Randomised active programs on healthcareworkers' flu vaccination in geriatric health care settings in France: The VESTA study

Abstract

Background

Because of a lack of efficacy of influenza vaccination in elderly population, there are still numerous outbreaks in geriatric health care settings. The health care workers (HCW) flu vaccination is known to get herd immunity and decrease the impact of influenza in elderly population living in geriatric health care settings. However, the rates of vaccinated HCWs are still low in France. The French Geriatric Infection Risk Institute (ORIG) performed the VESTA study, a three-phase multicentre to identify factors limiting vaccination in HCWs, and to develop and implement active programs promoting HCWs influenza vaccination.

Objectives

To implement multicenter programs to enhance HCW influenza vaccination.

Design

It was a cluster randomised interventional studies.

Setting

43 geriatric health care settings (GHCSs), long term care and rehabilitation care settings in France.

Participants

1814 Health care workers from 20 GHCSs in the interventional group and 2,435 health care workers in 23 GHCSs in the control group.

Intervention

After the failure of a first educational program giving scientific information and. tested during the 2005–06 flu season in 43 HCSs, a second program was designed with the help of marketing experts, one year after Program 1. The objectives were to involve HCWs in the creation of “safety zones”, and to give personal satisfaction. Program 2 was tested during the 2006–07 season. 20 of the 24 HCSs from the Program 1 cluster were included in the Program 2 cluster (1,814 HCWs), and 16 of the 19 HCSs from the Control 1 cluster, plus 7 new HCSs with interest in participating, were included in the Control 2 cluster (23 HCSs; 2,435 HCWs).

Measurements

The efficacy of each program was assessed by calculating and comparing the percentage of vaccinated HCWs, from all HCSs taken together, in the program and control clusters.

Results

Program 1 failed to increase the HCW vaccination coverage rate (VCR) (Program 1: 34%; Control 1: 32%; p>0.05),). Program 2 increased the VCR in HCWs (Program 2: 44%; Control 2: 27%; Chi2 test, p<0.001) regardless their occupational group but only in the non previous vaccinated subgroup.

Conclusions

In geriatric health care centres in France, an active multicenter program giving personal satisfaction and taking into account the profile of non-vaccinated HCWs was more effective in promoting flu vaccination than a scientifically factual information program. HCW involvement is required in program implementation in order to avoid rejection of top-down information.

Abbreviations

Flu

influenza

HCS

health care setting

HCW

healthcare worker

VCR

vaccination coverage rate

Introduction

Influenza (flu) can have serious consequences in the elderly (1). In the United States, during the 1990-99 seasons, approximately 36,000 deaths were associated annually with flu epidemics, and 90% of these deaths occurred in adults aged = 65 years (2). Annual vaccination is the most effective method for preventing flu infection and its complications (3). Although the elderly have a diminished immune response to flu vaccination compared to young adults (3), annual flu vaccination has been shown to reduce their risk of pneumonia, hospital admission and death (1, 4).

Flu vaccination is recommended by the World Health Organization (WHO) (1) and the French national health authorities (5) for adults aged = 65 years. In addition, the WHO recommends vaccinating 75% of the elderly by 2010 in countries with flu vaccination policies (1), and one of the French public health objectives for 2008 (Health Act No.°2004-806, dated August 9, 2004: http://www.legifrance.gouv.fr) is to achieve a 75% flu vaccination coverage rate (VCR) in this age-group. Flu vaccination coverage in the elderly is usually greater than in other age-groups, although there is still room for improvement. A recent mail-based household survey found a

VCR of 70% in persons aged = 65 years in France during the 2005-06 flu season (6). Gavazzi et al. showed that flu VCRs ranged between 57% (rehabilitation care setting) and 93% (nursing home setting) during the 2002-03 flu season in 105 French geriatric healthcare units (7).

Healthcare workers (HCWs) in regular prolonged contact with the elderly are a potential source of nosocomial flu infection in this population. Several nosocomial flu epidemics have been reported in geriatric healthcare settings (HCSs) despite their high level of flu vaccination coverage (8, 9, 10). HCW vaccination has been shown to be effective in protecting patients, reducing the number of deaths among nursing home patients and elderly hospital patients (3, 11). Carman et al. (12) showed that an HCW flu VCR of over 50% would decrease mortality by approximately 40% in elderly patients in long-term care; they concluded that vaccinating HCWs is at least as important as vaccinating the elderly people themselves in reducing flu morbidity and mortality.

