Safety Profile of GSK's Inactivated Quadrivalent Seasonal Influenza Vaccine in Belgium, Germany and Spain: Passive Enhanced Safety Surveillance Study for the 2019/2020 Influenza Season.

Seasonal influenza infects millions annually in Europe, especially young children and older adults. Annual influenza vaccination is the most effective measure to reduce the risk of infection and its complications. As the wild influenza virus strains change every year, the composition of the influenza vaccine changes as well. Since the vaccine is produced in the same way over the years, extensive safety studies are no longer required by regulatory authorities. Instead, monitoring of any unwanted medical incidents (adverse events) after vaccination is required. For the 2019/2020 season, we monitored the adverse events reported by a representative sample of people in Belgium, Germany, and Spain within 7 days after receiving GSK's seasonal influenza vaccine.Of the 1082 people who received the first dose of the vaccine, 39% reported at least one adverse event, such as pain and swelling at the injection site, tiredness, fever, headache, or dizziness. A total of 115 children under 9 years of age received two doses 4 weeks apart. After their second dose, few of these children (8%) reported adverse events. The most frequent adverse events were fever, swelling and pain at the injection site, runny nose, or irritability. No serious adverse events were reported after either the first or second dose.No serious adverse events related to GSK's seasonal influenza vaccine within the 7 days after vaccination were reported. This study supports the favourable risk­benefit safety profile of GSK's seasonal influenza vaccine.