Social conformism and confidence in systems as additional psychological antecedents of vaccination: a survey to explain intention for COVID-19 vaccination among healthcare and welfare sector workers, France, December 2020 to February 2021.

BackgroundThe start of the COVID-19 vaccination campaign among French healthcare and welfare sector workers in January 2021 offered an opportunity to study psychological antecedents of vaccination in this group.AimWe explored whether knowledge and attitude items related to social conformism and confidence in systems contributed to explaining intention for COVID-19 vaccination.MethodsWe developed a knowledge and attitude questionnaire with 30 items related to five established and two hypothetical psychological antecedents of vaccination (KA-7C). The online questionnaire was distributed from 18 December 2020 to 1 February 2021 through chain-referral via professional networks, yielding a convenience sample. We used multivariable logistic regression to explore the associations of individual and grouped KA-7C items with COVID-19 vaccine intention.ResultsAmong 5,234 participants, the vaccine intention model fit (pseudo R-squared values) increased slightly but significantly from 0.62 to 0.65 when adding social conformism and confidence in systems items. Intention to vaccinate was associated with the majority opinion among family and friends (OR: 11.57; 95% confidence interval (CI): 4.51-29.67) and a positive perception of employer's encouragement to get vaccinated (vs negative; OR: 6.41; 95% CI: 3.36-12.22). The strongest association of a knowledge item was identifying the statement 'Some stages of vaccine development (testing) have been skipped because of the epidemic emergency.' as false (OR: 2.36; 95% CI: 1.73-3.22).ConclusionThe results suggest that social conformism and confidence in systems are distinct antecedents of vaccination among healthcare and welfare workers, which should be taken into account in vaccine promotion.

Évaluation de supports de communication nationaux sur la COVID-19 : recours à une méthode mixte.

INTRODUCTION: The challenges of communicating with the population during a health crisis are multiple, with the ultimate objective of getting as many people as possible to apply preventive measures. AIM: The objective of this article is to present the results of an evaluation of the communication contents on COVID-19 prevention broadcast by Santé publique France (the national public health agency) on March 2020, for the general population. Two studies, one quantitative and one qualitative, were carried out during the first lockdown. The "Coronavirus Alert" communication campaign then included four media contents (spots and posters) describing health protective behaviors and signs of the disease. RESULTS: Recall of the campaign was particularly high, with nine in ten spontaneously citing messages from the campaign. Over 90% found it easy to understand and useful, although 20% found it induced anxiety. The declared impact on behavior was also very high, with 97% of people affirming to be encouraged by the media contents to implement health protective behaviors. There was, however, lower adherence to the campaign among men and low-income people.The qualitative study clarified some of the results: the clarity of the materials was attributed to the pictograms illustrating the health protective behaviors, and the tone of the spots was judged appropriate to the seriousness of the health situation. CONCLUSION: These studies highlight significant exposure to the supports tested and a positive perception of them. Their lessons were useful in continuing the dissemination of the health protection tools produced by Santé publique France.

Evolving heat waves characteristics challenge heat warning systems and prevention plans.

This paper analyses how recent trends in heat waves impact heat warning systems. We performed a retrospective analysis of the challenges faced by the French heat prevention plan since 2004. We described trends based on the environmental and health data collected each summer by the French heat warning system and prevention plan. Major evolutions of the system were tracked based on the evaluations organized each autumn with the stakeholders of the prevention plan. Excess deaths numbering 8000 were observed during heat waves between 2004 and 2019, 71% of these between 2015 and 2019. We observed major changes in the characteristics, frequency and the geographical spread of heat waves since 2015. Feedbacks led to several updates of the warning system such as the extension of the surveillance period. They also revealed that risk perception remained limited among the population and the stakeholders. The sharp increase in the number of heat warnings issued per year since 2015 challenges the acceptability of the heat warnings. Recent heat waves without historical equivalent interfere with the development of evidence-based prevention strategies. The growing public health impacts heat waves emphasize the urgent need to act to adapt the population, at different levels of intervention, from individual comportments to structural modifications. A specific attention should be given to increase the resources allocated to the evaluation and the management of heat-related risks, especially considering the needs to catch with the rapid rhythm of the changing climate.