Annual flu vaccination of HCWs in contact with the elderly has been highly recommended by the Centers for Disease Control and Prevention (CDC) since 1981 and by the WHO since 1997, and is now recommended by many national health authorities (1, 5, 11). Annual flu vaccination of HCWs in contact with high-risk patients has been included in the French vaccination calendar since 2000 (13). HCW vaccination also reduces influenza infection in staff and decreases absenteeism (14, 15). Flu VCRs, however, are usually low in HCWs and vary with age, occupational group and facility type (11). In France, 38% of the overall HCW population was vaccinated during the 2004-05 flu season, according to a SOFRES survey (http://www.tns-sofres.com/etudes/sante/220905_grippe2005.pdf) carried out for the French Influenza Study and Information Group (GEIG: Groupe d'Etude et d'Information sur la Grippe); and our own preliminary survey found that 31% of HCWs working in 107 geriatric HCSs were vaccinated during the 2002-03 season (7).

The low flu VCR of HCWs in regular prolonged contact with institutionalized elderly patients led the French Geriatric Infection Risk Institute (ORIG: Observatoire du Risque Infectieux en Gériatrie) to run the VESTA study. ORIG is a health care research network devoted to improving the understanding of the causes of infection risk in the elderly and to developing offensive counter-strategies. VESTA was a multiphase, multicenter study to identify factors limiting vaccination in HCWs working in French geriatric HCSs (diagnosis phase), (data not shown), develop and implement active programs promoting HCW flu vaccination (interventional phase), and finally assess the efficacy of active programs (assessment phase). The present article reports the results of the second active program implemented as part of the VESTA study as compared to the results of the first program.

Methods

The VESTA Study

VESTA was a cluster randomised interventional study performed in geriatric HCSs. Two programs (Program 1 and Program 2) were consecutively developed and assessed.

Program 1 was implemented between October 1 and November 15, 2005. Results are published elsewhere (16). HCSs that agreed to participate were randomly allocated to two clusters: one (Program 1 cluster) received the active program at the beginning of the flu season, while no action was performed in the second (Control 1) cluster. Two weeks after the end of Program 1, HCW flu VCR was assessed by questioning the HCWs who agreed to participate in the study about their 2005-06 flu vaccination status (assessment phase: from December 1 to December 15, 2005).

Program 2 was implemented between November 1 and December 5, 2006. HCSs that had been allocated to the Program 1 cluster were allocated to the Program 2 cluster, and those allocated to the Control 1 cluster to the Control 2 cluster. The program 2 cluster received the active program at the beginning of the flu season, while no action was performed in the Control 2 cluster. Program 2 efficacy was assessed between December 10 and December 20, 2006.

Participants

A call for participation was carried out in long-term care facilities and rehabilitation care units throughout France. Department heads wishing their HCS to participate in the study designated a local investigator and contacted ORIG.

In each centre, all the HCWs in regular contact with elderly patients and present at the time of the study could be included in the study, if they individually agreed to participate: i.e., physicians (geriatricians and residents), nurses (nurses and head nurses), nursing auxiliaries, and other workers (physical therapists, occupational therapists, etc.). Nursing or nursing auxiliary students were excluded from the study.

Active Programs

Program 1 was developed from diagnostic data obtained from one focus group, one opinion poll, and several open and semi-guided interviews. The objective of Program 1 was to convince HCWs to get vaccinated against flu by giving them information that would clear up all their fears and doubts and develop their altruism (HCW flu vaccination having a beneficial effect on their elderly patients).Methods are published elsewhere (16). Briefly, the program was educational. It included a slide-show (52 slides + 4 short movies), a leaflet, and an investigator guide. In each HCS, after informing the head of department and the occupational medicine department, the local investigator (with the help of the guide) organized information sessions for the HCWs. The slide show, entitled „Myths and Reality about Flu Vaccination“, was shown during the information sessions. The 52 slides were intended to expose myths to realities: for example, the myth that „the vaccine can cause flu“ was

contradicted by the reality that „the vaccine does not cause flu“. Three of the four short movies were interviews with physicians and the fourth, which was humoristic, showed an elderly patient asking his HCW to get vaccinated. The leaflet summarized the slide-show, and was distributed at the end of each information session.

