The pathogen Pseudomonas aeruginosa is the most common infectious agent that affects cystic fibrosis patients and leads to chronic pulmonary infection and progressive lung damage. Researchers have been hard at work developing a vaccine against Pseudomonas aeruginosa to administer to cystic fibrosis patients to prevent colonization and subsequent lung damage, since the successful development of a vaccine would offer physicians a preventative means of stopping the harmful pathogen from invading the body in the first place, reducing reliance on antibiotics.
However, a recent review of clinical trials that investigated vaccines in cystic fibrosis patients suggests that more work is necessary before vaccines can be recommended for CF patients looking to prevent Pseudomonas aeruginosa infection.
“We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Trials Register… to assess the effectiveness of vaccination against Pseudomonas aeruginosa in cystic fibrosis,” wrote Dr. HK Johansen and Dr. PC Gøtzsche, both of the Nordic Cochrane Centre in Copenhagen, Denmark. The co-authors published their review, “Vaccines for Preventing Infection with Pseudomoas Aeruginosa in Cystic Fibrosis,” in The Cochrane Database of Systematic Reviews online ahead of print.
The co-authors based their recommendation against the vaccination on the result of three clinical trials. In the trials, not all of the reported vaccines were delivered via an injection — oral, parenteral, and intranasal vaccines were used. The determination of efficacy was made using untreated or control vaccine-treated cystic fibrosis patients.
In the three trials, a total of 996 cystic fibrosis patients received a vaccine. Results from these trials were stacked against vaccination. One of the larger trials reported that future vaccination development would be suspended due to a lack of efficacy. In the other large trial there seemed to be no benefit in using the vaccine to diminish relative risk for chronic infection. The small trial’s results mirrored the larger trials.
Adding to a lack of efficacy, the trials also reported an unsafe event profile. More than twice the number of adverse events were reported in the Pseudomonas aeruginosa vaccination group during the observation period of one of the trials, and there were four times as many severe adverse events.
One sign of potential efficacy was discovered in one of the larger trials. Patients had significantly high antibody titres against the antigen injected into their bodies, showing that the vaccine was capable of eliciting an immune response. Although according to the authors, “Vaccines against Pseudomonas aeruginosa cannot be recommended,” additional research may bring the vaccines to a point of efficacy.