Appendix D: Glossary

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Abscess

A localized collection of pus caused by infection.

Active immunity

The production of antibodies against a specific disease by the immune system, acquired by either contracting the disease or through vaccination.

Active immunizing agent

Any substance or organism that provokes an immune response (produces immunity) when introduced into the body.

Active surveillance

An active case-finding based on a regular review of hospital admission records. Canada’s pediatric active surveillance system for serious adverse events following immunization, vaccination failures, and selected infectious diseases is called Immunization Monitoring Program – Active (IMPACT).

Adaptive immunity

The body’s second line of defense, which becomes active when innate immune defenses are overcome; it has three key features: specificity, memory and diversity; its mechanisms depend on the ability of the immune system to recognize “non-self” material, to respond to its presence and to dispose of it appropriately.

Additive

The substances added to vaccines to inactivate a virus or bacteria, stabilize the vaccine, or preserve the vaccine so that it remains potent over time. Examples of vaccine additives include albumin, aluminum hydroxide, and aluminum phosphate.

Adjuvant

A substance (i.e. aluminum salt) that is added during production to increase the body's immune response to a vaccine. The adjuvant slow the release of antigens, stimulate local inflammation that attracts immune cells to the site, and enlarge the physical size of the antigen for more efficient uptake by antigen processing cells.

Adverse event following immunization (AEFI)

An undesirable experience or any unexpected medical occurrence in a patient occurring after immunization. Although a temporal relationship exists, a causal relationship is not necessarily established with the treatment or vaccine. The AEFIs are classified as being rare, uncommon, common, or very common. See Serious adverse event.

Adverse vaccine reaction

Any unexpected or dangerous reaction or unwanted effect caused by the administration of a vaccine. The adverse reaction may occur suddenly, or develop over time. See Serious adverse event.

Allergens

An antigen causing an allergic or hypersensitive response. Allergens induce the formation of IgE antibodies, a class of antibodies involved in all types of allergic reactions.

Anaphylaxis

An immediate and severe allergic response. The cardinal features of anaphylaxis as outlined in the Canadian Immunization Guide (pp. 80-84, 7^th ed.) are: itchy urticarial rash in 90% of cases; angioedema (progressive painful swelling) of face and mouth; respiratory symptoms (sneeze, cough, wheeze, dyspnea, laboured breathing); hypotension (can progress to collapse and shock).

Antibody

A protein found in the blood that is produced in response to foreign substances, (i.e. bacteria or viruses invading the body). Antibodies protect the body from disease by binding to these organisms and destroying them.

Antigen

Any substance, usually a protein that is capable of inducing an adaptive immune response.

Anxiety (or panic) attack

A sudden, unexpected period of intense anxiety often accompanied by symptoms such as heart palpitations, dizziness, trouble breathing, and intense fear of dying.

Aseptic technique

A set of practices and procedures performed under sterile conditions in order to prevent the introduction of micro-organisms, such as fungi, bacteria, and viruses.

Assent

The agreement of a person to allow diagnosis or treatment when the client does not have the capacity or legal empowerment to give informed consent, such as a child or cognitively impaired adult.

Bar coding

A method for encoding data using narrow and wide bars and spaces that represent a number or alphanumeric character. Bar coding allows for fast and accurate electronic readability. Bar codes are printed or stamped on products, labels, or other media.

Benefit

The advantage or improvement in condition provided to an individual or a population.

B-lymphocyte (B-cell)

A class of lymphocyte so called because they originate and mature in the bone marrow before being released into the bloodstream. B-cells are involved primarily in antibody-mediated immunity and produce antibodies.

Booster

A second, third, or greater immunization with a specific vaccine that may be necessary to insure that the individual is protected against the infectious disease.

Canadian Adverse Events Following Immunization Surveillance System (CAEFISS)

The main function of this system is to ensure the continued safety of vaccines on the Canadian market by monitoring adverse events following immunization.

Canadian Immunization Guide (CIG)

A guide containing information on the immunizing agents available in Canada and their use in the prevention of communicable diseases. Recommendations on routine immunizations are discussed in some detail, and an attempt is made to answer most of the day-to-day queries from providers.

Carriage

The presence of a potentially disease-causing micro-organism in an individual’s body that does not cause the disease in the carrier but may cause others to become infected.

