Glossary of terms
State and Territory information:
Definitions of common terms used throughout the Immunise Australia Program website.
These terms, which can assist the public understand information about immunisation and vaccination, are presented in alphabetical order.
A B
Adverse event following immunisation (AEFI)
An unwanted or unexpected event after a vaccine is given, which may be caused by the vaccine, or may occur by chance after immunisation. Adverse events may be at the site of the injection, or be a general illness, or a general allergic reaction.
ADT
The diphtheria and tetanus vaccine for adults. Also known as dT.
Adjuvant
A preparation which may be added to a vaccine to improve the immune response to the vaccine.
Anaphylaxis
A sudden and severe allergic reaction, which results in a serious fall in blood pressure, and may cause unconsciousness and death if not treated immediately.
Attenuation
The process of changing a virus or bacteria to reduce its disease-causing ability while retaining its ability to bring about a strong immune response in a person’s body.
Bacteria/bacterium
Micro-organisms (small living organisms that can only be seen with a microscope). They are smaller than a blood cell but bigger than a virus. Examples of infections caused by bacteria are diphtheria, tetanus, pertussis, Hib and tuberculosis (See Travel medicine).
BCG
Bacillus of Calmette Guérin, a vaccine that protects against tuberculosis (See Travel medicine).
C D
Carrier
A person who has an active infection which may spread to other people. Being the carrier of an active infection may last for years and examples include hepatitis B and typhoid (See Travel medicine).
CDT
The diphtheria and tetanus vaccine for children. Also known as DT.
Chickenpox
Chickenpox (varicella) is an infection caused by the varicella-zoster virus, which belongs to the herpes group of viruses.
Conjugation
The chemical linking of the bacterial polysaccharide (sugar) cell coat with a protein carrier to improve the immune response to a bacterial vaccine.
Contraindication
A reason why a vaccine or drug should not be given.
Corticosteroid
A drug used to reduce inflammation and other immune responses.
dT
The diphtheria-tetanus vaccine for use in adults. Also known as ADT.
DT
The diphtheria-tetanus vaccine for use in children. Also known as CDT.
DTP/DTPa
A childhood vaccine that protects against diphtheria, tetanus and pertussis (whooping cough). The newer acellular vaccine, DTPa, which is made from parts of the whooping cough bacteria instead of whole bacteria, causes fewer reactions, such as fever, pain and swelling, at the injection site than the older whole-cell vaccine, DTPw.
dTpa
The diphtheria-tetanus-acellular pertussis vaccine for use in adults and adolescents.
E F
Encephalitis
Inflammation of the brain.
Encephalopathy
A general term to describe a variety of illnesses that affect the brain, including encephalitis.
Endemic
Endemic infections are present all the time in a community.
Epidemic
Epidemic infections appear in a community or area more frequently within a given time period than expected. Measles and influenza viruses are common causes of epidemics in Australia. Small epidemics are often called outbreaks.
Febrile
Related to a fever (high temperature), as in febrile illness and febrile convulsions.
G H I
HAV
Abbreviation for hepatitis A virus, the cause of infectious hepatitis, a common infection in travellers in developing countries (See Travel medicine).
HBsAg
Hepatitis B surface antigen which is found in the blood of a person who is a carrier of active hepatitis B virus infection.
HBV
Abbreviation for hepatitis B virus, a virus that is spread in various ways including blood-to-blood contact through sharing injection equipment and by sexual intercourse (See Travel medicine).
Hepatitis
Inflammation of the liver, which can sometimes be caused by a virus.
Herpes zoster infection (shingles)
This illness is caused by the reactivation of the varicella-zoster virus, which causes varicella (chickenpox). The virus can remain in the nerve cells for a long time after varicella infection (chickenpox) has gone. Symptoms of shingles include a painful rash, usually affecting adults.
Hib
Haemophilus influenzae type b - a bacterium that causes meningitis (inflammation of a membrane surrounding the brain), epiglottitis (inflammation of a membrane in the larynx) and other serious infections in babies and children.
HIV
Human immunodeficiency virus, which can over time develop into AIDS (Acquired Immune Deficiency Syndrome). People with HIV infection have weakened immunity and need special programs of vaccination to protect them against other infections.
Human papillomavirus (HPV)
A group of more than 100 different types of viruses, including over 30 that are sexually transmitted and can infect the genital area of men and women. Some of these viruses cause genital warts or cervical cancer.
Hypotonic-hyporesponsive episode (HHE)
A rare reaction which may follow some hours after DTP (diphtheria, tetanus, pertussis) vaccination. The child becomes pale, limp and unresponsive and the condition may last from a few minutes to hours but causes no long-term serious problems.
