The effect of social deprivation on the dynamic of the SARS-CoV-2 infection in France

Background

The association between health inequalities and the SARS-CoV-2 infection dynamic remains to be studied in France. The objective of this study was to analyse the relationship between an area-based deprivation indicator and SARS-CoV-2 infection indicators, during four epidemic waves running from August 4th 2020 to January 27th 2021 (second wave), January 28th to June 24th 2021 (third wave), June 25th to October 28th 2021 (fourth wave), and October 29th 2021 to March 29th 2022 (fifth wave).

Methods

We analysed weekly indicators of SARS-CoV-2 infection, extracted from the national testing information system: incidence, positivity and testing rates. The associations of these outcomes with the European Deprivation Index (EDI) quintiles were estimated with negative binomial generalized additive models adjusted for epidemic waves, population density (sparsely, moderately, densely populated), region (random effect) and interactions between epidemic waves and the variables EDI, population density, and region.

Results

The most deprived areas had a higher positivity rate than the least deprived ones during the second, third and fourth waves, but a lower rate during the fifth wave. They also had higher incidence during the third and fourth waves, but a similar incidence than the least deprived areas during the second wave, and even a lower rate during the fifth wave. The testing rate was lower in the most deprived areas than elsewhere, irrespective of the epidemic waves.

Conclusions

People living in the most deprived areas were less likely to be tested and more likely to test positive than people living in less deprived areas. The lower incidence, positivity and testing rates during the fifth wave in the most deprived areas may be explained by the enacted change in policy whereby screening tests were no longer free. These findings may reflect structural differences in access to care and lower capacity to benefit from prevention measures by deprived populations.

Key messages

• People living in the most deprived areas were less likely to be tested for COVID-19 irrespective of the epidemic waves.

• Health authorities should address the issues of social inequalities more rapidly and target prevention strategy to disadvantaged populations.

Trends and disparities in breastfeeding initiation in France between 2010 and 2016: Results from the French National Perinatal Surveys

Breastfeeding (BF) initiation rates in French maternity units are among the lowest in Europe. After increasing for several years, they decreased between 2010 and 2016, although several maternal characteristics known to be positively associated with BF in France were more frequent. We aimed to (1) quantify adjusted trends in BF initiation rates between 2010 and 2016; (2) examine associations between BF initiation rates and newborn, maternal, maternity unit, and department‐level characteristics. Using data from the 2010 (n = 12,224) and 2016 (n = 11,089) French National Perinatal Surveys, we analysed BF initiation (exclusive, mixed, and any) through a succession of six mixed‐effect multinomial regression models, progressively adding adjustment covariates. Adjusted exclusive and any BF initiation rates decreased by 9.6 and 4.5 points, respectively, versus by 7.7 and 1.8 points, respectively, in the crude analysis. In both years, adjusted exclusive and any BF initiation rates were lowest in the following categories of mothers: low education level, single, high body mass index and multiple or premature births. Exclusive BF initiation decreased most in primiparous mothers, those with the lowest household income, mothers that had a vaginal delivery, women born in an African country and those who delivered in a maternity unit without Baby‐Friendly Hospital Initiative designation. The 2010–2016 decrease in BF initiation rates in France cannot be explained by changes in mothers' characteristics; quite the opposite, adjustment increased its magnitude. Additional efforts should be put in place to understand why this decrease is particularly sharp in some subgroups of mothers.

While some maternal characteristics previously known to be positively associated with breastfeeding (BF) in France were more frequent in 2016 than 2010, any BF initiation rate in maternity units in France decreased by 2 points (from 68.7% to 66.7%), and exclusive BF by 8 points (from 60.3% to 52.2%). Even greater decreases (4.5 and 9.6 points, respectively) were observed after adjusting for the characteristics of mothers, newborns, maternity units, and departments.

Between 2010 and 2016, the largest decreases in adjusted exclusive BF initiation rates were observed in primiparous mothers, those with the lowest household income, mothers that had a vaginal delivery, women born in an African country and those who delivered in a maternity unit without Baby‐Friendly Hospital Initiative designation.

Noncompliance to blood donor selection criteria by men who have sex with men - Complidon 2017, France

BACKGROUND AND OBJECTIVES

In France, blood donation deferral for men who have sex with men (MSM) was reduced from permanent to 12 months in July 2016. Assessing noncompliance (rate and reasons) with this criterion is important to maintain a high level of viral safety in blood products.

