The purpose of this study is to collect blood (serum) or plasma from healthy people who have not been exposed to N. meningitides bacteria and do not have antibodies to the bacteria. Plasma and serum are the liquid parts of blood (that is, blood without the cells in it). The main difference between plasma and serum is that plasma has proteins that help blood clot, and serum does not. An antibody is a substance made by the immune system to fight infection. Both serum and plasma contain important components called complement proteins. These proteins together with the antibody are important for the immunity against infection-causing bacteria.
This study aims to collect blood (serum) or plasma that has suitable complement from donors for use in laboratory tests to measure antibody responses of subjects participating in studies where vaccines against N. meningitidis are administered. It’s hard to find donors who have human complement that can be used for these tests. Many adults have been exposed to N. meningitidis and already have antibodies in their blood, which prevent them from being eligible to donate plasma or blood (serum) for this study.