UTI Vaccine Shows Promise

Interest in a vaccine for urinary tract infections (UTIs) extends back to the 1950s. Since then, scientists have been looking for a viable candidate to prevent the bacteria Escherichia coli (E. coli) from colonizing the bladder and establishing an infection.

In July 2017, the U.S. Food and Drug Administration (FDA) granted Sequoia Sciences' FimH UTI vaccine fast-track designation. If approved, the vaccine would become the first vaccine approved for the treatment of UTIs in the United States.

About UTIs

UTIs are one of the most frequent clinical bacterial infections in women, accounting for nearly 25% of all infections.

In tandem with the widespread use of antibiotics, there has been an increase in the number of antibiotic-resistant bacteria that cause severe UTIs. When this occurs, the infection can ascend from the bladder (where it is referred to as cystitis) into the kidneys (causing pyelonephritis).

In some cases, the infection can further spread into the blood and cause sepsis. Kidney damage, hospitalization, and even death are consequences of a severe, untreated UTI infection.

In light of this threat, there has been growing interest in developing a vaccine that obviates the need for antibiotics. This is especially important for women who experience recurrent or chronic UTIs and are at greater risk of multi-drug resistance due to frequent use of antibiotic drugs.

About the FimH Vaccine

The FimH vaccine is a specific-antigen vaccine. This is a vaccine that contains a protein—in this case, the FimH bacterial adhesion protein—which the body recognizes as harmful. In response, the immune system will produce antibodies designed to control that specific organism.

The FimH protein works by providing E.coli the means to attach to cells on the surface of the bladder. By doing so, the bacteria can colonize and spread. Without the FimH protein, E. coli would be ill-equipped to do this.

Due to advances in DNA technology, specific-antigen vaccines have become popular vaccine models of vaccine development compared to more traditional whole-killed vaccines or inactivated vaccines.

Early-Phase Trial Results

The FimH vaccine is not new. It was originally licensed by MedImmune (a wholly-owned subsidiary of AstraZeneca) in the late 1990s and entered phase 1 and phase 2 clinical trials before being dropped from development.

Sequoia Sciences then licensed the vaccine, changed the adjuvant (a substance that bolsters the immune response), and embarked on trials of its own. The early results have been positive.

Of the 67 women enrolled in this first study, 30 had a two-year history of recurrent UTIs while the remaining 37 had no history of UTIs. Ages ranged from 18 to 64.

The women were divided into groups and given various injections, some of which involved 50 micrograms (µg) of the FimH vaccine adjuvanted with different doses of a synthetic lipid called PHAD. Others were given an unadjuvanted vaccine or a placebo.

A total of four vaccinations were injected into the deltoid muscle of the upper arm over the course of 180 days (days 1, 31, 90, and 180).

At the end of the trial period, women given the adjuvanted vaccine had a 10-fold increase in FimH antibody, suggesting a strong immune defense.

Overall, the vaccine was said to be well-tolerated and to have generated a robust enough immune response to warrant the FDA's fast track designation.

Although the phase 1 research was completed in 2017, the results were only published in their entirety in the January 2021 issue of Human Vaccines and Immunotherapies.

ExPEC4V: Another Vaccine Candidate

Janssen Pharmaceuticals and GlycoVaxyn have also been working on another UTI vaccine called ExPEC4V. Unlike the Sequoia Sciences vaccine, the ExPEC4V vaccine is a conjugate vaccine. This is a vaccine that fuses the antigen to a carrier molecule to increase its stability and efficacy.

The phase 1 trial involved 188 women, 93 of whom received the vaccine and 95 of whom received a placebo. Participants were between ages 18 and 70. All had a history of recurrent UTIs.

According to the researchers, the ExPEC4V vaccine was well-tolerated and induced a significant immune response, resulting in fewer UTIs caused by E. coli.

Phase 2 results were also relatively positive. For this phase of the study, two injections were given: one on the first day of the trial and another 180 days later.

According to research published in Open Forum Infectious Diseases, women who received the ExPEC4V vaccine had a two-fold increase in the antibody response compared to those who received the placebo, who had none.

Side effects were generally mild to moderate (mainly fatigue and injection site pain), although they occurred at twice the rate in the vaccine group as the placebo group.

Research is ongoing.

A Word From Verywell

Women who experience recurrent UTIs will likely be ideal candidates for a UTI vaccine should one be approved. The repeated use of antibiotics in women with chronic infections only increases the risk of multi-drug resistance, both individually and within the larger population.

Until such time as a vaccine is available, be sure to see your primary care physician or a urologist if you experience recurrent UTIs. And, more importantly, don't request an antibiotic if one isn't offered. Limiting use helps prevent the development of antibiotic-resistant bacterial strains.

Leading healthcare organizations, including the Centers for Disease Control and Prevention (CDC) and the World Health Organization, have declared antibiotic resistance as one of the most serious health threats facing the world today.