Influenza during pregnancy: Incidence, vaccination coverage and attitudes toward vaccination in the French web-based cohort G-GrippeNet

{Introduction: Pregnancy is a risk factor for severe influenza. However, data on influenza incidence during pregnancy are scarce. Likewise, no data are available on influenza vaccine coverage in France since national recommendation in 2012. We aimed to assess these points using a novel nationwide web-based surveillance system, G-GrippeNet. Methods: During the 2014/2015 influenza season, pregnant women living in metropolitan France were enrolled through a web platform (https://www.grippenet.fr/). Throughout the season, participants were asked to report, on a weekly basis, if they had experienced symptoms of influenza-like-illness (ILI). ILI episodes reported were used to calculate incidence density rates based on period of participation from each participant. Vaccination coverage was estimated after weighing on age and education level from national data on pregnant women. Factors associated with higher vaccination coverage were obtained through a logistic regression with Odds Ratio (OR) corrected with the Zhang and Yu method. Results: A total of 153 women were enrolled. ILI incidence density rate was 1.8 per 100 person week (95%CI, 1.5-2.1). This rate was higher in women older than 40 years (RR=3.0, 95%CI [1.1-8.3]