Neuraminidase Inhibitors and Hospital Length of Stay: A Meta-analysis of Individual Participant Data to Determine Treatment Effectiveness Among Patients Hospitalized With Nonfatal 2009 Pandemic Influenza A(H1N1) Virus Infection.

BACKGROUND: The effect of neuraminidase inhibitor (NAI) treatment on length of stay (LoS) in patients hospitalized with influenza is unclear. METHODS: We conducted a one-stage individual participant data (IPD) meta-analysis exploring the association between NAI treatment and LoS in patients hospitalized with 2009 influenza A(H1N1) virus (A[H1N1]pdm09) infection. Using mixed-effects negative binomial regression and adjusting for the propensity to receive NAI, antibiotic, and corticosteroid treatment, we calculated incidence rate ratios (IRRs) and 95% confidence intervals (CIs). Patients with a LoS of <1 day and those who died while hospitalized were excluded. RESULTS: We analyzed data on 18 309 patients from 70 clinical centers. After adjustment, NAI treatment initiated at hospitalization was associated with a 19% reduction in the LoS among patients with clinically suspected or laboratory-confirmed influenza A(H1N1)pdm09 infection (IRR, 0.81; 95% CI, .78-.85), compared with later or no initiation of NAI treatment. Similar statistically significant associations were seen in all clinical subgroups. NAI treatment (at any time), compared with no NAI treatment, and NAI treatment initiated <2 days after symptom onset, compared with later or no initiation of NAI treatment, showed mixed patterns of association with the LoS. CONCLUSIONS: When patients hospitalized with influenza are treated with NAIs, treatment initiated on admission, regardless of time since symptom onset, is associated with a reduced LoS, compared with later or no initiation of treatment.

Assessment of the impact of the extension of vaccination mandates on vaccine coverage after 1 year, France, 2019.

One year after the extension of the childhood vaccination mandates to the 11 routine vaccinations for children under 2 years old, we estimated vaccination coverage through vaccine reimbursement data. Coverage for children born in 2018 has notably increased. Moreover, vaccine coverage for children and for vaccines not concerned by the law have also shown an increasing trend, supporting a positive impact of the ongoing communication strategy on vaccination, beyond the extension of vaccination mandates.

The potential value of crowdsourced surveillance systems in supplementing sentinel influenza networks: the case of France.

IntroductionParticipatory surveillance systems provide rich crowdsourced data, profiling individuals and their health status at a given time. We explored the usefulness of data from GrippeNet.fr, a participatory surveillance system, to estimate influenza-related illness incidence in France. Methods: GrippeNet.fr is an online cohort since 2012 averaging ca. 5,000 weekly participants reporting signs/symptoms suggestive of influenza. GrippeNet.fr has flexible criteria to define influenza-related illness. Different case definitions based on reported signs/symptoms and inclusions of criteria accounting for individuals' reporting and participation were used to produce influenza-related illness incidence estimates, which were compared to those from sentinel networks. We focused on the 2012/13 and 2013/14 seasons when two sentinel networks, monitoring influenza-like-illness (ILI) and acute respiratory infections (ARI) existed in France. Results: GrippeNet.fr incidence estimates agreed well with official temporal trends, with a higher accuracy for ARI than ILI. The influenza epidemic peak was often anticipated by one week, despite irregular participation of individuals. The European Centre for Disease Prevention and Control ILI definition, commonly used by participatory surveillance in Europe, performed better in tracking ARI than ILI when applied to GrippeNet.fr data. Conclusion: Evaluation of the epidemic intensity from crowdsourced data requires epidemic and intensity threshold estimations from several consecutive seasons. The study provides a standardised analytical framework for crowdsourced surveillance showing high sensitivity in detecting influenza-related changes in the population. It contributes to improve the comparability of epidemics across seasons and with sentinel systems. In France, GrippeNet.fr may supplement the ILI sentinel network after ARI surveillance discontinuation in 2014.

