Hand with blue glove holding petri dish with bacteria in it

UC Davis Health launches new Invasive E. coli disease vaccine trial

The potentially life-threatening infection is commonly associated with UTIs in older adults


A new clinical trial by UC Davis Health researchers will evaluate the efficacy and safety of an experimental vaccine in preventing Invasive E. coli disease (IED). The vaccine, ExPEC9V, will be tested in adults aged 60 years and older with a history of urinary tract infections.

IED is a serious and potentially life-threatening infection that is commonly associated with urinary tract infections in older adults. The disease is caused by Escherichia coli (E. coli) bacteria, commonly found in the gastrointestinal tract. Some strains of E. coli bacteria can also enter the urinary tract, causing infection. This can spread to the bloodstream and other locations in the body and cause an infection called an invasive, or systemic, infection.

“Although Invasive E. coli disease affects all ages, adults aged 60 years or older have an increased risk of developing the disease,” said Stuart Cohen, chief of Infectious Diseases and the principal investigator of the study. “The risk of developing Invasive E. coli disease is further increased in the elderly, who had a UTI in the past. Therefore, we are focusing on trying to find ways to protect adults 60 years and older.”

Clinical trial design

The study, being coordinated by Infectious Disease team members Kenzie Usher, Jaimie Figueroa, Ivy Tou, Nicole Garza, Dean Boswell and Elizabeth Robison, is a double blind, placebo-controlled clinical trial — meaning neither the participants nor the researchers know who is receiving the vaccine treatment or placebo.

Nearly 20,000 adults aged 60 years and older with a history of urinary tract infection in the past two years will participate in the worldwide study. Half of the qualified participants will receive one injection of the ExPEC9V vaccine; the other half will get  an injection of the placebo in the muscle of their upper arm.

Participants will then be monitored by researchers over a three-year period with two clinic visits and an additional six virtual visits.

Researchers will be evaluating and measuring:

  • If the study vaccine is safe
  • If the vaccine causes any side effects
  • How well the vaccine is tolerated by participants
  • How long the effects of the study vaccine last
  • How the vaccine acts in the body
  • How the body reacts to the study vaccine (the immune response)

What is the ExPEC9V vaccine?

ExPEC9V is an experimental vaccine that belongs to the group of vaccines named conjugate vaccines. Conjugate vaccines use a specific piece of the bacteria, like sugars and proteins, to generate an immune response against the bacteria.

ExPEC9V vaccine uses sugars that are part of the casing around the E. coli bacteria. These sugars are bound by means of a biotechnology process to a protein coming from another bacteria — Pseudomonas aeruginosa.

“The ExPEC9V vaccine contains clean and harmless sugars and proteins, but not the bacteria themselves. It cannot cause E. coli or P. aeruginosa infections,” Cohen explained.

The ExPEC9V vaccine works by targeting nine different strains of E. coli bacteria that are commonly associated with Invasive E. coli disease. The vaccine stimulates the body's immune system to produce antibodies that can recognize and neutralize these strains of bacteria, preventing them from causing infection.

“A vaccine to prevent Invasive E. coli disease could be an important tool to protect older adults with a history of urinary tract infection, potentially saving lives and improving quality of life for many individuals,” Cohen added.

Participation in the study

For the study, researchers are working to identify and recruit participants who meet the following criteria:

  • Men and women who are at least 60 years of age
  • Must have a history of UTI in the past two years
  • Must be medically stable
  • If female, must either be postmenopausal, permanently sterile, or not intending to conceive by any methods
  • Willing to provide verifiable identification and has means to be contacted and to contact the investigator during this study
  • No current intentions of moving or travelling for periods of longer than 30 consecutive days during the course of the study

For more information, contact the study team at HS-EMBRACE@ucdavis.edu or visit the trial’s website.