We need human blood to understand the immune response to infection and to test promising new vaccines against infectious diseases in the laboratory. One test is called the Serum Bactericidal Assay (or SBA), which is measure of how effective antibodies are at killing certain bacteria and can be an important measure of how effective a new vaccine may be.

The samples would be used in the laboratory analysis of clinical trials of vaccines used in adults and children, and some samples in pre-clinical (animal) experiments testing new vaccines before they enter human-stage testing. Most people have some form of protection against most bacteria already, so not everyone is a suitable blood donor for this laboratory test. We therefore start by taking a small blood sample and test this one before asking for more blood if we found yours suitable for the work we do.

Inclusion Criteria:

• Willing and able to give informed consent for participation in the study
• Aged between 18 and 70 years
• In good health as determined by medical history and clinical judgment of the Investigators
• Able to attend the scheduled visits and to comply with all study procedures
• If found to be a suitable complement that they are willing to be approached for further donations

Exclusion Criteria:

• Body weight less than 50kgs
• Have any known or suspected impairment or alteration of immune function, resulting from, as examples:congenital or acquired immunodeficiency, receipt of immunosuppressive therapy such as anti-cancer chemotherapy or radiation therapy within the preceding 12 months or long-term systemic corticosteroid therapy, receipt of immunoglobulin or any blood product transfusion within the last 3 months
• Female participants who are pregnant
• Any chronic illness that could, in the opinion of the Investigators, interfere with immune function or with the donation of large volumes of blood (e.g. thrombocytopaenia or coagulopathy, malabsorption disorders, chronic anaemia)
• An individual who is on the delegation log for the study
• Planned blood donation within 4 months of undergoing testing to assess whether the individual is a suitable Complement donor

Healthy adult volunteers, who are willing and able to give informed consent for participation in the study.