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

A Phase 3 Randomized Double-blind Controlled Study to Evaluate the Immunogenicity, Safety, and Reactogenicity of 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.

Inclusion Criteria:

• Must be medically stable at the time of vaccination such that, according to the judgment of the investigator, hospitalization within the study period is not anticipated and the participant appears likely to be able to remain on study through the end of protocol specified follow-up. A stable medical condition is defined as disease not requiring significant change in therapy during the 6 weeks before enrollment and when hospitalization for worsening of the disease is not anticipated. Participants will be included on the basis of physical examination, medical history, and vital signs performed between informed consent form (ICF) signature and vaccination
• Participant must be: a) postmenopausal (postmenopausal state is defined as no menses for 12 months without an alternative medical cause); and b) not intending to conceive by any methods
• Must sign an ICF indicating that the participant understands the purpose, procedures and potential risks and benefits of the study, and is willing to participate in the study
• Willing and able to adhere to the lifestyle restrictions specified in this protocol
• Agrees to not donate blood from the time of vaccination until 3 months after receiving the last dose of study vaccine

Exclusion Criteria:

• History of an underlying clinically significant acute or uncontrolled chronic medical condition or significant cognitive impairment or physical examination findings for which, in the opinion of the investigator, participation would not be in the best interest of the participant (for example, compromise the well-being) or that could prevent, limit, or confound the protocol-specified assessments
• Known or suspected allergy or history of severe allergic reaction, anaphylaxis, or other serious adverse reactions to vaccines or vaccine excipients
• History of severe allergic reactions (for example anaphylaxis) to any component of the high-dose (HD) quadrivalent seasonal influenza vaccine, including egg protein, or following a previous dose of any influenza vaccine
• Has had major surgery (per the investigator's judgment) within 4 weeks before administration of the first study vaccine or will not have recovered from surgery per the investigator's judgment at time of vaccination
• History of acute polyneuropathy (for example, Guillain-Barré syndrome) or chronic inflammatory demyelinating polyneuropathy