This glossary provides the common terms used in Pharmacovigilance. The terms and definitions below are based on COIMS Cumulative Glossary, with a focus on Pharmacovigilance (Version 2.1).

Adverse drug reaction (ADR), synonyms: Adverse reaction, Suspected adverse (drug) reaction, Adverse effect, Undesirable effect

A response to a medicinal product which is noxious and unintended. Response in this context means that a causal relationship between a medicinal product and an adverse event is at least a reasonable possibility. Adverse reactions may arise from use of the product within or outside the terms of the marketing authorisation or from occupational exposure. Conditions of use outside the marketing authorisation include off-label use, overdose, misuse, abuse and medication errors.

Source: Definition EU Guideline on good pharmacovigilance practices (GVP) Annex I – Definitions (08 January 2014)

Adverse event (AE)

Any untoward medical occurrence in a patient or clinical trial subject administered a medicinal product and which does not necessarily have a causal relationship with this treatment.

Source: Definition EU Guideline on good pharmacovigilance practices (GVP) Annex I – Definitions (08 January 2014)

Adverse event following immunization

Any untoward medical occurrence which follows immunization, and which does not necessarily have a causal relationship with the usage of the vaccine. The adverse event may be any unfavourable or unintended sign, abnormal laboratory finding, symptom or disease.

Proposed by the CIOMS/WHO Working Group on Vaccine Pharmacovigilance.

Causality assessment

The evaluation of the likelihood that a medicine was the causative agent of an observed adverse event in a specific individual. Causality assessment is usually made according to established algorithms.

Modified from: Glossary of terms used in Pharmacovigilance. WHO Collaborating Centre for International Drug Monitoring, Uppsala.

Clinical trail

A research study, in a defined and controlled setting, where participants are assigned prospectively to one or more (or no) interventions to evaluate the effects of the intervention on biomedical or health-related outcomes. The research is performed according to a written protocol. The intervention may be a medicine, vaccine, device, diagnostic or surgical procedure, or change in behavior (e.g. diet).

Modified from: ClinicalTrials.gov. Glossary of Common Site terms. Definition of ‘Interventional study (clinical trial)’

Clinical study

A research study involving human volunteers (also called participants) that is intended to add to medical knowledge. There are two broad types of clinical studies: interventional studies (also called clinical trials) and observational studies.

Source: ClinicalTrials.gov. Glossary of Common Site terms. Definition of ‘Clinical study’

Cohort event monitoring (CEM)

A surveillance method that requests prescribers to report all observed adverse events, regardless of whether or not they are suspected adverse drug reactions, for identified patients receiving a specific drug. Also called prescription event monitoring.

Source: Glossary of terms used in Pharmacovigilance. WHO Collaborating Centre for International Drug Monitoring, Uppsala.

Coincidental event

An adverse event following immunization (AEFI) that is caused by something other than the vaccine product, immunization error or immunization anxiety.

Source: CIOMS, Definition and Application of Terms for Vaccine Pharmacovigilance, 2012

Dechallenge / Rechallenge

Dechallenge is the withdrawal of a drug from a patient to observe whether an adverse event (AE) continues.

• If the AE continues, this is designated a negative dechallenge, and a causal relationship is less likely.
• If the AE decreases in severity or disappears, this is designated a positive dechallenge, and a causal relationship is more likely.

Rechallenge is the reintroduction of the drug to the patient.

• If the AE reappears, this is designated a positive rechallenge and strongly suggests a causal relationship.
• If the AE does not reappear, this is designated a negative rechallenge, and suggests there is no causal relationship.

Partial dechallenge is a reduction of the drug dose to observe whether an adverse event continues or not. Partial rechallenge is a gradual reintroduction of the drug to observe whether the AE reappears or not. Note: In its report, the CIOMS Working Group stated that rechallenge should only be carried out intentionally “when there is likely to be clinical benefit to the patient. Thus, only if in the judgment of the treating physician the anticipated result is directly relevant to the patient’s treatment and well being should that individual be rechallenged.”

Proposed by the CIOMS Glossary Advisory Board.

Expected and Unexpected adverse drug reaction

An expected adverse drug reaction (ADR) is one for which its nature or severity is consistent with that included in the appropriate reference safety information (e.g., Investigator’s Brochure for an unapproved investigational drug or package insert/summary of product characteristics for an approved product).

