In short
There are currently 2 clinical trials investigating vaccination strategies for people without a functioning spleen. These trials are evaluating how different vaccines against bacterial infections work in patients with asplenia, comparing immune responses and timing of vaccination to help protect against serious infections.
Clinical trial locations
- France
- Netherlands
Study of Pneumococcal Vaccine Response in Patients Without a Spleen: Comparing Vaccination Before and After Spleen Removal Using PCV20 and PCV21
This trial is taking place in the Netherlands and focuses on understanding how the immune system responds to pneumococcal vaccines in people without a spleen. The spleen plays an important role in fighting infections, particularly from bacteria called pneumococcus that can cause serious illnesses like pneumonia and meningitis.
Main focus: The study compares two vaccines, Prevenar 20 and CAPVAXIVE, to determine the best timing for vaccination - either before or after surgical removal of the spleen. Participants will receive both vaccines over a period of approximately two years, with blood tests measuring how well the immune system creates antibodies to fight pneumococcal bacteria.
Investigational drugs: The trial uses PCV20, a pneumococcal conjugate vaccine protecting against 20 different types of pneumococcal bacteria, and PCV21, which protects against 21 strains. PCV20 is given first as the primary vaccination, followed by PCV21 at least 12 months later as a booster to strengthen the body's immune response.
Who can participate: The trial is looking for adults aged 18 to 65 years who either have already had their spleen removed or are scheduled for spleen removal surgery. Eligible participants include those undergoing spleen removal due to pancreatic cancer, precancerous pancreatic lesions, or blood disorders such as thalassemia or sickle cell disease. Participants must not have received pneumococcal conjugate vaccines before, except for PCV20.
Who cannot participate: People under 18 or over 65 years of age cannot join the study. Those with previous allergic reactions to pneumococcal vaccines, current infections or fever above 38°C, or weakened immune systems are excluded. Pregnant or breastfeeding women, those who have received other vaccinations in the past 30 days, or people taking medications that affect the immune system are also not eligible. Anyone unable to complete the full study schedule or with poorly controlled chronic illness cannot participate.
Study on the Safety and Immune Response of Meningococcal B Vaccines in Adults with Asplenia: Bexsero, Trumenba, and a Drug Combination
This clinical trial is being conducted in France and examines the effectiveness and safety of different vaccine strategies to prevent infections caused by meningococcal group B bacteria. People without a functioning spleen are at higher risk for these serious, potentially life-threatening infections.
Main focus: The study evaluates three different vaccination strategies using Bexsero and Trumenba vaccines. The primary goal is to assess how well these vaccines generate an immune response in adults with asplenia. Researchers will monitor participants for several months, with the main evaluation occurring one month after completing the vaccine series, and long-term follow-up continuing for 4 years.
Investigational drugs: The trial tests SPLEMENGO, a meningococcal B vaccine designed to protect against infections. Bexsero contains several components made using recombinant DNA technology, while Trumenba includes proteins from two subfamilies of the meningococcal group B bacteria. Both vaccines are given as injections into the muscle.
Who can participate: The trial is open to men and women between 18 and 75 years old who have been without a functioning spleen for at least two weeks. This must be confirmed by the presence of Howell Jolly bodies in a blood test, which are small remnants visible under a microscope that indicate the spleen is not working. Spleen removal must be documented by a doctor's report or ultrasound. Women who can have children must use effective birth control during the first 9 months of the study. Participants must have social security coverage or equivalent.
Who cannot participate: The trial has limited information on specific exclusion criteria but mentions that individuals outside the specified age range and those belonging to vulnerable populations requiring special protection or care may not be eligible.
Summary
Both trials address an important healthcare need for people with asplenia, who face increased risk of serious bacterial infections. One trial focuses on pneumococcal vaccines in the Netherlands, while the other examines meningococcal B vaccines in France. The Dutch study is particularly innovative in comparing vaccination timing relative to spleen removal surgery, which could help doctors determine the optimal moment to vaccinate patients. The French trial offers a long-term perspective with 4 years of follow-up monitoring. Together, these studies aim to improve vaccination strategies and protection for adults living without a functioning spleen.