Program 2 was developed from diagnostic data and the results of Program 1. Three marketing experts were generously involved in the project; they participated in a meeting held on October 13, 2006, chaired by the chief executive officer of the Euro RSCG Life France business consultancy. Program 2 was incentive. Its objective was to involve HCWs in the creation of „safety zones“ which the flu virus could not „get through“. The program included two kits: Kit 1 was intended to improve vaccination coverage and Kit 2 to reward HCSs showing increased vaccination coverage. Kit 1 included a slide show, posters, two booklets/leaflets, and rubber bracelets. In each HCS, the local investigator contacted a few of the HCWs previously identified as opinion leaders in the HCS to support him/her in promoting flu vaccination. The HCWs who agreed to promote vaccination showed the „Myths and Reality about Flu Vaccination“ slide-show, slightly modified so as to answer colleagues' future questions. Posters indicating that the department was combating flu were displayed on the HCS doors. One leaflet was distributed by the HCWs to families visiting their elderly relatives, and the other was kept for the HCWs themselves, providing answers to their main concerns about flu and vaccination. A rubber bracelet bearing the message „All together against flu“ was given to all vaccinated HCWs. When the flu VCR in the HCS reached >50%, the HCS received Kit 2. Kit 2 mainly comprised posters indicating that the department had reached its objective. These posters were displayed on the HCS doors and seen by the HCWs, the elderly persons and their families.

Data Collection

Each local investigator recorded information on two dedicated questionnaires.

The HCS questionnaire, completed ahead of program implementation, included items on hospital type, facility type, flu vaccination policy and organization, HCW occupational groups, and vaccination status for the 2004-05 flu season.

The HCW questionnaire was completed, for each HCW who agreed to participate in the study, after each program implementation. It included items on occupational group, flu vaccination status before (the previous year) and after implementation of the active programs, reasons for non-vaccination (unwillingness or impossibility), and intention to get vaccinated for the forthcoming season.

Assessment Criteria

The main criterion was the percentage of vaccinated HCWs (flu VCR) before and after implementation of the active program in each cluster, for all HCSs taken together.

The secondary criterion was flu VCR before and after implementation of each active program in each cluster (for all HCSs taken together) according to previous flu vaccination status (vaccinated or non-vaccinated for the previous season), and/or to occupational group. Three occupational groups were defined: physicians, nurses, and nursing auxiliaries.

The observational criteria were: willingness to be vaccinated despite this being in fact impossible during the assessment season (Program 1 only), and willingness to get vaccinated for the forthcoming flu season (Program 1 and Program 2) in each cluster (for all HCSs taken together).

Statistical Analysis

Statistical analyses were performed under the supervision of the study coordinator on a Voozanoo version specifically developed for the VESTA Study (EpiConcept, Paris, France), Epi-Info version 6.04 (French version available on http://www.epiconcept.fr/html/epiinfo.html), and SAS 8 software (SAS Institute, Inc., Cary, NC).

A description of the participants (HCSs and HCWs) was performed on all questionnaire variables. For each variable, percentages were calculated using available data (missing data ignored).

The percentage of vaccinated HCWs was calculated using data from all the HCSs taken together. One-sided Chi_ test was used to compare Program and Control clusters. The significance thresholds were set at 0.05.

Ethical Considerations

As this study did not affect medical practice, it did not need to be submitted for ethics committee approval, in line with current French legislation. All questionnaire data were rendered anonymous using a procedure submitted to and approved by the CNIL (Commission Nationale de l'Informatique et des Libertés), the French data protection commission (authorization number AR 096228).

Before inclusion, all HCWs in the HCS at the time of the study were informed of the study objectives and requirements, by means of a poster displayed in the department.

Results

Study Follow-up

53 HCSs (4,355 HCWs) agreed to participate in the study. Of these 53 HCSs, respectively 27 and 26 were randomly allocated to the Program and Control clusters. During the study, 7 HCSs dropped out from the Program cluster and 10 from the Control cluster, and 7 HCSs having heard about the VESTA study expressed interest in participating and were included in the Control cluster. Finally, 24 Program and 19 Control HCSs participated in Program 1, and 20 Program and 23 Control HCSs in Program 2. Figure 1 shows the flow of HCSs participating in the study through each stage.

Figure 1.

