A Study of 9-valent Extraintestinal Pathogenic Escherichia Coli Vaccine (ExPEC9V) and High-dose Quadrivalent Influenza Vaccine, With and Without Co-administration, in Adults Aged 65 Years or Older

The purpose of this study is to show that high-dose quadrivalent seasonal influenza vaccine (HD QIV) given together with 9-valent extraintestinal pathogenic Escherichia coli vaccine (ExPEC9V) does not induce lower antibody response against each of the 4 influenza vaccine strains, as compared to HD QIV given alone and further show that ExPEC9V given together with HD QIV does not induce lower antibody response against each of the vaccine O-serotype antigens, as compared to ExPEC9V given alone.