Causality

The relationship between a cause and its effects. An effect, such as a disease, may have one or many causes, such as risk factors, predisposing factors, or precipitating factors (e.g. heart disease is caused by a combination of factors including genetic and behavioral factors).

Cell-mediated immunity (CMI)

The immune reactions that are mediated by cells, cytotoxic T lymphocytes (CTL cells) rather than by antibody or other humoral factors (e.g. complement proteins).

Cellulitis

An infection of the skin and connective tissue characterized by redness, swelling, warmth, and tenderness. May also cause fever or chills.

Client

A person in the client index or registry. May be a contact, case, control, immunization recipient or other (e.g. guardian of a client).

Clinical features

The symptoms that are based on direct observation of the patient.

Cold chain

An unbroken series of storage and distribution activities that maintains a proper temperature range during storage and handling in order to preserve the potency of the vaccine.

Combination vaccine

A single vaccine that includes antigens for the prevention of several different diseases, or that protects against several strains of a single infectious agent that causes the same disease such as the measles, mumps, and rubella (MMR) vaccine.

Communicability

The capability to spread disease from person to person, or from species to species. Also referred to as being infectious.

Community/herd immunity

A large percentage of the population is vaccinated in order to prevent the spread of certain infectious diseases. Even individuals not vaccinated (such as newborns and those with chronic illnesses) are offered some protection because the disease has little opportunity to spread within the community. Also known as “herd immunity.”

Complications

A new disease or medical condition that develops during the treatment or course of an existing disease or medical condition.

Confidentiality

In medicine, confidentiality refers to the right of the patient to have personal identifiable, medical information revealed to a healthcare professional remain private. Limits are placed on how and when such information may be disclosed to a third party.

Conflict of interest (real or perceived)

A situation where an individual or the organization that they represent has competing professional or personal interest that may make it difficult for them to fulfill their duties in an impartial manner. A conflict of interest may be real or perceived.

Contagiousness

The degree of transmissibility - ability for a disease to be transmitted from person to person through direct or indirect contact with a bodily discharge of such a patient, or with an object touched by such a patient or by bodily discharges.

Contraindication

A symptom or condition that makes it likely a life-threatening problem would occur if a vaccine is given.

Coverage rate (immunization coverage)

The proportion of the target populations that has been vaccinated through the publicly funded programs that provides certain vaccines at little or no cost.

Credible sources

The clinical trials, academic studies, or other health-related sources of information that are based on scientific evidence. Credible studies or trials should be conducted by qualified scientists or other health professionals.

Determinants of health

The various factors that when combined together contribute to the overall health status of an individual or population. These include income, educational level, healthcare access, genetics, and lifestyle.

Disclosure

The release, transfer, or provision of access to, or divulging of individually identifiable health information outside of the entity holding that information.

Effectiveness

The ability of a vaccine to produce the desired beneficial effect(s) under real-world circumstances.

Efficacy

The maximum ability of a vaccine to produce a desired effect.

Encephalitis

The inflammation of the brain caused by a virus; encephalitis can result in permanent brain damage or death.

Encephalopathy

A general term describing brain dysfunction such as encephalitis, meningitis, seizures and head trauma.

Encounter

A point of service for any type of subject that is defined by date, time, location and the type of activity (e.g. immunization, disease screening or lab results). An encounter may or may not be associated with and investigation/control record within a subject record. An encounter may or may not be associated with other encounters through an episode.

Endemic

The continual, low-level presence of disease in a community.

Epidemic

The occurrence of disease within a specific geographical area or population that is in excess of what is normally expected.

Epidemiology

A branch of medical science that deals with the incidence, distribution, and control of disease in a population. The sum of the factors controlling the presence or absence of a disease or pathogen.

Epidemiological triangle

A model for the causation of disease that involves three elements: agent, host, and environment.

Episode

A descriptive group of one or more encounters. An investigation may have zero to many episodes. Encounters not associated to an investigation or control can also be grouped into one or more episodes. An episode is named by the user or the system and is defined by a start date and (optionally) and end date.

Evidence-based decision making

The decisions that are based on a careful analysis of accurate data and proven research findings.

Expired stock

All vaccines and diluents have an expiration date by which they should be used printed on their vials and boxes. Products that are passed their expiration dates are considered expired stock and should not be administered

Expiry date

The date by which a vaccine or a diluent should be used.