Flow of Health Care Settings (HCSs) Participating in the VESTA Study through each Stage

∗ 7 HCSs having heard about the VESTA study and expressing an interest in participating in the study were included

Program 1 Assessment

Results of the first program are published elsewhere (16). To summarize, 1,201 HCWs present at the time of the study in the 24 Program 1 cluster HCSs (63%) and 1,144 HCWs present at the time of the study in the 19 Control 1 cluster HCSs (66%) participated in the study. HCW flu VCR increased in both clusters: from 29% for the 2004-05 season to 35% for the 2005-06 season in the Program 1 cluster, and from 25% to 32% in the Control 1 cluster. No statistically significant difference was observed between the Program 1 and Control 1 clusters in terms of percentage of vaccinated HCWs for the 2005-06 season (34% versus 32%, respectively; Chi_ test; p>0.05), which indicated that the program was ineffective (Table 1). However, if the results indicated that the program 1 did not encourage non-vaccinated HCWs to be vaccinated, it reinforced the choice of the vaccinated HCWs (Table 2). This results were significant only in the vaccinated nursing auxiliaries subgroup (Table 2).

Table 1.

Program 1 and 2 Assessment: Flu Vaccination Coverage Rate (VCR) in each Cluster

Parameters	Program 1 Cluster	Program 1 Control 1 Cluster	p-value§	Program 2 Cluster	Program 2 Control 2 Cluster	p-value§
Study dates
Implementation of program	Oct. 1-Nov.	15, 2005		Nov. 1-Dec.	5, 2006
Assessment of program	Dec. 1-Dec.	15, 2005		Dec. 10-Dec.	20, 2006
Main characteristics of the settings participating in the study
Healthcare settings: N	24	19	-	20	23	-
Healthcare workers (HCWs) present at the time of the study: N	1,918	1,728	-	1,814	2,435	-
HCWs participating in the study: N (%)	1,201 (63%)	1,144 (66%)	-	1,335 (74%)	1,539 (63%)
Vaccination coverage rate (VCR) at baseline∗	28%	25%	>0.05	31%	21%	<0.05
Primary criterion:
VCR for the relevant† season	34%	32%	>0.05	44%	27%	<0.05
Secondary criteria:
VCR for the relevant† season according to the previous‡ vaccination: %
HCWs vaccinated for the previous† season (revaccinated HCWs)	86%	67%	<0.001	81%	81%	0.39
HCWs not vaccinated for the previous‡ season (newly vaccinated HCWs)	25%	22%	>0.05	25%	12%	<0.001
VCR by occupational group: %
Physicians	73%	64%	<0.05	91%	63%	<0.01
Nurses	33%	36%	>0.05	49%	27%	<0.01
Nursing auxiliaries	28%	27%	>0.05	36%	20%	<0.01
VCR by previous‡ vaccination status and occupational group: %
Vaccinated physicians	93%	79%	<0.05	93%	88%	0.29
Vaccinated nurses	83%	77%	>0.05	82%	80%	0.65
Vaccinated nursing auxiliaries	85%	55%	<0.001	76%	77%	0.49
Non-vaccinated physicians	62%	58%	>0.05	75%	39%	0.03
Non-vaccinated nurses	26%	28%	>0.05	25%	11%	<0.001
Non-vaccinated nursing auxiliaries	22%	18%	>0.05	23%	10%	<0.001

^∗2004-05 flu season; † 2005-06 season for Program 1 and 2006-07 season for Program 2; ‡ 2004-05 season for Program 1 and 2005-06 season for Program 2; § Chi² test

Table 2.

Baseline Characteristics of the Health Care Settings (HCSs) Participating in Program 2 Assessment, by Cluster

Characteristics	Program	Control
Healthcare Settings	N=20	N=23
Hospital type	Regional/teaching hospital	45%	42%
	General hospital	31%	25%
	Other	24%	33%
Facility type	Long-term care facility	60%	73%
	Rehabilitation care unit	40%	27%
	Both	14%	12%
	Written (yes)	38%	33%
	Delivered by
	- Occupational physician	40%	37%
	- HCS/hospital manager	31%	30%
	- CLIN∗	19%	17%
Vaccinators	Occupational physician	52%	51%
	Self-administered	41%	44%
	Other	7%	5%
Place of vaccination	In the hospital in which the HCW worked	57%	50%
Time of vaccination	During work time	38%	42%
Healthcare workers participating in the study		N=1,335	N=1,539
Occupational group	Doctors (geriatricians) and residents	10%	11%
	Nurses (nurses, head nurses)	26%	22%
	Nursing auxiliaries	54%	51%
	Other	10%	16%