MATERIALS AND METHODS

An anonymous online survey (Complidon) of a sample of blood donors was conducted in 2017. Data were post-stratified to be representative of all those who donated blood between July 2016 and December 2017. A multivariable analysis was performed to assess factors associated with noncompliance.

RESULTS

Among male donors, 0·73% [95% CI: 0·63-0·83] reported having sex with men in the 12 months preceding their donation. Factors associated with noncompliance were as follows: young age, a low educational level, concerns about privacy, and better knowledge of donor selection criteria and the window period than compliant men. More than half of noncompliant MSM donors (57·6% [95% CI: 50·6-64·3]) felt that sexual orientation should not be a criterion for donation, 47·2% [95% CI: 40·4-54·0] did not disclose their male-to-male sexual relations in order to avoid being excluded from donating, 40·5% [95% CI: 34·0-47·4] reported using condoms and 21·8% [95% CI: 16·7-27·9] had the same male partner for at least 12 months.

CONCLUSION

Complidon showed that compliance with blood donation criteria in MSM was high, but not optimal, especially among younger men. HIV residual risk did not increase after the implementation of 12-month deferral. Data from Complidon helped French policymakers to assess the additional HIV risk posed by increased access to blood donation for MSM.

The evolving blood donor deferral policy for men who have sex with men: impact on the risk of HIV transmission by transfusion in France

BACKGROUND

Blood donation deferral for men who have sex with men (MSM) in France was reduced from permanent to 12 months in July 2016. To inform a further reduction of the deferral period, an HIV risk assessment was conducted with two scenarios: S1, 4-month deferral; S2, 4-month deferral only in the case of more than one sexual partner (i.e., similar to other blood donors).

METHODS

Baseline HIV residual risk (RR) was calculated from July 2016 to December 2017, using the Incidence Rate-Window Period method. The impact of both scenarios on RR was assessed using data from surveys on MSM and blood donors, to estimate 1) the number of additional MSM expected to donate in each scenario and 2) HIV incidence among these donors.

RESULTS

Baseline HIV RR was estimated at 1 in 6,380,000 donations. For S1, an additional 733 MSM donors, and an additional 0.09 HIV-positive donations were estimated, yielding an unchanged RR of 1 in 6,300,000. For S2, these numbers were estimated at 3102 and 3.92, respectively, yielding an RR of 1 in 4,300,000. Sensitivity analyses showed that, under worst-case assumptions, the RR would equal 1 in 6,225,000 donations for S1 and 1 in 3,000,000 for S2.

CONCLUSION

For both scenarios, the HIV RR remains very low. For S1, the risk is identical to the baseline RR. For S2, it is 1.5 times higher, and sensitivity analysis shows that this estimate is less robust than for S1. The French Minister of Health announced that S1 will be implemented in April 2020.

Dengue serosurvey after a 2-month long outbreak in Nîmes, France, 2015: was there more than met the eye?

Clusters of dengue cases have recently become more frequent in areas of southern France colonised by the vector mosquito Aedes albopictus. In July 2015, a 2-month outbreak of dengue virus serotype 1 (DENV-1) was reported in Nîmes. Aim: We conducted a serosurvey in the affected area at the end of the vector activity period to determine the true extent of dengue transmission. Methods: We collected capillary blood from consenting household members, and information on their medical and travel histories, and exposure to mosquito bites. Recent infections were identified using IgM and IgG anti-DENV ELISA, followed, when positive, by plaque reduction neutralisation tests on serum against DENV 1–4 and West Nile virus. The prevalence estimator was calibrated on reference demographic data. We quantified the spatial clustering of dengue cases within the affected community and inferred the transmission tree. Results: The study participation rate was 39% (564/1,431). Three of 564 participants tested positive for DENV-1 infection (after marginal calibration, 0.41%; 95% confidence interval: 0.00–0.84). The spatial analysis showed that cases were clustered at the household level. Most participants perceived the presence of mosquitos as abundant (83%) and reported frequent mosquito bites (57%). We incidentally identified six past West Nile virus infections (0.9%; 95% CI: 0.2–1.6). Conclusion: This serosurvey confirms the potential for arboviral diseases to cause outbreaks − albeit limited for now − in France and Europe.

Mapping influenza activity in emergency departments in France using Bayesian model-based geostatistics

BACKGROUND

Maps of influenza activity are important tools to monitor influenza epidemics and inform policymakers. In France, the availability of a high-quality data set from the Oscour^® surveillance network, covering 92% of hospital emergency department (ED) visits, offers new opportunities for disease mapping. Traditional geostatistical mapping methods such as Kriging ignore underlying population sizes, are not suited to non-Gaussian data and do not account for uncertainty in parameter estimates.