Guillain-Barré syndrome

A rare neurological disease that occurs when the body's immune system attacks the peripheral nerves in the body, causing loss of reflexes and temporary paralysis. Symptoms include weakness, numbness, tingling and increased sensitivity that spreads over the body.

Hard-to-reach (individuals, groups, populations)

The individuals, groups, or populations that have the greatest difficulty accessing services (e.g. the disadvantaged, minorities, residents in remote communities).

Harm

The nature and extent of damage that could be caused by a vaccine.

Host

A person or other living organism that can be infected by an infectious agent under natural conditions.

Humoral immunity

The term humoral refers to the extracellular fluids such as serum and lymph; in this case the immune response is mediated by antibodies produced by B-cells as effector molecules. Both B- and T-cells may be involved in this response.

Hypotonic-hyporesponsive episode (HHE)

A serious adverse reaction to immunization that results in a decrease in level of responsiveness, muscle tone and activity, and pallor. HHE is most commonly reported in response to administration of the whole-cell pertussis vaccine, but also occur with a lower frequency after diphtheria-tetanus (DT) and acellular pertussis-DT (DPT) immunization.

Immunity

The protection against a disease. There are several types of immunity: passive, active and humoral. The immunity is indicated by the presence of antibodies in the blood and can usually be determined with a laboratory test.

Immunization record (professional chart and take-home)

A record of all immunization a person has received. A record is kept by the healthcare provider who gave the immunization (professional chart), and in a local or provincial registry and by the individual or their parent or guardian (take-home record).

Immunization registry

A tool to consolidate immunization records from multiple sources, including any reports of adverse events, into one confidential record.

Immunization schedules (delay, interruption, etc.)

They outline the optimum timing of primary and secondary immunizations. A delayed immunization schedule may be used when a child receives his or her primary or secondary immunizations after the recommended ages of their regional immunization schedule. When a child’s vaccinations are interrupted by more than a month, an accelerated or catch-up immunization schedule should be used.

Immunization status

A client’s immunization status conveys whether they are eligible, due or overdue for a specified vaccine.

Eligible: the earliest acceptable time period during which an immunization is considered a valid dose for immunization coverage reporting.

Due: the time period during which an immunization is considered up to date according to the NACI schedule.

Overdue: this time period is one month after an individual is due for an immunization, unless otherwise specified.

Immunizing agent

The term used to describe the different agent combinations used for immunization. These agents can be monovalent (single antigen) or multi-valent (multiple antigens e.g. MMR) vaccines. The term “vaccine” can be used interchangeably with immunizing agent.

Immunogenicity

The inherent ability of an antigen to induce a humoral and/or cell-mediated immune response; for practical purposes the antibody-mediated response is most often used to measure the immunogenicity of vaccines.

Imported

To bring or carry in micro-organisms, such as viruses and bacteria, from an outside source.

Inactivated vaccine

A vaccine made from an infectious agent that has been inactivated or killed (without affecting the antigenicity) that allows for an active immunization.

Incidence

The number of new disease cases reported in a population over a certain period of time.

Incubation period

The period between the first exposure to a pathogen and the appearance of signs or symptoms of disease; normally bacterial incubation periods are short (hours to days) compared to virus incubation periods (weeks to months).

Induration

A hardening of soft tissue caused by inflammation. It is often a sign of infection; affected skin and other soft tissue may be red, thickened, and tender.

Informed decision making (consent) for immunization and registry

A legal term related to educating patients about the benefits, risks, and alternatives of therapeutic treatment. The patient, or a parent or guardian, must understand the potential risks and benefits of the treatment (or refusing treatment) before making a decision. The informed consent insures that the patient also understands the importance and benefit of the immunization registries.

Injection error

An error made either in the substance injected into a patient or in the location of the injection into the patient resulting in harm.

Injection site

The anatomical location of injection (e.g. left deltoid, right leg).

Injection site reaction

The inflammation or damage to the tissue surrounding the injection site.

International students

The students, from countries other than Canada, for whom the immunization status is unknown.

Live attenuated vaccine

A vaccine containing live, weakened bacteria or viruses that induce active immunity.

Local reaction

A limited reaction that occurs at the point of entrance of an infecting organism or of an injection. Also known as an injection site reaction.

Lot number

The number specific to a particular lot of a vaccine that allows it to be identified.

Mandatory immunization

The immunizations that are required by law in some provinces or territories.

Medical conditions and pregnancy

A usually defective state of health or unusual condition.