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.

Participatory Syndromic Surveillance of Influenza in Europe.

The growth of digital communication technologies for public health is offering an unconventional means to engage the general public in monitoring community health. Here we present Influenzanet, a participatory system for the syndromic surveillance of influenza-like illness (ILI) in Europe. Through standardized online surveys, the system collects detailed profile information and self-reported symptoms volunteered by participants resident in the Influenzanet countries. Established in 2009, it now includes 10 countries representing more than half of the 28 member states of the European Union population. The experience of 7 influenza seasons illustrates how Influenzanet has become an adjunct to existing ILI surveillance networks, offering coherence across countries, inclusion of nonmedically attended ILI, flexibility in case definition, and facilitating individual-level epidemiological analyses generally not possible in standard systems. Having the sensitivity to timely detect substantial changes in population health, Influenzanet has the potential to become a viable instrument for a wide variety of applications in public health preparedness and control.

First nationwide web-based surveillance system for influenza-like illness in pregnant women: participation and representativeness of the French G-GrippeNet cohort.

BACKGROUND: Pregnancy is a risk factor for severe influenza resulting in increased risks of hospitalisation and death in mothers and their new-borns. Our objective was to assess the representativeness and participation of French women to a new web-based collaborative tool for data collection and monitoring of Influenza Like Illness (ILI) during pregnancy. METHODS: During the 2014/2015 influenza season, pregnant women living in metropolitan France were enrolled through a web platform ( https://www.grippenet.fr/). Then throughout the season, participants were asked to report, on a weekly basis, if they had experienced symptoms of ILI. Representativeness was assessed by comparing the characteristics of participants to those of the French National Perinatal Survey. For each participant, the participation rate was the number of weekly questionnaires completed, divided by the length of follow-up (in weeks). Predictors of active participation (participation rate >15%) were assessed by multivariate logistic regression. RESULTS: A total of 153 women were enrolled. Participants were older (mean age 34 years vs. 29 years) and more highly educated (high school level 89% versus 52%) than the general population of pregnant women in France, but the sample did not differ on pregnancy-related characteristics (parity, history of hospitalisation during a previous pregnancy). The median rate of participation was high (78%, interquartile range: 34-96). Higher educational level and participation to a previous GrippeNet.fr season were associated with active participation. CONCLUSION: Despite small sample size and lack of representativeness, the retention rate was high, suggesting that pregnant women are prone to adhere to a longitudinal follow-up of their health status via the Internet.

Intensive care unit surveillance of influenza infection in France: the 2009/10 pandemic and the three subsequent seasons.

During the 2009/10 pandemic, a national surveillance system for severe influenza cases was set up in France. We present results from the system's first four years. All severe influenza cases admitted to intensive care units (ICU) were reported to the Institut de Veille Sanitaire using a standardised form: data on demographics, immunisation and virological status, risk factors, severity (e.g. acute respiratory distress syndrome (ARDS) onset, mechanical ventilation, extracorporeal life support) and outcome. Multivariate analysis was performed to identify factors associated with ARDS and death. The number of confirmed influenza cases varied from 1,210 in 2009/10 to 321 in 2011/12. Most ICU patients were infected with A(H1N1)pdm09, except during the 2011/12 winter season when A(H3N2)-related infections predominated. Patients' characteristics varied according to the predominant strain. Based on multivariate analysis, risk factors associated with death were age ≥ 65 years, patients with any of the usual recommended indications for vaccination and clinical severity. ARDS occurred more frequently in patients who were middle-aged (36-55 years), pregnant, obese, or infected with A(H1N1)pdm09. Female sex and influenza vaccination were protective. These data confirm the persistent virulence of A(H1N1)pdm09 after the pandemic and the heterogeneity of influenza seasons, and reinforce the need for surveillance of severe influenza cases.

The representativeness of a European multi-center network for influenza-like-illness participatory surveillance.