OBJECTIVE

Our objective was to create reliable weekly interpolated maps of influenza activity in the ED setting, to inform Santé publique France (the French national public health agency) and local healthcare authorities.

METHODS

We used Oscour^® data of ED visits covering the 2016-2017 influenza season. We developed a Bayesian model-based geostatistical approach, a class of generalized linear mixed models, with a multivariate normal random field as a spatially autocorrelated random effect. Using R-INLA, we developed an algorithm to create maps of the proportion of influenza-coded cases among all coded visits. We compared our results with maps obtained by Kriging.

RESULTS

Over the study period, 45 565 (0.82%) visits were coded as influenza cases. Maps resulting from the model are presented for each week, displaying the posterior mean of the influenza proportion and its associated uncertainty. Our model performed better than Kriging.

CONCLUSIONS

Our model allows producing smoothed maps where the random noise has been properly removed to reveal the spatial risk surface. The algorithm was incorporated into the national surveillance system to produce maps in real time and could be applied to other diseases.

Improving regional influenza surveillance through a combination of automated outbreak detection methods: the 2015/16 season in France

The 2014/15 influenza epidemic caused a work overload for healthcare facilities in France. The French national public health agency announced the start of the epidemic – based on indicators aggregated at the national level – too late for many hospitals to prepare. It was therefore decided to improve the influenza alert procedure through (i) the introduction of a pre-epidemic alert level to better anticipate future outbreaks, (ii) the regionalisation of surveillance so that healthcare structures can be informed of the arrival of epidemics in their region, (iii) the standardised use of data sources and statistical methods across regions. A web application was developed to deliver statistical results of three outbreak detection methods applied to three surveillance data sources: emergency departments, emergency general practitioners and sentinel general practitioners. This application was used throughout the 2015/16 influenza season by the epidemiologists of the headquarters and regional units of the French national public health agency. It allowed them to signal the first influenza epidemic alert in week 2016-W03, in Brittany, with 11 other regions in pre-epidemic alert. This application received positive feedback from users and was pivotal for coordinating surveillance across the agency’s regional units.

Universal or targeted approach to prevent the transmission of extended-spectrum beta-lactamase-producing Enterobacteriaceae in intensive care units: a cost-effectiveness analysis

OBJECTIVE

Several control strategies have been used to limit the transmission of multidrug-resistant organisms in hospitals. However, their implementation is expensive and effectiveness of interventions for the control of extended-spectrum beta-lactamase-producing Enterobacteriaceae (ESBL-PE) spread is controversial. Here, we aim to assess the cost-effectiveness of hospital-based strategies to prevent ESBL-PE transmission and infections.

DESIGN

Cost-effectiveness analysis based on dynamic, stochastic transmission model over a 1-year time horizon.

PATIENTS AND SETTING

Patients hospitalised in a hypothetical 10-bed intensive care unit (ICU) in a high-income country.

INTERVENTIONS

Base case scenario compared with (1) universal strategies (eg, improvement of hand hygiene (HH) among healthcare workers, antibiotic stewardship), (2) targeted strategies (eg, screening of patient for ESBL-PE at ICU admission and contact precautions or cohorting of carriers) and (3) mixed strategies (eg, targeted approaches combined with antibiotic stewardship).

MAIN OUTCOMES AND MEASURES

Cases of ESBL-PE transmission, infections, cost of intervention, cost of infections, incremental cost per infection avoided.

RESULTS

In the base case scenario, 15 transmissions and five infections due to ESBL-PE occurred per 100 ICU admissions, representing a mean cost of €94 792. All control strategies improved health outcomes and reduced costs associated with ESBL-PE infections. The overall costs (cost of intervention and infections) were the lowest for HH compliance improvement from 55%/60% before/after contact with a patient to 80%/80%.

CONCLUSIONS

Improved compliance with HH was the most cost-saving strategy to prevent the transmission of ESBL-PE. Antibiotic stewardship was not cost-effective. However, adding antibiotic restriction strategy to HH or screening and cohorting strategies slightly improved their effectiveness and may be worthy of consideration by decision-makers.

Costs associated with implementation of a strict policy for controlling spread of highly resistant microorganisms in France

OBJECTIVE

To assess costs associated with implementation of a strict 'search and isolate' strategy for controlling highly drug-resistant organisms (HDRO).

