The parts of a system must be related; they must be "designed to work as a coherent entity" — otherwise they would be two or more distinct systems. Theoretical framework
Most systems are open systems, exchanging matter and energy with their respective surroundings; like a car, a coffeemaker, or Earth. A closed system exchanges energy, but not matter, with its environment; like a computer or the project Biosphere 2. An isolated system exchanges neither matter nor energy with its environment. A theoretical example of such system is the Universe.Process and transformation process
An open system can also be viewed as a bounded transformation process, that is, a black box that is a process or collection of processes that transform inputs into outputs. Inputs are consumed; outputs are produced. The concept of input and output here is very broad. For example, an output of a passenger ship is the movement of people from departure to destination.System model
A system comprises multiple views. Man-made systems may have such views as concept, analysis, design, implementation, deployment, structure, behavior, input data, and output data views. A system model is required to describe and represent all these views.Systems architecture
A systems architecture, using one single integrated model for the description of multiple views, is a kind of system model. Subsystem
A subsystem is a set of elements, which is a system itself, and a component of a larger system. The IBM Mainframe Job Entry Subsystem family (JES1, JES2, JES3, and their HASP/ASP predecessors) are examples.
The first inactive tetanus toxoid was discovered and produced in 1924. A more effective adsorbed version of the vaccine, created in 1938, was proven to be successful when it was used to prevent tetanus in the military during World War II. DTP (which is the combined vaccine for diphtheria, tetanus, and pertussis) was first used in 1948, and was continued until 1991, when it was replaced with an acellular form of the pertussis vaccine due to safety concerns. Half of those who received the DTP vaccine had redness, swelling, and pain around the injection site, which convinced researchers to find a replacement vaccine. Two new vaccines were launched in 1992. These combined tetanus and diphtheria with acellular pertussis (TDaP or DTaP), which could be given to adolescents and adults (as opposed to previously when the vaccine was only given to children). References
Further reading
Liang JL, Tiwari T, Moro P, Messonnier NE, Reingold A, Sawyer M, Clark TA (April 2018). "Prevention of Pertussis, Tetanus, and Diphtheria with Vaccines in the United States: Recommendations of the Advisory Committee on Immunization Practices (ACIP)" (PDF). MMWR Recomm Rep. 67 (2): 1–44. doi:10.15585/mmwr.rr6702a1. ISSN 1057-5987. PMC 5919600. PMID 29702631. Kahn KE, Black CL, Ding H, Williams WW, Lu PJ, Fiebelkorn AP, Havers F, DAngelo DV, Ball S, Fink RV, Devlin R (September 2018). "Influenza and Tdap Vaccination Coverage Among Pregnant Women - United States, April 2018" (PDF). MMWR Morb. Mortal. Wkly. Rep. 67 (38): 1055–1059. doi:10.15585/mmwr.mm6738a3. PMC 6188122. PMID 30260946. World Health Organization (2018).