Medication error

Any preventable event that may cause or lead to inappropriate medication use or patient harm while the medication is in the control of the healthcare professional or patient. May also be referred to as a preventable adverse drug event.

Medicolegal

This term pertains to the legal aspects of practicing medicine (e.g. informed consent and malpractice).

Memory response (secondary immune response)

The capacity of the body's immune system to remember an encounter with a specific antigen and to react more swiftly to the antigen in a later encounter.

Minimum vaccine intervals

The minimum amount of time that must pass before the next dose of the same vaccine is administered in order to ensure that the immune system has time to respond effectively to the first dose.

Min-Max thermometers

A thermometer that displays the current temperature and the minimum and maximum temperatures reached since the reset. It may include an alarm to indicate when a certain temperature threshold has been exceeded.

Mode of transmission

The mechanisms by which an infectious agent is spread to humans, including direct (skin-to-skin) and indirect (airborne, vector-borne, etc) methods.

Morbidity

A diseased state or symptom - the incidence of disease; the rate of sickness (as in a specified community or group).

Mortality

The level (rate) of death in a community. Usually the cause (a specific disease, a condition or an injury) is stated.

National Immunization Strategy

A comprehensive strategy to enable collaboration among levels of government to improve the effectiveness and efficiency of immunization programs across Canada.

National Vaccine Storage and Handling Guidelines for Immunization Providers

These recommendations on vaccine storage and handling for healthcare providers were developed in collaboration with the Canadian Nursing Coalition for Immunization and published by the Public Health Agency of Canada.

Natural infection

An infection or disease caused by bacteria or viruses found in the natural environment, such as measles or chicken pox.

Needle length and gauge

The needle length refers to the length of the needle’s barrel, while the needle gauge refers to the width or barrel size of the needle.

Needle stick injury

The injury caused by a needle puncture to the skin. The needle stick injuries can transmit infectious diseases, especially blood-borne viruses. They are a hazard for people who work with hypodermic needles and other needle equipment.

New Canadians

The people that have recently arrived to Canada and for whom the immunization status is unknown.

Nodule at injection site

A lump, swelling, or mass at the injection site.

Notice of compliance (NOC)

The Notices of Compliance are issued to a manufacturer following the satisfactory review of a submission to Health Canada. NOCs indicate that a manufacturer has complied with sections C.08.002 or C.08.003 and C.08.005.1 of the Food and Drug Regulations

Occupational risk groups

The people who work in specific careers that expose them to a greater proportion of risk or harm.

Oculorespiratory syndrome

A syndrome of bilateral red eyes and upper respiratory symptoms, including coughing, wheezing, chest discomfort, sore throat, and, occasionally, facial swelling, following influenza vaccination. It is usually transient.

Package insert

The information that comes with the vaccine and is written in simple language intended for the public. The insert may contain, among other things, information on the proper use of the vaccine, a short description of the disease(s) it protects from, and storage and dosage instructions. It may also list warnings, precautions, interactions and possible side effects. Instructions and contact information on what to do if serious suspected side effects occur may also be provided.

Pandemic

This term denotes a disease affecting or attacking the population of an extensive region, as when the distribution of an epidemic disease spreads around the world (e.g. flu pandemics).

Passive immunity

The protection against disease through antibodies produced by another human being or animal. Passive immunity is effective, but protection is generally limited and diminishes over time (usually a few weeks or months). For example, maternal antibodies are passed to the infant prior to birth. These antibodies protect the baby for the first 4-6 months of life.

Passive immunizing agent

A substance or organism that provides immunity for the period of time it remains within the body. A passive immunizing agent may be acquired through the transfer of antibodies from another person or animal, from mother to fetus, or through inoculation.

Passive surveillance

A system of surveillance where the responsible agency relies on mandatory reporting by front-line healthcare providers or agencies, and the responsible agency does not carry out activities designed to stimulate reporting, such as inspections of facilities or telephone calls to healthcare providers.

Polysaccharide

The long chains of sugar molecules that resemble the surface of certain types of bacteria. Polysaccharide vaccines are available for pneumococcal disease, meningococcal disease and Haemophilus Influenzae type B. They are recommended for outbreak control, for the protection of persons travelling to locations with epidemic disease attributable to vaccine serogroups, and for persons who may be at increased risk of meningococcal disease. Polysaccharide vaccines are not recommended for routine childhood immunization.

