Abscess
Occurrence of a fluctuant or draining fluid-filled lesion at the site of injection with or without fever.
• Bacterial: Purulent condition
• Sterile abscess: No evidence of bacterial infection Acute flaccid paralysis
Acute onset of flaccid paralysis of one or both limbs following any vaccine. Active immunity
The production of antibodies against a specific disease by the immune system. Active immunity can be acquired in two ways, either by contracting the disease or through vaccination. Active immunity can wane but is usually permanent, meaning an individual is protected from the disease for the duration of their lives. Adverse event following immunisation (AEFI)
An unwanted reaction following administration of a vaccine, which may or may not be caused by the vaccine; adverse events may be at the site of injection, or may be a general illness or a general allergic reaction. Adjuvant
A preparation (e.g. aluminium salts), which may be added to a vaccine to improve the immune response to the vaccine. Allergic reaction
An allergy is an immune system malfunction whereby a person's body is hypersensitised to react immunologically to typically innocuous substances. There are different types of hypersensitivity with different mechanisms. Of particular relevance to vaccination are the type I and type II hypersensitivity reactions: Type I hypersensitivity (immediate) is characterised by excessive activation of mast cells by immunoglobulin E resulting in a systemic inflammatory response that can result in symptoms as benign as a runny nose, to life-threatening anaphylactic shock and death. Allergy is characterised by a local or systemic inflammatory response to allergens. Local symptoms are:
• Nose: swelling of the nasal mucosa (allergic rhinitis)
• Eyes: redness and itching of the conjunctiva (allergic conjunctivitis)
• Airways: bronchoconstriction, wheezing and dyspnoea, sometimes outright attacks of asthma.
• Skin: various rashes, such as eczema, hives (urticaria) and contact dermatitis.
• Systemic allergic response is also called anaphylaxis. Depending of the rate of severity, it can cause cutaneous reactions, bronchoconstriction, edema, hypotension, coma and even death (see anaphylaxis). Apart from ambient allergens, allergic reactions can be due to medications (including vaccination). Type II hypersensitivity (delayed) Type IV hypersensitivity is often called delayed type as the reaction takes two to three days to develop. Unlike the other types, it is not antibody mediated but rather is a type of cell-mediated response. Amino Acids
Amino acids are the basic structural building units of proteins. They form short polymer chains called peptides or polypeptides, which in turn form structures called proteins. Fragments of only a few amino acids in length are required for immune recognition. Anaphylaxis
Inflammatory reactions resulting from combination of a soluble antigen with IgE bound to a mast cell that leads to degranulation of the mast cell and release of histamine and histamine like substances, causing localised or global immune reponses.
Symptoms can include the following:
• Respiratory distress,
• Hypotension,
• Fainting,
• Unconsciousness,
• Urticaria,
• Flushed appearance,
• Angioedema,
• Tears (due to angioedema and stress),
• Vomiting,
• Itching, and
• Anxiety, including a sense of impending doom
The time between ingestion of the allergen and anaphylaxis symptoms can vary depending on the amount of allergen ingested and sensitivity. Symptoms can appear immediately, or can be delayed by half an hour to several hours after ingestion. However, symptoms of anaphylaxis usually appear very quickly once they do begin. Anaphylactic shock
The most severe type of anaphylaxis, will usually lead to death in minutes if left untreated. Anaphylactoid
A reaction that is similar to anaphylactic shock but is unrelated to antigen-antibody reactions. The mechanism is independent of IgE. The clinical presentation is indistinguishable from anaphylaxis and treatment is the same.
