The purpose of the study is to evaluate how well the MenQuadfi vaccine works and how safe it is when given as a booster dose to children and adolescents. These participants had previously received the vaccine as toddlers. The study will look at how the immune system responds to the booster dose and how long the protection lasts. Participants will receive the vaccine through an injection into the muscle, and the study will monitor their immune response over time.

Throughout the study, researchers will collect information on the participants’ immune responses to the vaccine and any side effects they may experience. This will help determine the effectiveness of the booster dose in maintaining protection against meningococcal infection. The study aims to provide valuable insights into the long-term benefits of the MenQuadfi vaccine in preventing serious bacterial infections in children and adolescents.

The research involves three different age groups: children aged 2 to 9 years, toddlers aged 12 to 15 months, and infants aged 2 months. Some participants will receive the new MenPenta vaccine alone, while others will receive it along with standard childhood vaccines. The study will monitor how well the immune system responds to the vaccine and track any side effects that may occur.

During the study, participants will receive multiple doses of vaccines through intramuscular injection. Blood samples will be taken to measure the body’s immune response to the vaccines. The researchers will carefully monitor all participants for immediate reactions after vaccination and continue to track their health throughout the study period. Other routine vaccines that may be given during the study include Prevenar 13 (for protection against pneumococcal disease), Hexyon (a combination vaccine that protects against six different diseases), and RotaTeq (for protection against rotavirus).

Participants in the study will receive two doses of the Bexsero vaccine. The vaccine is given as an injection into the muscle. The study will last for a total of 56 days, during which participants will have their blood tested to measure the levels of antibodies, which are proteins made by the immune system to fight infections. These tests will help researchers understand how well the vaccine works in different people.

The study will also look at how certain immune cells, called T cells, respond to the vaccine. T cells are a type of white blood cell that play a crucial role in the immune system by helping to protect the body against infections. By comparing the immune responses of transgender and cisgender participants, the study aims to provide valuable insights into how gender and sex may influence the effectiveness of the Bexsero vaccine.

The purpose of the study is to investigate how well the immune system of older adults responds to the vaccine. Participants will receive the vaccine and then have their blood tested to measure the levels of protective antibodies, which are proteins the body makes to fight infections. The study will also look at how these antibody levels change over time, both shortly after vaccination and up to five years later. This will help researchers understand how long the vaccine’s protection lasts.

Participants in the study will be older adults between the ages of 65 and 85 who have not previously received the MenACWY-TT vaccine. The study will involve receiving the vaccine and then having follow-up visits to monitor the immune response. The goal is to gather information that could help improve vaccination strategies for older adults, ensuring they are better protected against these serious infections.