^∗CLIN: Comité de lutte contre les infections nosocomiales (French nosocomial infection prevention commitee

Program 2 Assessment

Table 2 presents the main characteristics of the HCSs participating in the Program 2 assessment part of the VESTA study

1,335 HCWs present at the time of the study in the 20 HCSs of the Program 2 cluster (74%) and 1,539 HCWs present at the time of the study in the 23 of the Control 2 cluster (63%) participated in the study. In both clusters, approximately half of these HCWs were nursing auxiliaries and a quarter nurses (Table 3).

HCW flu VCR increased in the Program 2 cluster: 31% for the 2004-05 season, 38% for the 2005-06 season, and 44% for the 2006-07 season. In the Control 2 cluster, it increased from 21% for the 2004-05 season to 28% for the 2005-06 season, and then remained stable (27% for the 2006-07 season).

A statistically significant difference was observed between the Program 2 and Control 2 clusters in terms of percentage of vaccinated for the 2006-07 season (44% versus 27%; Chi² test, p<0.05). However results are different according to the basal vaccinated status of HCW; no statistically significant difference (Chi² test, p>0.05) was observed between the Program 2 and Control 2 clusters in revaccinated HCWs groups (i.e. group vaccinated for both the 2005-06 and 2006-07 seasons):(Table 2). A statistically significant difference (Chi² test, p<0.01) was observed in the percentage of HCWs not vaccinated for 2005-06 but vaccinated for the 2006-07 season: the percentage of newly vaccinated HCWs was 12% in the Control 2 cluster and 25% in the Program 2 cluster (Table 2). These result indicated that Program 2 tended to encourage non-vaccinated HCWs to be vaccinated.

Flu vaccination rates for the 2006-07 season differed according to occupational group in both clusters, and in each occupational group, a statistically significant difference in the percentage of vaccinated HCWs was observed between the two clusters (Table 2). This result indicated that Program 2 was effective in all occupational groups. Non-vaccinated nurses and non vaccinated nursing auxiliaries were particularly receptive to Program 2 (Table 2).

There was no statistical significant difference in the percentage of HCWs claiming that they wished to be vaccinated for the 2007-08 season between the Program 2 and Control 2 clusters (54% versus 48%, respectively; Chi_ test, p>0.05).

Discussion

HCWs are exposed to influenza infection both in the general community (household contacts, public transport, etc.) and at the workplace (close proximity to patients, and constant flow of visitors and co-workers). HCWs in regular and prolonged contact with elderly people are therefore a potential source of nosocomial flu infection. As flu may be serious for the elderly, and for institutionalized elderly people in particular, vaccinating HCWs working in geriatric HCSs is therefore at least as important as vaccinating the elderly people themselves, and is recommended by the WHO and by many national health authorities (1, 5, 11).

The results of the present study showed that, before active programs were implemented, flu vaccination coverage in HCWs in French geriatric HCSs was low (23% for the 2004-05 flu season). These findings are consistent with those reported for HCWs in Europe for the 2000-01 flu season (12% to 25%) (17), and in our own preliminary survey (31% for the 2002-03 season) (7). They match the mean VCRs reported for medical and non-medical HCWs in other French studies: 20% of the Besançon teaching hospital staff for the 2003-04 season (18); 31% of the Croix-Rousse Hospital (Lyon) staff for the 2004-05 season (19); 12% of the HCWs of the Clermont-Ferrand teaching hospital for the 2003-04 season (20); and 38% of the staff of old people's homes according to a TNS SOFRES healthcare survey (http://www.sante.gouv.fr/htm/dossiers/grippe/enquete_vaccin_pro.htm). These studies also showed that flu VCRs varied with occupational group, physicians getting vaccinated more often than nurses and nursing auxiliaries. Numerous studies have already found that non-physician HCWs were less frequently vaccinated than physicians in geriatric (18, 19) and other at-risk HCSs.