BACKGROUND: The Internet is becoming more commonly used as a tool for disease surveillance. Similarly to other surveillance systems and to studies using online data collection, Internet-based surveillance will have biases in participation, affecting the generalizability of the results. Here we quantify the participation biases of Influenzanet, an ongoing European-wide network of Internet-based participatory surveillance systems for influenza-like-illness. METHODS: In 2011/2012 Influenzanet launched a standardized common framework for data collection applied to seven European countries. Influenzanet participants were compared to the general population of the participating countries to assess the representativeness of the sample in terms of a set of demographic, geographic, socio-economic and health indicators. RESULTS: More than 30,000 European residents registered to the system in the 2011/2012 season, and a subset of 25,481 participants were selected for this study. All age classes (10 years brackets) were represented in the cohort, including under 10 and over 70 years old. The Influenzanet population was not representative of the general population in terms of age distribution, underrepresenting the youngest and oldest age classes. The gender imbalance differed between countries. A counterbalance between gender-specific information-seeking behavior (more prominent in women) and Internet usage (with higher rates in male populations) may be at the origin of this difference. Once adjusted by demographic indicators, a similar propensity to commute was observed for each country, and the same top three transportation modes were used for six countries out of seven. Smokers were underrepresented in the majority of countries, as were individuals with diabetes; the representativeness of asthma prevalence and vaccination coverage for 65+ individuals in two successive seasons (2010/2011 and 2011/2012) varied between countries. CONCLUSIONS: Existing demographic and national datasets allowed the quantification of the participation biases of a large cohort for influenza-like-illness surveillance in the general population. Significant differences were found between Influenzanet participants and the general population. The quantified biases need to be taken into account in the analysis of Influenzanet epidemiological studies and provide indications on populations groups that should be targeted in recruitment efforts.

A conceptual framework to model social determinants of COVID-19 vaccination uptake among underserved homeless populations.

Background:  Homeless people have a higher risk of COVID-19 infection, linked to several social, economic and environmental determinants, frequent comorbidities, obstacles to exercising their constitutional social and health rights, poor medical cover, and insufficient use of the healthcare system. Data on COVID-19 vaccine uptake and its main determinants are lacking for this underserved population. Objectives:  To construct and test a conceptual framework to model structural social determinants of COVID-19 vaccine uptake among underserved homeless populations, and to test this model to identify the determinants of COVID-19 vaccine uptake on the homeless population living in two metropolitan areas in France. Methods:  We implemented a multicenter cross-sectional survey from 15/11/2021 to 22/12/2021 in homeless adults in the city of Marseille and in the greater Paris area. Persons sheltered in migrant worker hostels or in emergency social shelters, members of the COVID HOMELESS cohort study in Marseille, and Travelers living in traditional housing were all eligible. A standardized face-to-face questionnaire was administered to the participants where they lived in various languages by trained interviewers. We used structural equation modeling to analyze the structural social determinants of COVID-19 vaccine uptake, the latter defined as receiving at least one dose. Results:  The participation rate was 64 %, accounting for 3811 participants. There were three main factors associated with greater vaccine uptake: i) opportunity, which included having a personal general practitioner (ß = 0.05, p < 0.05), healthcare cover (ß = 0.05, p < 0.05), and somebody to accompany the participant for medical appointments (ß = -0.04, p < 0.05); ii) motivation, which included attitudes towards vaccination (ß = 0.55, p < 0.05), press- and poster-based information (ß = 0.03, p < 0.05), and vaccination history (ß = 0.03, p < 0.05); iii) type of housing (ß = 0.13, p < 0.05) and housing stability (ß = 0.04, p < 0.05). Conclusion:  Our results highlight that housing exclusion is a structural social determinant of COVID-19 vaccine uptake in homeless people in France. They also underline the role which opportunity and motivation play in improving uptake in this underserved homeless population.

Vaccination acceptability in the French general population and related determinants, 2000-2021.

