[Show abstract][Hide abstract] ABSTRACT: In France, 2-15% of the population is affected annually by influenza, which causes significant socioeconomic disruption. Nevertheless, despite its importance for policy makers, few published studies have evaluated the impact of influenza B. Therefore, we assessed the costs associated with influenza B during 2010-2011 in France.
Cases of lab-confirmed influenza B were analyzed as part of the Influenza B in General Practice Study. Cost calculations were based on micro-costing methods according to the French Health Insurance (FHI) perspective (in Euros, 2011). Costs were compared between age groups using the Kruskal-Wallis test, and when significant, by multiple comparisons based on rank. Moreover, uncertainties were assessed using one-way sensitivity and probabilistic analyses. Overall economic burden was estimated by multiplying cost per patient, flu attack rate, and the French population.
A total of 201 patients were included in the study. We found that the mean cost associated with Influenza B was 72[euro sign] (SD: 205) per patient: 70[euro sign] (SD: 262) for younger children, 50[euro sign] (SD: 195) for older children, 126[euro sign] (SD: 180) for adults, and 42[euro sign] (SD: 18) for elderly. Thus, we observed significantly different costs between the distinct age groups (p<0.0001). Finally, the economic burden of influenza B for the FHI was estimated to be 145 million Euros (95% CI: 88-201).
Our findings highlight the important impact of influenza B and encourage further investigation on policy regarding vaccination strategies in France.
BMC Public Health 01/2014; 14(1):56. · 2.08 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: In this study, we assess how effective pandemic and trivalent 2009-2010 seasonal vaccines were in preventing influenza-like illness (ILI) during the 2009 A(H1N1) pandemic in France. We also compare vaccine effectiveness against ILI versus laboratory-confirmed pandemic A(H1N1) influenza, and assess the possible bias caused by using non-specific endpoints and observational data.
We estimated vaccine effectiveness by using the following formula: VE = (PPV-PCV)/(PPV(1-PCV)) × 100%, where PPV is the proportion vaccinated in the population and PCV the proportion of vaccinated influenza cases. People were considered vaccinated three weeks after receiving a dose of vaccine. ILI and pandemic A(H1N1) laboratory-confirmed cases were obtained from two surveillance networks of general practitioners. During the epidemic, 99.7% of influenza isolates were pandemic A(H1N1). Pandemic and seasonal vaccine uptakes in the population were obtained from the National Health Insurance database and by telephonic surveys, respectively. Effectiveness estimates were adjusted by age and week. The presence of residual biases was explored by calculating vaccine effectiveness after the influenza period. The effectiveness of pandemic vaccines in preventing ILI was 52% (95% confidence interval: 30-69) during the pandemic and 33% (4-55) after. It was 86% (56-98) against confirmed influenza. The effectiveness of seasonal vaccines against ILI was 61% (56-66) during the pandemic and 19% (-10-41) after. It was 60% (41-74) against confirmed influenza.
The effectiveness of pandemic vaccines in preventing confirmed pandemic A(H1N1) influenza on the field was high, consistently with published findings. It was significantly lower against ILI. This is unsurprising since not all ILI cases are caused by influenza. Trivalent 2009-2010 seasonal vaccines had a statistically significant effectiveness in preventing ILI and confirmed pandemic influenza, but were not better in preventing confirmed pandemic influenza than in preventing ILI. This lack of difference might be indicative of selection bias.
PLoS ONE 01/2011; 6(5):e19621. · 3.53 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: In the third season of I-MOVE (Influenza Monitoring Vaccine Effectiveness in Europe), we undertook a multicentre case-control study based on sentinel practitioner surveillance networks in eight European Union (EU) member states to estimate 2010/11 influenza vaccine effectiveness (VE) against medically-attended influenza-like illness (ILI) laboratory-confirmed as influenza.
Using systematic sampling, practitioners swabbed ILI/ARI patients within seven days of symptom onset. We compared influenza-positive to influenza laboratory-negative patients among those meeting the EU ILI case definition. A valid vaccination corresponded to > 14 days between receiving a dose of vaccine and symptom onset. We used multiple imputation with chained equations to estimate missing values. Using logistic regression with study as fixed effect we calculated influenza VE adjusting for potential confounders. We estimated influenza VE overall, by influenza type, age group and among the target group for vaccination.
We included 2019 cases and 2391 controls in the analysis. Adjusted VE was 52% (95% CI 30-67) overall (N = 4410), 55% (95% CI 29-72) against A(H1N1) and 50% (95% CI 14-71) against influenza B. Adjusted VE against all influenza subtypes was 66% (95% CI 15-86), 41% (95% CI -3-66) and 60% (95% CI 17-81) among those aged 0-14, 15-59 and ≥60 respectively. Among target groups for vaccination (N = 1004), VE was 56% (95% CI 34-71) overall, 59% (95% CI 32-75) against A(H1N1) and 63% (95% CI 31-81) against influenza B.
Results suggest moderate protection from 2010-11 trivalent influenza vaccines against medically-attended ILI laboratory-confirmed as influenza across Europe. Adjusted and stratified influenza VE estimates are possible with the large sample size of this multi-centre case-control. I-MOVE shows how a network can provide precise summary VE measures across Europe.
PLoS ONE 01/2011; 6(11):e27622. · 3.53 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: In France, the surveillance of influenza epidemics is carried out through a community-based surveillance network combining clinical and virological data. This surveillance is implemented in the Rhône-Alpes region, including the large ski resorts. In these resorts, numerous tourists are coming from France as well as from other European countries throughout the entire ski season. A specific network has been implemented in the ski resorts of the Alps (GROG-SKI) to analyse the circulation of influenza in these villages. Since winter 2001–2002, 11 GPs in seven resorts have been collecting virological specimens from patients presenting with acute respiratory infections, including both natives and visitors. During the last winter period, we compared the circulation of influenza in the GROG-SKI network with the circulation of influenza in the Rhône-Alpes region, with the exclusion of the departments of the Alps (Savoie and Haute-Savoie). Overall, from the 15th of December until the 15th of April, 105 samples were collected in the GROG-SKI network, compared with 495 in the other departments of the Rhône-Alpes region; influenza being detected in 34 (32.4%) and 187 (37.8%) specimens, respectively (p=0.2). The peaks were observed at the same period, in mid-February, with the same shift from Influenza B to Influenza A viruses by the end of March. Within the Rhône-Alpes region, the influenza epidemic was observed at the same period of time in the ski resorts and in the remaining part of the region during winter 2002–2003; both surveillance yielding identical epidemic curves. This result suggests that the tourists coming to the ski resorts are exposed to the risk of developing influenza according to the epidemic status of the region, and that they have a minor impact on the epidemiology of influenza viruses in the ski resorts.
International Congress Series 01/2004; 1263:376-380.