Modified from: CIOMS Working Group V report, p. 109.

An unexpected ADR is defined as: An adverse reaction, the nature or severity of which is not consistent with the applicable product information (e.g., Investigator’s Brochure for an unapproved investigational drug or package insert/summary of product characteristics for an approved product).

Source: ICH Guideline: E6 Good Clinical Practice

Important identified risk, Important potential risk and Missing Information

An identified risk or potential risk that could impact on the benefit risk profile of the product or have implications for public health. What constitutes an important risk will depend upon several factors, including the impact on the individual, the seriousness of the risk, and the impact on public health. Normally, any risk that is likely to be included in the contraindications or warnings and precautions section of the product information should be considered important.

Missing information is gap/s in knowledge about a medicinal product, related to safety or use in particular patient populations, which could be clinically significant.

Modified from: ICH Harmonised Tripartite Guideline Periodic Benefit-Risk Evaluation Report (PBRER) E2C (R2) (Dec 2012).

Source: EU Guideline on good pharmacovigilance practices (GVP) Module V – Risk management systems (28 April 2014).

Immunization anxiety-related reaction

A range of symptoms and signs that may arise around immunization that are related to the stress around the procedure and not to the vaccine itself or the immunization programme, a defect in the quality of the vaccine or an error of the immunization programme. These reactions may include vasovagal-mediated reactions, hyperventilation-mediated reactions and stress-related psychiatric reactions or disorder.

Modified from: WHO Vaccine safety basics e-learning course, Module 3: Adverse events following immunization. (Webpage accessed 29 January 2022)

Immunization error-related reaction

An adverse event following immunization (AEFI) that is caused by inappropriate vaccine handling, prescribing or administration and thus by its nature is preventable.

Proposed by: CIOMS/WHO Working Group on Vaccine Pharmacovigilance.

Medication Error

A medication error is an unintended failure in the drug treatment process that leads to, or has the potential to lead to, harm to the patient. A failure in the drug treatment process does not refer to lack of efficacy of the drug, rather to human or process mediated failures.

Source: European Medicines Agency, Pharmacovigilance glossary, 18 August 2017

Pharmacovigilance

The science and activities relating to the detection, assessment, understanding and prevention of adverse effects or any other possible drug-related problems.

Source: The Importance of Pharmacovigilance: Safety Monitoring of Medicinal Products. Geneva, WHO, 2002.

Serious

A serious adverse event (experience) or reaction is any untoward medical occurrence that at any dose:

• results in death;
• is life-threatening;
• requires inpatient hospitalization or prolongation of hospitalization;
• results in persistent or significant disability/incapacity;
• is a congenital anomaly/birth defect.

Medical and scientific judgement should be exercised in deciding whether expedited reporting is appropriate in other situations, such as important medical events that may not be immediately life-threatening or result in death or hospitalization but may jeopardize the patient or may require intervention to prevent one of the other outcomes listed in the definition above. These should also usually be considered serious.

Source: Proposed by CIOMS Working Group IV.

Signal

Information on a new or known side effect that may be caused by a medicine and is typically generated from more than a single report of a suspected side effect. It is important to note that a signal does not indicate a direct causal relationship between a side effect and a medicine, but is essentially only a hypothesis that, together with data and arguments, justifies the need for further assessment.

Source: Uppsala Monitoring Centre (UMC). What is a signal?

Signal Detection

The act of looking for and/or identifying signals using event data from any source.

Proposed by CIOMS Working Group VIII.

Vaccine product-related reaction

An adverse event following immunization (AEFI) that is caused or precipitated by a vaccine due to one or more of the inherent properties of the vaccine product.

Proposed by: CIOMS/WHO Working Group on Vaccine Pharmacovigilance.

Vaccine quality defect-related reaction

An adverse event following immunization (AEFI) that is caused or precipitated by a vaccine that is due to one or more quality defects of the vaccine product including its administration device as provided by the manufacturer.

Proposed by: CIOMS/WHO Working Group on Vaccine Pharmacovigilance.

For the complete list of terms and definition, refer to the COIMS Cumulative Glossary, with a focus on Pharmacovigilance (Version 2.1).