BACKGROUND: This study describes the evolution of vaccination acceptability and associated determinants in the French general population between 2000 and 2021, and vaccinations with the highest vaccine hesitancy between 2010 and 2021. METHODS: Data were collected from the nine national 'Health Barometer' cross-sectional surveys conducted between 2000 and 2021. These surveys included French-speaking individuals aged 18-75 years old who were selected through randomly generated landline and mobile phone numbers. Participants were asked about their acceptability of vaccination in general and their vaccine hesitancy toward any particular vaccinations. Determinants of vaccination acceptability were studied using univariate and multivariate Poisson regressions. RESULTS: The proportion of persons who found vaccination acceptable in general (i.e., answering "very" or "somewhat" favourable in the survey interview) decreased from 91.1% in 2000 to 61.2% in 2010 (the latter year coinciding with the 2009 H1N1 influenza pandemic), increased in 2014 (78.8%), slightly fluctuated until 2019 (74.2%), and increased again in both 2020 (80.0%) and 2021 (82.5%) during the COVID-19 pandemic. Irrespective of the year, acceptability was higher among persons with higher incomes, those with a higher education level, and individuals not living alone. In 2021, for the first time, vaccination acceptability was higher among persons over 44 years old (versus 18-24 year-olds) and among retired persons (versus workers). The highest hesitancy rate for a vaccine was for the 2009 H1N1 influenza virus in 2010 (41% answering "somewhat" or "very" unfavourable). In 2021, the highest rate was for the COVID-19 vaccine (21%). DISCUSSION: Unlike the experience of the 2009 AH1N1 influenza pandemic, which led to a collapse in vaccination acceptability among the French general population, acceptability continued to increase during the COVID-19 pandemic. However, the pre-2010 level was not reached. Our results show a tendency towards a widening social and economic gap in terms of vaccine acceptability over time.

Predictors of Uncertainty and Unwillingness to Receive the COVID-19 Vaccine in Men Who Have Sex with Men in France.

The development of vaccines against COVID-19 has given hope to populations. Public acceptability of vaccination is a major driver in containing the disease. However, in marginalized and stigmatized populations, uncertainty and unwillingness may be a challenge. This study aimed to analyze the factors associated with uncertainty and unwillingness to vaccinate against COVID-19 in men who have sex with men (MSM) living in France. The data used came from Rapport au Sexe (ERAS) 2021, a voluntary, cross-sectional, anonymous, self-administered, online survey conducted from 26 February to 11 April 2021. Among the 15,426 respondents included in the analysis, 60.5% were willing to vaccinate (these included persons already vaccinated), 17.5% were not, and 22% were uncertain. Factors independently associated with uncertainty and unwillingness were lower education level, low health literacy level, financial hardship, being under 30 years of age, and living in a rural area. HIV-positive MSM were less likely to report vaccination uncertainty and unwillingness than HIV-negative MSM and those with unknown serostatus. Although more impacted by COVID-19, socioeconomically vulnerable MSM were the sub-group most unwilling to vaccinate. To improve acceptability of COVID-19 vaccination in MSM, policy makers and researchers must increase access to and understanding of medical information by considering the general public's health literacy when developing information sources. Moreover, a dedicated global care approach, which ensures these populations can be reached, is necessary.

Perceptions and attitudes about antibiotic resistance in the general public and general practitioners in France.

BACKGROUND: During the last 20 years, France has taken important steps to tackle antibiotic resistance. These include national awareness campaigns for the general public, and supporting changes in terms of antibiotic prescription for healthcare practitioners. To prepare the upcoming 2022/2023 campaign, we conducted two surveys to assess (1) the general public's knowledge, attitudes and behaviours regarding antibiotics and (2) the perceptions and practices of general practitioners (GPs). METHODS: Two quantitative telephone surveys were conducted using the same methodology as that used in 2010 by the National Health Insurance Authority. The first was conducted in 2019 in a national representative quota sample of 1204 persons aged over 15 years living in metropolitan France, including an over-sample of 332 parents of children aged six years or under. The second was conducted in 2020 in a national representative sample of 388 GPs. RESULTS: Twenty-seven percent of respondents reported taking antibiotics during the previous year. Sixty-five percent of GPs declared prescribing fewer antibiotics during the previous five years. However, 33% of GPs reported they often had patients who put high pressure to get antibiotics. The pressure from elderly patients, especially those with comorbidities was notable. Three percent of respondent patients reported putting often pressure on their GP. All respondents expressed total trust in their GP irrespective of whether s/he had prescribed them antibiotics. Half knew that antibiotics act only on bacteria, and 38% said they understood precisely what antibiotic resistance is. CONCLUSION: Although antibiotic use is decreasing in France, patient pressure on GPs to prescribe antibiotics is very high. GPs are key ambassadors in reducing antibiotic use. Awareness campaigns must target elderly patients in particular.