DESIGN

Review of data from 2-year prospective surveillance (01/2012 to 12/2013) of HDRO.

SETTING

Three university hospitals located in northern Paris.

METHODS

Episodes were defined as single cases or outbreaks of glycopeptide-resistant enterococci (GRE) or carbapenemase-producing Enterobacteriacae (CPE) colonisation. Costs were related to staff reinforcement, costs of screening cultures, contact precautions and interruption of new admissions. Univariate analysis, along with simple and multiple linear regression analyses, was conducted to determine variables associated with cost of HDRO management.

RESULTS

Overall, 41 consecutive episodes were included, 28 single cases and 13 outbreaks. The cost (mean ± SD) associated with management of a single case identified within and/or 48 h after admission was €4443 ± 11,552 and €11,445 ± 15,743, respectively (p<0.01). In an outbreak, the total cost varied from €14,864 ± 17,734 for an episode with one secondary case (€7432 ± 8867 per case) to €136,525 ± 151,231 (€12,845 ± 5129 per case) when more than one secondary case occurred. In episodes of single cases, contact precautions and microbiological analyses represented 51% and 30% of overall cost, respectively. In outbreaks, cost related to interruption of new admissions represented 77-94% of total costs, and had the greatest financial impact (R(2)=0.98, p<0.01).

CONCLUSIONS

In HDRO episodes occurring at three university hospitals, interruption of new admissions constituted the most costly measure in an outbreak situation.

Optimizing the precision of case fatality ratio estimates under the surveillance pyramid approach

In the management of emerging infectious disease epidemics, precise and accurate estimation of severity indices, such as the probability of death after developing symptoms—the symptomatic case fatality ratio (sCFR)—is essential. Estimation of the sCFR may require merging data gathered through different surveillance systems and surveys. Since different surveillance strategies provide different levels of precision and accuracy, there is need for a theory to help investigators select the strategy that maximizes these properties. Here, we study the precision of sCFR estimators that combine data from several levels of the severity pyramid. We derive a formula for the standard error, which helps us find the estimator with the best precision given fixed resources. We further propose rules of thumb for guiding the choice of strategy: For example, should surveillance of a particular severity level be started? Which level should be preferred? We derive a formula for the optimal allocation of resources between chosen surveillance levels and provide a simple approximation that can be used in thinking more heuristically about planning surveillance. We illustrate these concepts with numerical examples corresponding to 3 influenza pandemic scenarios. Finally, we review the equally important issue of accuracy.

Assessment of the Middle East respiratory syndrome coronavirus (MERS-CoV) epidemic in the Middle East and risk of international spread using a novel maximum likelihood analysis approach

The emergence of the novel Middle East (ME) respiratory syndrome coronavirus (MERS-CoV) has raised global public health concerns regarding the current situation and its future evolution. Here we propose an integrative maximum likelihood analysis of both cluster data in the ME and importations in a set of European countries to assess the transmission scenario and incidence of sporadic infections. Our approach is based on a spatial-transmission model integrating mobility data worldwide and allows for variations in the zoonotic/environmental transmission and under-ascertainment. Maximum likelihood estimates for the ME, considering outbreak data up to 31 August 2013, indicate the occurrence of a subcritical epidemic with a reproductive number R of 0.50 (95% confidence interval (CI): 0.30-0.77) associated with a daily rate of sporadic introductions psp of 0.28 (95% CI: 0.12-0.85). Infections in the ME appear to be mainly dominated by zoonotic/environmental transmissions, with possible under-ascertainment (ratio of estimated to observed (0.116) sporadic cases equal to 2.41, 95% CI: 1.03-7.32). No time evolution of the situation emerges. Analyses of flight passenger data from ME countries indicate areas at high risk of importation. While dismissing an immediate threat for global health security, this analysis provides a baseline scenario for future reference and updates, suggests reinforced surveillance to limit under-ascertainment, and calls for alertness in high importation risk areas worldwide.

A method to assess seasonality of urinary tract infections based on medication sales and google trends

BACKGROUND

Despite the fact that urinary tract infection (UTI) is a very frequent disease, little is known about its seasonality in the community.

