There are three main types of metadata: â¢ Descriptive metadata describes a resource for purposes such as discovery and identification.It can include elements such as title, abstract, author, and keywords. â¢ Structural metadata indicates how compound objects are put together, for example, how pages are ordered to form chapters.â¢ Administrative metadata provides information to help manage a resource, such as when and how it was created, file type and other technical information, and who can access it. Structural metadata indicates how compound objects are put together, for example, how pages are ordered to form chapters. â¢ Administrative metadata provides information to help manage a resource, such as when and how it was created, file type and other technical information, and who can access it.
Sabinâs live-virus, oral polio vaccine (administered in drops or on a sugar cube) soon replaced Salkâs killed-virus, injectable vaccine in many parts of the world.
Two forms of vaccine are in use, the whole-cell vaccine (wP), and the acellular vaccine (aP). Whole-cell pertussis vaccines were developed first and are suspensions of the entire B. pertussis organism that has been inactivated, usually with formalin. Most wP vaccines are available in combination with diphtheria (D) and tetanus (T) vaccines, contain aluminum salts as an adjuvant and, thiomersal as a preservative.