Risk factors for severe outcomes following 2009 influenza A (H1N1) infection: a global pooled analysis.

BACKGROUND: Since the start of the 2009 influenza A pandemic (H1N1pdm), the World Health Organization and its member states have gathered information to characterize the clinical severity of H1N1pdm infection and to assist policy makers to determine risk groups for targeted control measures. METHODS AND FINDINGS: Data were collected on approximately 70,000 laboratory-confirmed hospitalized H1N1pdm patients, 9,700 patients admitted to intensive care units (ICUs), and 2,500 deaths reported between 1 April 2009 and 1 January 2010 from 19 countries or administrative regions--Argentina, Australia, Canada, Chile, China, France, Germany, Hong Kong SAR, Japan, Madagascar, Mexico, The Netherlands, New Zealand, Singapore, South Africa, Spain, Thailand, the United States, and the United Kingdom--to characterize and compare the distribution of risk factors among H1N1pdm patients at three levels of severity: hospitalizations, ICU admissions, and deaths. The median age of patients increased with severity of disease. The highest per capita risk of hospitalization was among patients <5 y and 5-14 y (relative risk [RR] = 3.3 and 3.2, respectively, compared to the general population), whereas the highest risk of death per capita was in the age groups 50-64 y and ≥65 y (RR = 1.5 and 1.6, respectively, compared to the general population). Similarly, the ratio of H1N1pdm deaths to hospitalizations increased with age and was the highest in the ≥65-y-old age group, indicating that while infection rates have been observed to be very low in the oldest age group, risk of death in those over the age of 64 y who became infected was higher than in younger groups. The proportion of H1N1pdm patients with one or more reported chronic conditions increased with severity (median = 31.1%, 52.3%, and 61.8% of hospitalized, ICU-admitted, and fatal H1N1pdm cases, respectively). With the exception of the risk factors asthma, pregnancy, and obesity, the proportion of patients with each risk factor increased with severity level. For all levels of severity, pregnant women in their third trimester consistently accounted for the majority of the total of pregnant women. Our findings suggest that morbid obesity might be a risk factor for ICU admission and fatal outcome (RR = 36.3). CONCLUSIONS: Our results demonstrate that risk factors for severe H1N1pdm infection are similar to those for seasonal influenza, with some notable differences, such as younger age groups and obesity, and reinforce the need to identify and protect groups at highest risk of severe outcomes. Please see later in the article for the Editors' Summary.

Nationwide surveillance of 18 respiratory viruses in patients with influenza-like illnesses: a pilot feasibility study in the French Sentinel Network.

The aim of the present study was to test the feasibility of integrating the diagnosis of 18 respiratory viruses into clinical surveillance of influenza-like illness using a PCR-DNA microarray detection assay. The study took place in the French Sentinel Network, a nationwide surveillance network of General Practitioners (GPs) representative of French GPs in terms age, location, and type of practice (urban/rural). Three virological laboratories also participated in the study. The study was planned for 5 weeks from January 25, 2010 to February 27, 2010. A subset of 150 Sentinel GPs, located in mainland France, was enrolled to collect clinical data and nasopharyngeal samples from every first patient of the week having a medical visit for influenza-like illness defined as a sudden fever of 39°C or more with respiratory symptoms and myalgia. Sixty-three GPs (42%) collected 103 samples while 87 GPs (58%) did not. GPs did not differ with respect to their age, gender, urban/rural distribution, or years of inscription in the Sentinel Network. Patients included were of a similar age and had similar vaccination characteristics, but were more frequently men than influenza-like illness patients reported to the network during the study period. Sixty-one viruses were detected from 56 of 96 (58%) interpretable samples. The respiratory viruses detected most frequently were metapneumovirus and respiratory syncytial virus. This study showed that virological diagnosis of 18 respiratory viruses can be combined with surveillance of clinical influenza-like illness in general practice. Although feasibility has not been demonstrated yet, it will be evaluated over the winter of 2010-2011.