METHODS AND FINDINGS

To estimate seasonality of UTI using multiple time series constructed with available proxies of UTI. Eight time series based on two databases were used: sales of urinary antibacterial medications reported by a panel of pharmacy stores in France between 2000 and 2012, and search trends on the Google search engine for UTI-related terms between 2004 and 2012 in France, Germany, Italy, the USA, China, Australia and Brazil. Differences between summers and winters were statistically assessed with the Mann-Whitney test. We evaluated seasonality by applying the Harmonics Product Spectrum on Fast Fourier Transform. Seven time series out of eight displayed a significant increase in medication sales or web searches in the summer compared to the winter, ranging from 8% to 20%. The eight time series displayed a periodicity of one year. Annual increases were seen in the summer for UTI drug sales in France and Google searches in France, the USA, Germany, Italy, and China. Increases occurred in the austral summer for Google searches in Brazil and Australia.

CONCLUSIONS

An annual seasonality of UTIs was evidenced in seven different countries, with peaks during the summer.

Age distribution of influenza like illness cases during post-pandemic A(H3N2): comparison with the twelve previous seasons, in France

In France, the 2011–2012 influenza epidemic was characterized by the circulation of antigenically drifted influenza A(H3N2) viruses and by an increased disease severity and mortality among the elderly, with respect to the A(H1N1)pdm09 pandemic and post-pandemic outbreaks. Whether the epidemiology of influenza in France differed between the 2011–2012 epidemic and the previous outbreaks is unclear. Here, we analyse the age distribution of influenza like illness (ILI) cases attended in general practice during the 2011–2012 epidemic, and compare it with that of the twelve previous epidemic seasons. Influenza like illness data were obtained through a nationwide surveillance system based on sentinel general practitioners. Vaccine effectiveness was also estimated. The estimated number of ILI cases attended in general practice during the 2011–2012 was lower than that of the past twelve epidemics. The age distribution was characteristic of previous A(H3N2)-dominated outbreaks: school-age children were relatively spared compared to epidemics (co-)dominated by A(H1N1) and/or B viruses (including the 2009 pandemic and post-pandemic outbreaks), while the proportion of adults over 30 year-old was higher. The estimated vaccine effectiveness (54%, 95% CI (48, 60)) was in the lower range for A(H3N2) epidemics. In conclusion, the age distribution of ILI cases attended in general practice seems to be not different between the A(H3N2) pre-pandemic and post-pandemic epidemics. Future researches including a more important number of ILI epidemics and confirmed virological data of influenza and other respiratory pathogens are necessary to confirm these results.

Hospitalization of influenza-like illness patients recommended by general practitioners in France between 1997 and 2010

Please cite this paper as: Pelat et al. (2012) Hospitalization of influenza‐like illness patients recommended by general practitioners in France between 1997 and 2010. Influenza and Other Respiratory Viruses DOI: 10.1111/j.1750‐2659.2012.00356.x.

Background  The case–hospitalization ratio (CHR) is a key quantity for the management of emerging pathogens such as pandemic influenza. Yet, few running surveillance systems prospectively monitor the CHR during influenza epidemics. Here, we analyze the proportion of recommended hospitalizations (PRH) among influenza‐like illness (ILI) patients attended in general practice in France and compare the PRH observed during the 2009–2010 A(H1N1) pandemic with the one of the twelve previous seasons.

Methods  ILI cases were recorded by general practitioners (GPs) involved in surveillance, who indicated for each case whether they recommended hospitalization. We stratify the analysis by age, sex, and viral subtype. We investigate the reasons why GPs recommended hospitalization and the presence of risk factors for pandemic A(H1N1) complications.

Results  The average PRH over the seasons 1997–1998 to 2008–2009 was 3·4‰ (3–3·9). It was three times higher during the 2009–2010 pandemic than during seasonal influenza epidemics (OR = 2·89, 95% CI: 2·28–3·64). The highest increase was among 20–39‐year‐old women: OR = 11·8 (5·04–29·59). Overall, the principal reasons for recommending hospitalization were “respiratory problems” and “bad general condition.” However, during the pandemic, “age” (mainly associated with infants), “pregnancy,” and “diagnostic” became more frequent than before (P < 0·001). Finally, pregnancy was the reported risk factor for pandemic A(H1N1) complications that had the largest impact on hospitalization recommendation during the pandemic (OR = 38·62, P < 0·001).

Conclusion  Easily implemented in surveillance systems, this protocol has the potential to reveal changes in hospitalization recommendation by GPs. Moreover, if the right data are collected alongside, it could give timely insights into epidemic severity.

The Chikungunya epidemic on La Réunion Island in 2005-2006: a cost-of-illness study

BACKGROUND

This study was conducted to assess the impact of chikungunya on health costs during the epidemic that occurred on La Réunion in 2005-2006.