Population health prevalence

The measure of disease presence which can vary depending on the interval of time studied. “Point prevalence” refers to the presence of the disease at a given point in time (i.e. a “snapshot”). It is the number of existing cases found in a cross-sectional survey. “Period prevalence,” a less common term, refers to the number of disease cases (new and existing) within a population over a given time period.

Post-marketing surveillance

The surveillance of a vaccine that is carried out after the vaccine has been approved for sale to the general public. Post-marketing surveillance allows for the identification of rare adverse events that may only occur at a rate of 1:10,000, or 1:1,000,000 of vaccine doses given. It also allows regulators to ensure that the vaccine retains its characteristics from one lot to the next over time.

Potency

The power of medicinal agents to produce the desired effects.

Precautions

It refers to a condition that may increase the chance of an adverse reaction following immunization or that may compromise the ability of the vaccine to produce immunity. Depending on the circumstances, the vaccine may still be administered after careful consideration as to whether the potential benefits outweigh the potential harm.

Prejudice

Injury or damage resulting from some judgment or action in disregard of one’s rights.

Preservatives

They are chemical additives used to prevent bacterial and fungal contamination in vaccines.

Prevention and Health promotion

The actions and measures that reduce exposure or other risks, keep people from getting sick, or keep disease from getting worse.

Primary immune response

The response by the immune system when it encounters an antigen for the first time. Primary immune responses are primarily composed of IgM antibodies and produce immunologic memory.

Primary prevention

The prevention that is focused on encouraging good nutrition, physical fitness, and immunization among the general population. It promotes good health, which reduces the likelihood of disease occurring.

Privacy

The right of the individual to keep their personal and health information free from unauthorized disclosure by healthcare providers.

Product monograph

A description of the name, chemical formula, and uniform method for determining the strength and purity of a drug.

Protective level or Protective efficacy

It represents the percentage of vaccinated individuals protected against disease when compared to an unvaccinated group (absolute efficacy) having the same risk of disease exposure over the same period of time, or a group that has received a comparative vaccine (relative efficacy).

Protein conjugate

A compound that is composed of a protein molecule and a non-protein prosthetic group.

Protocol

A predefined set of drugs (and the associated standard Rx data) used to treat a subject as part of a complete treatment plan. Predetermined drug protocols prevent the user from having to enter multiple drugs, and all of their associated details, when creating a prescription by pre-populating this information when selected. A drug protocol may be made up of a number of standard Rx records (previously called “regimen”).

Provider

A professional who provides health services (e.g. a public health nurse).

Public health nurse (PHN)

A healthcare provider that works with individuals, groups, and communities to address health issues. Also called “community health nurse.”

Purified protein

A protein that has been isolated from a complex mixture, such as a tissue culture.

Range

In statistics, the difference between the largest and smallest values in a distribution. In common use, the span of values from smallest to largest.

Reactogenicity (reaction)

The local and systemic adverse experiences that follow immediately after or in a short period after vaccination. See Local reactogenicity and Systemic reactogenicity.

Recall

The removal of a product from market. Recalls may be voluntary or mandatory.

Reconstitution

The process of adding a liquid to a powder. Some prescription drugs and vaccines are provided as a dry powder requiring reconstitution before use.

Reminder systems

The systems to help inform those who administer vaccines that an individual patient is due for specific vaccinations.

Reservoir

Any living or non-living substance in or on which an infectious agent can live and multiply, serving as a source of infection. The reservoir is not usually injured by the presence of infectious agent.

Risk

The probability of harm being caused.

Risk behaviours

The behaviours that increase the likelihood that an individual will experience a certain event or may be harmed.

Risk communication

An exchange of information aimed at increasing the understanding of health risks.

Risk perception

The subjective judgment that an individual makes about the characteristics and severity of a risk. An individual’s perception of risk may not accurately reflect their actual level of risk.

Route of administration

The method by which a vaccine is introduced into the body. There are five routes of administration:

• Intramuscular, where the vaccine enters through the muscle;
• Subcutaneous, where the vaccine is injected under the skin;
• Intradermal, where the vaccine is placed on the skin and absorbed;
• Intranasal, where the vaccine is introduced through the nose; and
• Oral, where the vaccine is swallowed in pill, capsule, or liquid form.

Routine practices

The activities that are done to help reduce the risk of being exposed to blood, body fluids, or non-intact (broken) skin of other people. Proper hand hygiene, use of face protection (i.e. masks or shields) and gloves, safe sharps handling, and environmental cleaning are examples of routine practices.