Optimising HPV vaccination communication to adolescents: A discrete choice experiment.

BACKGROUND: Human Papillomavirus (HPV) vaccine coverage in France is below 30%, despite proven effectiveness against HPV infections and (pre-)cancerous cervical lesions. To optimise vaccine promotion among adolescents, we used a discrete choice experiment (DCE) to identify optimal statements regarding a vaccination programme, including vaccine characteristics. METHODS: Girls and boys enrolled in the last two years of five middle schools in three French regions (aged 13-15 years) participated in an in-class cross-sectional self-administered internet-based study. In ten hypothetical scenarios, participants decided for or against signing up for a school-based vaccination campaign against an unnamed disease. Scenarios included different levels of four attributes: the type of vaccine-preventable disease, communication on vaccine safety, potential for indirect protection, and information on vaccine uptake among peers. One scenario was repeated with an added mention of sexual transmission. RESULTS: The 1,458 participating adolescents (estimated response rate: 89.4%) theoretically accepted vaccination in 80.1% of scenarios. All attributes significantly impacted theoretical vaccine acceptance. Compared to a febrile respiratory disease, protection against cancer was motivating (odds ratio (OR) 1.29 [95%-CI 1.09-1.52]), but not against genital warts (OR 0.91 [0.78-1.06]). Compared to risk negation ("vaccine does not provoke serious side effects"), a reference to a positive benefit-risk balance despite a confirmed side effect was strongly dissuasive (OR 0.30 [0.24-0.36]), while reference to ongoing international pharmacovigilance without any scientifically confirmed effect was not significantly dissuasive (OR 0.86 [0.71-1.04]). The potential for indirect protection motivated acceptance among girls but not boys (potential for eliminating the disease compared to no indirect protection, OR 1.57 [1.25-1.96]). Compared to mentioning "insufficient coverage", reporting that ">80% of young people in other countries got vaccinated" motivated vaccine acceptance (OR 1.94 [1.61-2.35]). The notion of sexual transmission did not influence acceptance. CONCLUSION: HPV vaccine communication to adolescents can be tailored to optimise the impact of promotion efforts.

Are People Optimistically Biased about the Risk of COVID-19 Infection? Lessons from the First Wave of the Pandemic in Europe.

Unrealistic optimism, the underestimation of one's risk of experiencing harm, has been investigated extensively to understand better and predict behavioural responses to health threats. Prior to the COVID-19 pandemic, a relative dearth of research existed in this domain regarding epidemics, which is surprising considering that this optimistic bias has been associated with a lack of engagement in protective behaviours critical in fighting twenty-first-century, emergent, infectious diseases. The current study addresses this gap in the literature by investigating whether people demonstrated optimism bias during the first wave of the COVID-19 pandemic in Europe, how this changed over time, and whether unrealistic optimism was negatively associated with protective measures. Taking advantage of a pre-existing international participative influenza surveillance network (n = 12,378), absolute and comparative unrealistic optimism were measured at three epidemic stages (pre-, early, peak), and across four countries-France, Italy, Switzerland and the United Kingdom. Despite differences in culture and health response, similar patterns were observed across all four countries. The prevalence of unrealistic optimism appears to be influenced by the particular epidemic context. Paradoxically, whereas absolute unrealistic optimism decreased over time, comparative unrealistic optimism increased, suggesting that whilst people became increasingly accurate in assessing their personal risk, they nonetheless overestimated that for others. Comparative unrealistic optimism was negatively associated with the adoption of protective behaviours, which is worrying, given that these preventive measures are critical in tackling the spread and health burden of COVID-19. It is hoped these findings will inspire further research into sociocognitive mechanisms involved in risk appraisal.

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.