METHODOLOGY/PRINCIPAL FINDINGS

From data collected from health agencies, the additional costs incurred by chikungunya in terms of consultations, drug consumption and absence from work were determined by a comparison with the expected costs outside the epidemic period. The cost of hospitalization was estimated from data provided by the national hospitalization database for short-term care by considering all hospital stays in which the ICD-10 code A92.0 appeared. A cost-of-illness study was conducted from the perspective of the third-party payer. Direct medical costs per outpatient and inpatient case were evaluated. The costs were estimated in Euros at 2006 values. Additional reimbursements for consultations with general practitioners and drugs were estimated as € 12.4 million (range: € 7.7 million-€ 17.1 million) and € 5 million (€ 1.9 million-€ 8.1 million), respectively, while the cost of hospitalization for chikungunya was estimated to be € 8.5 million (€ 5.8 million-€ 8.7 million). Productivity costs were estimated as € 17.4 million (€ 6 million-€ 28.9 million). The medical cost of the chikungunya epidemic was estimated as € 43.9 million, 60% due to direct medical costs and 40% to indirect costs (€ 26.5 million and € 17.4 million, respectively). The direct medical cost was assessed as € 90 for each outpatient and € 2,000 for each inpatient.

CONCLUSIONS/SIGNIFICANCE

The medical management of chikungunya during the epidemic on La Réunion Island was associated with an important economic burden. The estimated cost of the reported disease can be used to evaluate the cost/efficacy and cost/benefit ratios for prevention and control programmes of emerging arboviruses.

Field effectiveness of pandemic and 2009-2010 seasonal vaccines against 2009-2010 A(H1N1) influenza: estimations from surveillance data in France

BACKGROUND

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.

METHODOLOGY AND PRINCIPAL FINDINGS

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.

CONCLUSIONS

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.

A method for selecting and monitoring medication sales for surveillance of gastroenteritis

PURPOSE

Monitoring appropriate categories of medication sales can provide early warning of certain disease outbreaks. This paper presents a methodology for choosing and monitoring medication sales relevant for the surveillance of gastroenteritis and assesses the operational characteristics of the selected medications for early warning.

METHODS

Acute diarrhoea incidences in mainland France were obtained from the Sentinelles network surveillance system for the period 2000-2009. Medication sales grouped by therapeutic classes were obtained on the same period. Hierarchical clustering was used to select therapeutic classes correlating with disease incidence over the period. Alert thresholds were defined for the selected therapeutic classes. Single and multiple voter algorithms were investigated for outbreak detection based on sales crossing the thresholds. Sensitivity and specificity were calculated respective to known outbreaks periods.

RESULTS

Four therapeutic classes were found to cluster with acute diarrhoea incidence. The therapeutic class other antiemetic and antinauseants had the best sensitivity (100%) and timeliness (1.625 weeks before official alerts), for a false alarm rate of 5%. Multiple voter algorithm was the most efficient with the rule: 'Emit an outbreak alert when at least three therapeutic classes are over their threshold' (sensitivity 100%, specificity 95%, timeliness 1.750 weeks before official alerts).

CONCLUSIONS

The presented method allowed selection of relevant therapeutic classes for surveillance of a specific condition. Multiple voter algorithm based on several therapeutic classes performed slightly better than the best therapeutic class alone, while improving robustness against abrupt changes occurring in a single therapeutic class.

Short-term effects of airborne pollens on asthma attacks as seen by general practitioners in the Greater Paris area, 2003-2007

AIMS

To investigate for the first time the short-term effects of airborne pollen counts on general practitioner (GP) consultations for asthma attacks in the Greater Paris area between 2003-2007.

METHODS

Counts were available for common pollens (Betula, Cupressa, Fraxinus and Poaceae). Weekly data on GP visits for asthma attacks were obtained from the French GP Sentinel Network. A quasi-Poisson regression with generalised additive models was implemented. Short-term effects of pollen counts were assessed using single and multi-pollen models after adjustment for air pollution and influenza.

RESULTS

A mean weekly incidence rate of 25.4 cases of asthma attacks per 100,000 inhabitants was estimated during the study period. The strongest significant association between asthma attacks and pollen counts was registered for grass (Poaceae) in the same week of asthma attacks, with a slight reduction of the effect observed in the multi-pollen model. Adjusted relative risk for Poaceae was 1.54 (95% CI: 1.33-1.79) with an inter-quartile range increase of 17.6 grains/m3 during the pollen season.