The results of our first program showed that Program 1 did not improve vaccination coverage: 35% of the HCWs from the Program 1 cluster versus 32% of the HCWs from the Control 1 cluster HCWs were vaccinated during the Program 1 season (16),. Program 1 was primarily educational, mainly intended to raise the barriers to influenza vaccination identified during the VESTA diagnosis phase (by means of the „Myths and Reality about Flu Vaccination“ slide-show). This was done by providing each HCW with factual (scientific) information, via the local investigator (information sessions), and „experts“ (physicians) or hierarchic superiors (movies). Program 1 also tried to develop HCWs' altruism (e.g., a photo of an elderly person was shown in each slide, and in the last movie an elderly patient asked his HCW to be vaccinated: HCWs are to be vaccinated for the benefit of their elderly patients). The failure of Program 1 confirmed that not all active programs are successful and that there is resistance to active flu vaccination programs (21, 22). This failure was, however, informative. It showed that, to be effective, active programs need to restore a climate of confidence in knowledge sources on the part of HCWs, to promote „self-protection“ in contrast to the protection of elderly people, and to involve more than one flu vaccine promoter (local investigator). It further showed that programs should not be moralizing, exclusively factual, and providing top-down scientific knowledge (which may lead to rejection), but need to be adapted to target occupational groups.

As recommended by Hofmann et al. (21), an iterative approach was thus adopted to improve flu vaccination coverage, and a second program was developed using the experience gained from Program 1. The results of the Program 2 of the VESTA study showed an improvement of vaccination coverage: 44% of the HCWs from the Program 2 cluster versus 27% of those from Control 2 cluster were vaccinated during the Program 2 season. Program 2 took into account the profile of non-vaccinated HCWs identified in the diagnosis phase of the VESTA study: i.e., female (84%), aged between 20 and 40 years (51%), mainly working as nursing auxiliaries (46%), afraid of adverse events (52%), unaware of the vaccination status of their immediate superior (74%), not planning to be vaccinated in the future (70%), not considering the vaccine to be personally advantageous (49%), and believing that there are other means to prevent flu (e.g., homeopathy) (data non shown). Its objective was to give personal satisfaction to the vaccinated HCWs before giving them collective satisfaction: the rubber bracelets indicated that the HCW belonged to a group, the group of vaccinated HCWs combating flu; and the Kit 2 posters showed that the HCS had succeeded in this combat. The success of Program 2 showed that personal satisfaction was the key to HCW flu vaccination.

As Program 2 was developed with the help of sales and marketing experts, it can be concluded that their help is useful in developing saleable active programs. However, as HCW VCRs remained below target (i.e., 50% (12)), other sales and marketing tools or other methods should be used so as better to promote flu vaccination. Hofmann et al. (21) reported that the most effective of the six programs tested between 1985 and 2002 to improve flu vaccination coverage in the US included festive vaccination sessions with educational games, free refreshments and a lottery for vaccines meaning that probably multicomponent programs combining convenient, educational and incentive aspects seem to be the most effective strategies to increase vaccination rates (23, 23).

This study, however, presents some limitations. First, the study did not evaluate long term efficacy. Few interventional studies addressed improvement efforts aimed at long-term HCW immunization (23). As this study is to our knowledge one of the first multicenter studies evaluating and demonstrating the efficacy of one active flu vaccination program (Program 2), it was important to know if the intervention was effective in the early term (most of the studies evaluating flu vaccination programs were performed in a single centre). For the same reasons, it is now necessary to measure the long-term efficacy of program 2, which has not yet been done. Secondly, in longitudinal clinical studies, changes in outcome measures are due to numerous factors: i.e., natural history, Hawthorne, placebo and treatment factors (24). In the present as in clinical studies, treatments (i.e., active programs) were the factors of interest, with numerous other factors interfering. The increase in flu VCR observed in the overall French HCW population (15% for the 2002-03 season; 48% for the 2004-05 season), which has been attributed to national flu vaccination campaigns regularly initiated by the French health authorities since 1999 (www.hcsp.fr/hcspi/explore.cgi/a_mt_190506_grippe_pro.pdf), can be assimilated to a „natural history“ effect: HCW vaccination rates are increasing. As observed for patients in clinical trials („Hawthorne“ effect), the mere fact that Control cluster HCSs were included in the study may have increased their vaccination coverage. The fear of pandemic flu which was present for the 2005-06 season may also have modified VCRs, although its precise effect is hard to assess (increase in the demand, stock outage?). Thirdly, only HCWs agreeing to participate were included in the study and no information was collected on HCWs not included in the study. Therefore, a recruitment bias can not thus be excluded. This recruitment bias can explain the statistically significant difference observed between the Control 2 and Program 2 clusters before the implementation of the active programs (i.e., for the 2004-05 season). The 7 centres included in the Control cluster between the implementation of the two active programs probably differed from the other centres that had immediately agreed to participate in the study. Finally, as Program 2 was developed and applied after Program 1, it was probable that a small part of the effect of Program 2 was due to Program 1. However, the HCWs participating in Program 1 and Program 2 were not necessarily the same (retirement, recruitment, etc.).

