaign coverage has almost halved (17.88%). For the 2011/2012 season and for all age groups the variables associated with a higher probability of having received the influenza vaccine were older age and presence of associated chronic conditions. Among those aged ≥60 years, immigrants had lower uptake (OR 0.60; 95% CI: 0.32–0.99).

Conclusions

Seasonal influenza vaccine uptake rates in the recommended target groups in Spain are unacceptably low and seem to be decreasing in the post pandemic seasons. Further studies are necessary to precisely identify reasons for non-compliance and barriers to influenza vaccination. Meanwhile urgent strategies to improve seasonal vaccination uptake must be discussed and implemented.     

The effectiveness of influenza vaccination in preventing hospitalizations in children in Hong Kong, 2009–2013

Background

Influenza vaccination is widely recommended every year to protect individuals against influenza virus infection and illness. There are few published estimates of influenza vaccine effectiveness against hospitalization in children or from subtropical regions.

Methods

We conducted a test-negative year-round study between October 2009 and September 2013, recruiting children 6 months to 17 years of age admitted to two hospitals in Hong Kong with a febrile acute respiratory infection. Cases were tested for influenza A and B and conditional logistic regression was used to estimate vaccine effectiveness comparing influenza vaccination history of the trivalent influenza vaccine (TIV) among patients testing positive versus negative for influenza, adjusting for age and sex and matching by calendar week of recruitment.

Results

Overall vaccine effectiveness against hospitalization with laboratory-confirmed influenza A and B was estimated to be 61.7% (95% CI: 43.0%, 74.2%). The estimated vaccine effectiveness against A(H3N2) was 36.6% (95% CI: −25.5%, 67.9%) compared to 71.5% (95% CI: 39.4%, 86.6%) for A(H1N1)pdm09 and 68.8% (95% CI: 41.6%, 83.3%) for B.

Conclusions

Vaccine effectiveness against hospitalization in children varied from year to year, but was moderate to high overall even in an area with influenza activity throughout the year.