CONCLUSIONS

For the first time, a significant short-term association was observed between Poaceae pollen counts and consultations for asthma attacks as seen by GPs. These findings need to be confirmed by more consistent time-series and investigations on a daily basis.

Reducing gastroenteritis occurrences and their consequences in elementary schools with alcohol-based hand sanitizers

BACKGROUND

Schools are a source of epidemic seasonal dissemination-in particular gastroenteritis among children and the general population. We assessed the impact of an alcohol-based sanitizer on gastroenteritis and its subsequent consequences.

METHODS

A study was conducted in 2 primary schools over a 17-week period, before and throughout the seasonal gastroenteritis period. The intervention, under strict teacher supervision and in a realistic and long lasting manner, consisted of 1 school rubbing an alcohol-based sanitizer into the hands of the school children. The primary outcome was the proportion of children without any occurrence of gastroenteritis during the study period both in the treated group and the control group, which were 2 separate schools. A Cox proportional hazards model was used to assess the hazard ratio. Secondary outcomes were the number of gastroenteritis episodes, doctor appointments, absenteeism, and working days lost by a parent.

RESULTS

Four thousand six hundred fifty-four weekly questionnaires were collected. One hundred fifty-five children presented with at least 1 occurrence of gastroenteritis during the study period: 64 of 259 in the treatment group and 91 of 217 in the control group (χ2 = 16.4, P < 0.0001). The instantaneous risk of primary infection, at any time of the study, for children receiving the treatment was multiplied by 0.52 (95% CI: [0.37,0.71]) compared with children not receiving the treatment. The average number of gastroenteritis episodes was 0.31 in the treatment group and 0.53 in the control group (P < 0.001).

CONCLUSIONS

Systematic and controlled use of alcohol-based sanitizers during the epidemic season could significantly reduce the incidence of gastroenteritis in primary school children.

Planning for the next influenza H1N1 season: a modelling study

Background

The level of herd immunity before and after the first 2009 pandemic season is not precisely known, and predicting the shape of the next pandemic H1N1 season is a difficult challenge.

Methods

This was a modelling study based on data on medical visits for influenza-like illness collected by the French General Practitioner Sentinel network, as well as pandemic H1N1 vaccination coverage rates, and an individual-centred model devoted to influenza. We estimated infection attack rates during the first 2009 pandemic H1N1 season in France, and the rates of pre- and post-exposure immunity. We then simulated various scenarios in which a pandemic influenza H1N1 virus would be reintroduced into a population with varying levels of protective cross-immunity, and considered the impact of extending influenza vaccination.

Results

During the first pandemic season in France, the proportion of infected persons was 18.1% overall, 38.3% among children, 14.8% among younger adults and 1.6% among the elderly. The rates of pre-exposure immunity required to fit data collected during the first pandemic season were 36% in younger adults and 85% in the elderly. We estimated that the rate of post-exposure immunity was 57.3% (95% Confidence Interval (95%CI) 49.6%-65.0%) overall, 44.6% (95%CI 35.5%-53.6%) in children, 53.8% (95%CI 44.5%-63.1%) in younger adults, and 87.4% (95%CI 82.0%-92.8%) in the elderly.

The shape of a second season would depend on the degree of persistent protective cross-immunity to descendants of the 2009 H1N1 viruses. A cross-protection rate of 70% would imply that only a small proportion of the population would be affected. With a cross-protection rate of 50%, the second season would have a disease burden similar to the first, while vaccination of 50% of the entire population, in addition to the population vaccinated during the first pandemic season, would halve this burden. With a cross-protection rate of 30%, the second season could be more substantial, and vaccination would not provide a significant benefit.

Conclusions

These model-based findings should help to prepare for a second pandemic season, and highlight the need for studies of the different components of immune protection.

Early estimates of 2009 pandemic influenza A(H1N1) virus activity in general practice in France: incidence of influenza-like illness and age distribution of reported cases

In the end of August 2009, an unusually elevated level of influenza-like illness (ILI) activity was reported to the French Sentinel Network. We quantified the observed excess in ILI cases in France during summer 2009 and characterised age patterns in reported cases. An excess of cases has been observed since 5 July, with a time increasing trend. The cumulated estimated excess number of ILI cases was 269,935 [179,585; 316,512], corresponding to 0.5% French population over the period. Compared to the same period in the past years, relative cumulated incidence was greater among young subjects and lower among subjects over 65 years old. Compared to past epidemics, the relative cumulated incidence was greater in children less than 5 years old. This excess of cases may reflect the current spread of the A(H1N1) virus in France, subject to the following limitations: estimates were based on clinical cases consulting a GP; large media coverage may have led to a non specific increase in consultation rates.