Immunisation
The process of bringing about immunity to a particular infective agent (such as a bacterium or virus) by giving a vaccine. [The terms vaccination and immunisation are not exactly the same; vaccination is the process of giving a vaccine, while immunisation is the process of both giving a vaccine and the body developing an immune response as a result of the vaccine.]
Immunity
The ability of the body to fight off certain infections. Immunity can result from natural infection or from vaccination.
Immunogenicity
The ability of a vaccine to bring about an immune response.
Immunoglobulin
A substance from blood, sometimes called an 'antibody', which fights off infection. Injection of immunoglobulins can provide temporary immunity against some infections.
Incubation period
After a person is infected with bacteria or viruses, it often takes days or weeks for the infection to cause symptoms and an obvious illness. The time between infection and the start of symptoms is called the incubation period.
Infection
An infection occurs when bacteria or viruses invade the body. If the body cannot fight the infection, it may cause an illness.
Intradermal injection
An injection into the surface layers of the skin (dermal means skin). This is used for the administration of BCG, the tuberculosis vaccine.
Intramuscular (IM) injection
An injection into the muscle. Vaccines are usually injected into a muscle of the upper outer thigh, or a muscle in the upper arm.
IPV
Inactivated poliomyelitis vaccine. An injectable vaccine that protects against polio.
J K L
JE
Japanese encephalitis - a brain infection caused by a virus (See Travel medicine).
Jaundice
Yellow skin colour that may happen when a person has severe hepatitis.
M N O
Meningococcal infection
Caused by the bacterium Neisseria meningitidis, it can cause meningitis (inflammation of the membranes around the brain and spinal cord) and other serious infections. It is also known as meningococcus.
MMR
The measles-mumps-rubella vaccine.
OPV
Oral (taken by mouth) poliomyelitis vaccine - also known as Sabin vaccine. This vaccine is no longer available in Australia.
P Q R S
Pandemic influenza
Happens when a new strain of the influenza (flu) virus appears and spreads rapidly in the community. It causes more sickness because there is little or no immunity in the community to a new strain.
Paracetamol
A medicine that helps to reduce fever, which is given to decrease reactions to vaccination. Aspirin also reduces fever, but it should never be given to children.
Pertussis
Whooping cough, an illness caused by a bacterium, Bordetella pertussis.
Pneumococcal infection
Caused by a bacterium Streptococcus pneumoniae it can cause pneumonia (lung infection) and other serious infections. It is also known as pneumococcus.
Polysaccharide
Groups of complex carbohydrates (sugars) which make up the cell coating of bacteria.
Polyvalent vaccine
A combination vaccine which protects against more than one disease. Examples include DTP (diphtheria, tetanus, pertussis vaccine) and MMR (measles, mumps, rubella vaccine).
PRP-OMP
A type of Hib vaccine, where the Hib sugar is conjugated to a meningococcal protein (see Conjugation).
PRP-T
A type of Hib vaccine, where the Hib sugar is conjugated to a tetanus protein (see Conjugation).
Rotavirus
A virus that causes severe diarrhoea, especially in children.
Rubella
A viral illness, also known as German measles.
Shingles (herpes zoster infection)
This illness is caused by the reactivation of the varicella-zoster virus, which causes varicella (chickenpox). The virus can remain in the spinal cord for a long time after varicella infection (chickenpox) has gone. Symptoms of shingles include a painful rash, usually affecting adults.
Subcutaneous (SC) injection
An injection into the tissue between the skin and the muscle underneath.
T U V
Triple Antigen
Another name for the diphtheria-tetanus-pertussis vaccine.
Vaccination
The administration of a vaccine. [The terms vaccination and immunisation are not exactly the same; vaccination is the process of giving a vaccine, while immunisation is the process of both giving a vaccine and the body developing an immune response as a result of the vaccine.]
Vaccine
A product made from whole, or extracts of, killed viruses or bacteria, or from live weakened strains of viruses or bacteria.
Varicella
Varicella (chickenpox) is an infection caused by the varicella-zoster virus, which belongs to the herpes group of viruses.
Virulence
How well or quickly a virus or bacteria is able to cause disease in a person.
Virus
An infectious agent of small size and single composition that can multiply only in the living cells of animals, plants or bacteria. Examples of infections caused by virus include measles, rubella, mumps, polio, influenza (flu) and hepatitis B.
W X Y Z
Zoster
An abbreviation for herpes zoster infection (shingles), which is a painful rash and illness caused by the reactivation of the varicella-zoster virus (chickenpox).
For more technical information about vaccines and immunisation, please refer to the Australian Immunisation Handbook 9th Edition 2008 (NHMRC).
Page last modified: 08 April, 2008