PSV-23 response impaired in IBD patients receiving immunosuppressant therapy
MedWire News: Immune response to the 23-valent pneumococcal polysaccharide vaccine (PSV-23) is impaired in patients with inflammatory bowel disease (IBD) on combination immunosuppressive therapy but is normal among those not receiving immunosuppressant drugs, researchers have found.
Treatment of IBD often requires use of immunosuppressant medications, and patients are therefore at increased risk for various infections compared with the general population.
Vaccination against pneumococcal disease is indicated for people on immunosuppressive medications, but few studies have evaluated immune responses to this or other vaccines in patients with IBD, say Gil Melmed (University of California, Los Angeles, USA) and colleagues.
For the study, the researchers immunized with PSV-23 45 patients (aged at least 18 years) with diagnosed IBD greater than 1-month duration attending a tertiary-care IBD clinic, and 19 age-matched healthy controls.
Overall, 20 patients were on combination tumor necrosis factor (TNF)-blockers and immunomodulators (Group A) and 25 were not receiving immunosuppressive therapy (Group B).
Immune response for five serotypes (6B, 9V, 14, 19F, and 23F) defined as a two-fold or greater increase from pre-vaccination titers and at least a 1 mcg post-vaccination titer was set as the primary outcome of the study.
Pre-vaccination titers were not significantly different among the three groups, but vaccine responses at 4 weeks post-vaccination were significantly lower for patients in Group A compared with those in Group B (for four out of five antigens) and controls (for all five antigens).
Furthermore, the researchers noted an overlap in response distribution between Groups A and B for antigens 6B and 23F, while the differences between Group A and controls were most pronounced only for the highest levels of response. Titers for 9V, 14F, and 19F were lowest in Group A compared with both Group B and controls.
Melmed and team say that the large response difference for serotype 14 among the IBD groups “suggests a need to study more effective immunization strategies for these patients, including consideration for the seven-valent conjugate vaccine which may show improved responses in adults who failed to mount a response to the PSV-23.”
Compared with patients in Group B and controls, those in Group A had the lowest responses for all endpoints (geometric mean titer [GMT], proportion of patients achieving at least a two-fold increase in GMT, and number of patients achieving a GMT of at least 1 mcg/ml) and for each serotype.
After controlling for age, gender, disease duration, and baseline C-reactive protein, the odds of an overall vaccine response were 4.6-fold higher among patients in Group B compared with those in Group A.
Writing in the American Journal of Gastroenterology, the team concludes: “Given the high but unpredictable likelihood of immunosuppression in patients with IBD, patients should be evaluated for immunization status and consideration of vaccinations where appropriate before starting immunosuppressive medications.”
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By Ingrid Grasmo