Mortality burden of the 1918-1919 influenza pandemic in Europe

Background  The origin and estimated death toll of the 1918–1919 epidemic are still debated. Europe, one of the candidate sites for pandemic emergence, has detailed pandemic mortality information.

Objective  To determine the mortality impact of the 1918 pandemic in 14 European countries, accounting for approximately three‐quarters of the European population (250 million in 1918).

Methods  We analyzed monthly all‐cause civilian mortality rates in the 14 countries, accounting for approximately three‐quarters of the European population (250 million in 1918). A periodic regression model was applied to estimate excess mortality from 1906 to 1922. Using the 1906–1917 data as a training set, the method provided a non‐epidemic baseline for 1918–1922. Excess mortality was the mortality observed above this baseline. It represents the upper bound of the mortality attributable to the flu pandemic.

Results  Our analysis suggests that 2·64 million excess deaths occurred in Europe during the period when Spanish flu was circulating. The method provided space variation of the excess mortality: the highest and lowest cumulative excess/predicted mortality ratios were observed in Italy (+172%) and Finland (+33%). Excess‐death curves showed high synchrony in 1918–1919 with peak mortality occurring in all countries during a 2‐month window (Oct–Nov 1918).

Conclusions  During the Spanish flu, the excess mortality was 1·1% of the European population. Our study highlights the synchrony of the mortality waves in the different countries, which pleads against a European origin of the pandemic, as was sometimes hypothesized.

Online detection and quantification of epidemics

BACKGROUND

Time series data are increasingly available in health care, especially for the purpose of disease surveillance. The analysis of such data has long used periodic regression models to detect outbreaks and estimate epidemic burdens. However, implementation of the method may be difficult due to lack of statistical expertise. No dedicated tool is available to perform and guide analyses.

RESULTS

We developed an online computer application allowing analysis of epidemiologic time series. The system is available online at http://www.u707.jussieu.fr/periodic_regression/. The data is assumed to consist of a periodic baseline level and irregularly occurring epidemics. The program allows estimating the periodic baseline level and associated upper forecast limit. The latter defines a threshold for epidemic detection. The burden of an epidemic is defined as the cumulated signal in excess of the baseline estimate. The user is guided through the necessary choices for analysis. We illustrate the usage of the online epidemic analysis tool with two examples: the retrospective detection and quantification of excess pneumonia and influenza (P&I) mortality, and the prospective surveillance of gastrointestinal disease (diarrhoea).

CONCLUSION

The online application allows easy detection of special events in an epidemiologic time series and quantification of excess mortality/morbidity as a change from baseline. It should be a valuable tool for field and public health practitioners.

Complex segregation analysis accounting for GxE of bone mineral density in European pedigrees selected through a male proband with low BMD

Osteoporosis is a common multifactorial disorder characterized by low bone mass (BMD) and high susceptibility to low-trauma fractures. Family and twin studies have found a strong genetic component in the determination of BMD, but the mode of inheritance of this trait is not yet fully understood. BMD is a complex trait whose expression is confounded by environmental influences and polygenic inheritance. Detection of potential gene-environment interactions is of great interest in the determination of bone health status. Here we have conducted segregation analyses, using the regressive class D models, in a sample of 100 European pedigrees (NEMO) with 713 subjects (524 measured for phenotypes) identified via a male with low BMD values at either the Lumbar Spine or the Femoral Neck. Segregation analyses were conducted on the residuals of LS-BMD and FN-BMD adjusted for gender, age and BMI. We tested for gene-covariate (GxE) interactions, and investigated the impact of significant GxE interactions on segregation results. Without GxE a major effect was found to be marginally significant in LS-BMD and highly significant in FN-BMD. For both traits the Mendelian hypothesis was rejected. Significant Age x gene and BMI x gene interactions were revealed. Accounting for GxE increased statistical evidence for a major factor in LS-BMD, and improved the fit of the data to the Mendelian transmission model for both traits. The best fitting models suggested a codominant major gene accounting for 45% (LS-BMD) and 44% (FN-BMD) of the adjusted BMDs. However, substantial residual correlations were also found, and these remained highly significant after accounting for the major gene.