Influenza vaccination and fetal and neonatal outcomes.

As pregnant women are considered a high-risk group for severe influenza illness, current recommendations advise vaccination of all pregnant women with inactivated influenza vaccine. Nevertheless, rates of maternal influenza vaccination have historically been low, possibly reflecting ongoing concerns about vaccine safety. Until recently, the majority of evidence concerning safety of influenza vaccination during pregnancy was limited to post-marketing pharmacovigilance studies; however, in the past 5 years, one randomized clinical trial and a number of observational studies reflecting seasonal trivalent inactivated influenza vaccines and monovalent H1N1 influenza vaccines have been published. This review summarizes the evidence pertaining to fetal and neonatal outcomes following influenza vaccination during pregnancy for comparative analytic studies published between 2008 and August 2013. Since the majority of these studies are observational in nature, issues related to study quality are also addressed.