Conclusions

In geriatric HCSs in France, an active multicenter program giving personal satisfaction and taking into account the profile of non-vaccinated HCWs was more effective than a scientifically factual information program in promoting flu vaccination. Involvement of HCWs in program implementation is required to avoid rejection of top-down information. Finally, long term efficiency of such program needs further evaluation.

Competing interests: None of the authors have non-financial competing interests in relation to this manuscript. JLG, BL and BdW have no financial competing interests. MRT, YFZ, and GG received unrestricted funds from Sanofi Pasteur MSD. FC is consultant for Roche, GlaxoSmith-Kline, Avenits, Chiron-Novartis. FP is consultant for Servier.

Authors' contributions: MRT, YFZ, and GG meet conditions (1), (2), and (3), and JLG, BL, BdW, FC and FP meet conditions (1) and (3): (1) substantial contributions to conception and design, or acquisition of data, or analysis and interpretation of data; (2) drafting the article or revising it critically for important intellectual content; and (3) final approval of the version to be published.

Acknowledgments: The authors thank Laurence Davin (medical marketing product manager, Blédina, France), Marie-Ange Faure (chief executive officer, Euro RSCG Life France), Laurent Mathieu (trade marketing manager, Nestlé Walters), and Anne-Céline Guyon for their informed advice and precious help in the conception of the active flu programs. Thanks are extended to Fabienne Péretz (independent medical writer) for her help in preparing this article. The authors also thank the investigators involved in data collection: Ms. Icard and Ms. Escande, Allauch; Mr. Decle, Beauvais; Ms. Oulerich, Bischwiller; Ms. Fauchier, Brest; Ms André-Fouet, Caluire et Cuire; Dr. Réveil, Charleville-Mézières; Ms. Hauler, Colmar; Ms. Glaise and Ms. Navarro, Compiègne; Dr. Paillaud and Ms. Bouchema, Créteil; Dr. Bentchikou, Dannemarie; Pr. Pfitzenmeyer, CHU Dijon; Ms. Hajjar, Dourdan; Ms. Mitrail, Dreux; Dr. Lutzler, Embrun; Ms. Delavelle, Epernay; Ms. Oulerich, Epsan; Dr. Monnier and Ms. Deltour, Evian; Dr. Bonnet, Fort de France; Ms. Bussy, Ms. Lalhou, Meaume, and Ms. Petit, Ivry/Seine; Dr. Polderman and Ms. Corbain, La Charité sur Loire; Dr. Marchal, La Musse; Ms. Bonin and Ms. Cognard, Le Creusot; Dr. Elies, Liancourt; Pr. Puissieux and Ms. Huvent, Lille; Dr. Rouillat, Lyon; Dr. Wang, Metz; Ms. Rashilas and Ms. Gressier, Montpellier; Dr. Plat, Narbonne; Ms. Strubel, Nimes; Ms. Rahire, Noyon; Dr. Celles, Orange; Ms. Chahwakilian, Paris; Ms. Giraud, Paris; Ms. Marinaro, Perpignan; Dr. Paccalin, Poitiers; Dr. Placines, Pontacq; Ms. Amamra, Pontoise; Ms. Delavelle, Reims; Ms. Cattenoz, Rennes; Ms. Marc, Rouen; Mrs. Richard, Sainte Menehould; Mrs. Diana, Saint-Etienne; Dr. Bentchikou, Saint-Morand; Ms. Cayon-Glayere, Saint-Symphorien-sur-Coise; Dr. Metzger, Soissons; Ms. Fernandez and Ms. Dick, Strasbourg; Ms. Hifdi, Toulouse; Ms. Croce and Mr. Baali, Tullins; Ms. Hoffet-Guilo, Uzès; Dr. Gasnier, Vic-en-Bigorre; Dr. Trivalle, Villejuif; and Ms. Escojido, Villeneuve les Avignon.