This clinical trial aims to study immune responses to Prevenar 20, a vaccine that helps prevent pneumococcal infection. The vaccine contains 20 different types of pneumococcal bacteria and is given as an injection into the muscle. The study focuses on healthy adults between 78 and 84 years old who previously received a different pneumococcal vaccine called PPSV23 in 2020.
The study will evaluate how well the immune system responds to Prevenar 20 when given as a booster vaccination. Participants will receive a single 0.5 milliliter dose of the vaccine. Blood samples will be collected before vaccination, one month after, and eleven months after to measure the body’s immune response to the vaccine.
The research will also examine immune responses in the mucous membranes, which are the body’s natural protective barriers. These measurements will help determine how effectively the vaccine stimulates both general and localized immunity against pneumococcal bacteria, which can cause serious infections like pneumonia.
The Netherlands 