Antibody
An antibody is a protein used by the immune system to identify and neutralize foreign objects like bacteria and viruses. Each antibody recognises a specific antigen unique to its target. Production of antibodies is referred to as the humoral immune system. There are several classes of antibody. Also referred to as Immunoglobulin (Ig). Antigen
An antigen is a substance that stimulates an immune response, especially the production of antibodies. Antigens are usually proteins or polysaccharides (sugars), but can be any type of molecule, including small molecules (haptens) coupled to a carrier-protein. Arthralgia
Joint pain without redness or swelling. Arthritis
Joint pain together with redness and/or swelling. Attenuation
The process of modifying a virus or bacteria so as to reduce its virulence while retaining its ability to induce a strong immune response (immunogenicity). Bacteria
A major group of living organisms that are smaller than a blood cell but bigger than a virus; examples of bacterial infections are diphtheria, tetanus, pertussis, and tuberculosis. Most are microscopic and unicellular, with a relatively simple cell structure lacking a cell nucleus and organelles such as mitochondria and chloroplasts BCG
Bacillus of Calmette Guérin, a vaccine that protects against tuberculosis. Brachial Neuritis
Pain in arm causing weakness of limb on side of vaccination. A rare adverse reaction described in adults following diphtheria-tetanus vaccines. Carrier
A person who has an infection, which may still be active and may spread to others; the carrier state may last for years. Examples of infections that can result in the carrier state are hepatitis B and typhoid. Cellular mediated immunity
Immune response that involves effector T lymphocytes and not the production of humoral antibody. Cilia
Cilia are projections from the cell found in all animals, usually present on a cell's surface in large numbers that beat in coordinated waves. In humans, for example, motile cilia are found in the lining of the trachea, where they sweep mucus and dirt out of the lungs. Conjugate
(Paired together) Some vaccines (eg. pneumococcal conjugate vaccine) are made from the chemical linking (conjugation) of the bacterial polysaccharide cell coat with a protein carrier such as tetanus toxoid, in order to improve the immune response to the vaccine. Contraindication
Any condition, especially any condition of disease, which renders some particular line of treatment improper or undesirable. Corticosteroid
Used clinically for hormonal replacement therapy, suppression of ACTH secretion by the anterior pituitary, antineoplastic, antiallergic and anti-inflammatory agents and to suppress the immune response. Cytokines
Cytokines are small protein molecules that regulate communication among immune system cells and between immune cells and those of other tissue types. Cytokines are actively secreted by immune cells as well as other cell types in response to external stimuli. Deoxyribonucleic Acid (DNA)
Deoxyribonucleic acid (DNA) is a nucleic acid, usually in the form of a double helix, that contains the genetic instructions specifying the biological development of all cellular forms of life including most viruses. DNA is a long chain (polymer) of nucleotides and encodes the sequence of the amino acids in proteins using the genetic code, a triplet code of nucleotides. Efficacy
The ability of a vaccine to protect against disease under trial conditions i.e. the number of immunised people getting disease divided by the number immunised. Effectiveness
The ability of a vaccine to prevent disease in a population. A vaccine may be only 85% efficacious however with high coverage may reach 100% effectiveness by eradicating disease from the population.