Safety-engineered injection devices

The injective devices that are designed to help prevent needle stick injuries and reduce exposure to bloodborne pathogens. Examples of safety-engineered injection devices include hypodermic needles and syringes, pre-filled syringes, insulin-injection needles, and jet injectors.

Sequelae

A pathological condition resulting from a prior disease, injury, or attack (i.e. a sequela of polio). Verbatim from the Latin “sequela” (meaning sequel). Plural: sequelae.

Serious Adverse Event (SAE)

An adverse event that is fatal or life-threatening that results in hospitalization or prolongation of hospitalization; can also result in significant disability or incapacity, in a congenital anomaly or birth defect. SAEs must be reported to authorities and are not necessarily due to vaccination.

Serogroups

A group of micro-organisms containing a common antigen that may include more than one serotype.

Serotypes

A group of micro-organisms containing a similar set of antigens.

Special considerations

An umbrella term used to encompass contraindications, exemptions, precautions and adverse events following immunization.

Contraindications: Specific immunizations are intentionally not administered because the health risk outweighs the benefit to the recipient.

Exemptions: Clients are exempted because of prior immunity (e.g. had the immunization before or had the disease) or refusal (e.g. medical, religious, or philosophical).

Precautions: Indication that the recipient may be at an increased risk of an adverse event following immunization. If the benefit of immunization outweighs the risk, the vaccination will be administered, likely under special recommendations.

Special populations

The classifications used to identify target groups such as children, women, and travelers.

Sporadic

A disease or event that occurs infrequently and irregularly.

Stock rotation (rotation of stock)

The placement and rearrangement of vaccine vials and boxes so that those with the earliest expiration date are the most accessible, allowing them to be used first.

Subunit vaccine

The vaccines consisting of surface antigens only. Purified subunit vaccines contain purified bacterial or viral protein factions. They are generally better tolerated than whole bacteria or virus vaccines.

Surveillance

The monitoring of vaccine safety to maintain public confidence in vaccines and immunization programs. See Passive surveillance, active surveillance, and syndromic surveillance.

Syndromic surveillance

The surveillance of health data to detect epidemics, monitor their impact on public health, characterize affected populations, and monitor the effectiveness of response to the epidemic.

Systemic reaction

The general adverse effects such as fever, irritability, fatigue, anorexia, vomiting, or periods of excessive or inconsolable crying following vaccination. These reactions may cause concern to parents and physicians, but most are completely reversible with no permanent consequences.

Targeted immunization

The immunization program aimed at a specific group(s) or population(s).

Thimerosal

A mercury-based preservative used in the manufacturing process of multi-dose vaccines to prevent infections at the vaccination site.

T-lymphocyte (T-cell)

A class of lymphocytes so called because they originate in the bone marrow but mature in the thymus before being released into the bloodstream. T-cells are important in controlling cell-mediated immune reactions and B-cell development.

Toxoid

A toxin that has been treated to destroy its toxic property, but retains its capability to stimulate the production of antitoxin antibodies.

Transmissibility

The ability of a disease to be passed from an infected individual or group to a previously uninfected individual or group. An infectious disease may be transmitted by:

• droplet contact through coughing and sneezing;
• direct physical contact;
• indirect contact, usually by coming into contact with contaminated surface or soil;
• airborne transmission;
• fecal-oral transmission, usually from contaminated food or water sources; or
• vector-born transmission, where infection is carried by an insect or other animal and transmitted to humans.

Travelers

The people travelling or who have travelled to areas where high disease endemicity is possible and for whom the immunization status is unknown.

Universal immunization

The attempt to achieve maximum immunization coverage of the population or a segment of the world’s population, usually by designating a goal in which efforts will be made to ensure that a specific percentage of the population (e.g. 80 – 90%) is immunized by a specific year.

Vaccine-preventable disease (VPD)

Any infectious disease for which vaccines exist.

Voluntary immunization

The immunizations that are not required by law in some provinces or territories.

Wild type

The original parent strain of a virus, bacteria, fruit fly, mouse, or other laboratory test organism. Often refers to how organisms are found naturally, in the wild, before mutations were induced by researchers.

Wild type infection

The infection caused by the original parent strain of a virus, bacteria, fruit fly, mouse or other laboratory test organism.

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