Encephalitis
Inflammation of the brain. Encephalopathy
A general term to describe a variety of illnesses that affect the brain, including encephalitis. A very rare adverse reaction temporally linked with vaccination: acute onset of major neurological illness characterized by any 2 or more of the following conditions:
• Seizures
• Severe alteration in level of consciousness or mental status lasting for one day or more; and/or
• Focal neurological signs which persist for one day or more. Enchephalitis
Characterised by the above symptoms (encephalopathy) and signs of cerebral inflammation and, in many cases, CSF pleocytosis and/or virus isolation. Endemic
Endemic infections are present all the time in a community. An example is pnuemococcal disease. Epidemic
Epidemic infections are those that spread rapidly in a community; measles and influenza viruses are common causes of epidemics. Small epidemics are often called outbreaks. An epidemic occurs suddenly in numbers clearly in excess of normal expectancy, said especially of infectious diseases but applied also to any disease, injury or other health related event occurring in such outbreaks. Epitope
An epitope is the part of a foreign organism or its proteins that is recognised by the immune system and targeted by antibodies, cytotoxic T cells or both. Most epitopes can be thought of as three-dimensional surface features of an antigen molecule although some are linear epitopes which are determined by the amino acid sequence (the primary structure) rather than by the tertiary structure (the 3-dimensional shape) of a protein. Excipient
Any more or less inert substance added to a prescription in order to confer a suitable consistency, as a vehicle, or an active ingredient. Excipients can also be used to aid the process by which a product is manufactured. In general, the active substances i.e. antigen may not be easily administered and absorbed by the human body; they need to be put in some appropriate form. The active substance is then dissolved or mixed with an excipient. Extensive limb swelling
Can occur as an AEFI: swelling and/or redness over a substantial area, involving at least half the circumference of the limb, and the joint both above and below the injection site, commencing within 48 hours of vaccination and resolving completely without sequelae. Febrile
Related to a fever, as in febrile illness and febrile convulsions. Guillain-Barré Syndrome (GBS)
Acute onset of rapidly progressive, ascending, symmetrical flaccid paralysis, without fever at onset of paralysis and with or without sensory loss. Cases are diagnosed by CSF investigation showing dissociation between cellular count and protein count. HBsAg
Hepatitis B surface antigen expressed abundantly on the hepatitis B virus coat; a marker in the blood that indicates that the person is a carrier of active hepatitis B virus infection. Hepatitis
An inflammation of the liver; can be caused by viral infections. Humoral immunity
A form of immunity whereby B lymphocytes and plasma cells produce antibodies to antigens and stimulate T lymphocytes to attack them (cellular immunity). Hypotonic-hyporesponsive episode (HHE)
A rare reaction, which may follow some hours after vaccination; the child becomes pale, limp and unresponsive; the condition may last from a few minutes to hours but causes no long-term serious problems. Immunisation
The process of inducing immunity to an infectious agent by administering a vaccine. Immunity
The ability of the body to fight off certain infections; immunity can result from natural (’wild’) infections or from vaccination. Immunogenicity
The ability of a vaccine to induce protective levels of humeral or cellular immunity. Immunoglobulin
A specific protein substance that is produced by plasma cells to aid in fighting infection. Injection of immunoglobulins provides temporary immunity against certain infections. Examples include IgG, IgM, IgA, IgD and IgE. Incubation period
The development of an infectious disease, from the entrance of the pathogen to the appearance of clinical symptoms. Jaundice
Yellowing of the skin (and whites of eyes) by bilirubin, a bile pigment, frequently because of a liver problem. Lysozyme
Lysozyme is an enzyme, commonly referred to as the "body's own antibiotic" since it kills bacteria. It is abundantly present in a number of secretions, such as tears, cytoplasmic granules of the polymorphonuclear neutrophils (PMN) and released through the mucosal secretions (such as tears and saliva). Meningitits
Acute onset of major illness with fever and often neck stiffness/positive meningeal signs. Symptoms may be subtle or similar to those of encephalitis. CSF pleocytosis is usual. Mutation
Mutations are changes to the genetic material (usually DNA or RNA). Mutations can be caused by copying errors in the genetic material during cell division and by exposure to radiation, chemicals, or viruses, or can occur deliberately under cellular control. Nodule
Injection site nodules are fibrous remnants of the body’s interaction with the vaccine components in the muscle. Nucleic Acid
A nucleic acid is a complex, molecule composed of nucleotide chains that convey genetic information. The most common nucleic acids are deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). Nucleic acids are found in all living cells and viruses. Oncogene
An oncogene is a modified gene that increases the malignancy of a tumor cell. Orchitis
Swelling with pain and/or tenderness of testes. Osteitis
Inflammation of the bone or boney tissue. In rare cases this can be due to BCG vaccination. Osteomyelitis
Bacterial infection of bone. Parotitis
Swelling and/or tenderness of parotid glands or glands. Passive immunity
Immunity acquired passively either from the placenta or breastmilk or from the administration of immunoglobulin. Passive immunity is only transient. Peptides
Family of molecules formed from the linking, in a defined order, of various amino acids. Phagocytes
A phagocyte is a cell that ingests (and destroys) foreign matter, such as microorganisms or debris via cellular digestion, a process known as phagocytosis, in which these cells ingest and kill offending cells by cellular digestion. These phagocytes are extremely useful as an initial immune system response to tissue damage. Polysaccharide
A group of complex carbohydrates (sugars). These can be found on the outside coating of some bacteria. Polysaccharides are not immunogenic in the very young. Protein
Complex, organic compound consisting of amino acids joined by peptide bonds. Proteins are essential to the structure and function of all living cells and viruses, many are enzymes or subunits of enzymes, catalyzing chemical reactions. Other proteins play structural or mechanical roles. Proteins are one of the classes of bio-macromolecules, alongside polysaccharides, lipids, and nucleic acids that make up the primary constituents of living things. The coding sequences of genes determine the amino-acid sequences of almost all naturally occurring proteins. It is very common for proteins to work together to achieve a particular function, and often physically associate with one another to form a complex. Proteins serve important roles in both the immune system and also as antigens. Recombinant
Recombinant DNA is an artificial DNA sequence resulting from the combining of two other DNA sequences. Recombinant proteins are proteins that are produced by different genetically modified organisms following insertion of the relevant DNA into their genome. As this recombines the DNA of two different organisms, the word recombinant is used to refer to this process. An example of a recombinant vaccine is Hepatitis B vaccine where the gene encoding the hepatitis b surface antigen has been inserted in to yeast cells, which produce the protein. Ribonucleic Acid (RNA)
Ribonucleic acid (RNA) is a nucleic acid polymer. It is transcribed from DNA by enzymes. RNA serves as the template for translation of genes into proteins, transferring amino acids to the ribosome to form proteins, and also translating the transcript into proteins. Some viruses do not have DNA but have only RNA to encode their genetic material. Seizure
A sudden attack or convulsion due to involuntary electrical activity in the brain. It is due to an uncontrolled burst of electrical activity in the brain that can result in a wide variety of clinical manifestations such as: muscle twitches, staring, tongue biting, urination, loss of consciousness and total body shaking.
Examples include: focal seizure, absence seizure, partial seizure, psychomotor seizure, petit-mal seizure and grand-mal seizures. Specific immunity
The combination of humoral immunity and cell-mediated immunity specific to a particular disease. Specific immunity is acquired actively either by infection, vaccination or passively by maternal antibodies or administration of immunoglobulin. Only actively acquired immunity is long-lived. Thrombocytopenia
Platelet count <50 x 109/L Toxin
Poisonous substance produced by living cells or organisms. Toxins are nearly always proteins capable of causing disease on contact or absorption with body tissues by interacting with biological macromolecules such as enzymes or cellular receptors. Toxins vary greatly in their severity, ranging from usually minor and acute (as in a bee sting) to almost immediately deadly (as in botulinum toxin). Toxin producing bacteria include Diphtheria and Tetanus. Toxoid
A toxoid is a bacterial toxin whose toxicity has been weakened or suppressed while other properties such as immunogenicity, are maintained. Toxoids are used in vaccines as they induce an immune response to the original toxin or increase the response to another antigen. For example, the tetanus toxoid is derived from the tetanospasmin produced by Clostridium tetani and causing tetanus. Wild type
Wild type is one of the major genotypes of a species that occur in nature by evolution, in contrast to induced mutations or artificial cross-breeding. The naturally occurring variety. Vector
A mechanism that transmits genes or organisms. Virus
A virus is a submicroscopic parasite that infects cells in biological organisms. Viruses reproduce only by invading and controlling other cells as they lack the cellular machinery for self-reproduction. Examples include measles, hepatitis and polio viruses. Virulence
Virulence is a term used to refer to either the relative pathogenicity or the relative ability to do damage to the host of an infectious agent.
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