Reference
Glossary
Plain-language definitions of the terms used across OSMF sites. The same definitions power the dotted-underline tooltips in research notes and on the Vaccine Data Navigator.
Plain-language definitions of the terms used across OSMF sites. The same definitions power the dotted-underline tooltips in research notes and on the Vaccine Data Navigator.
How often a condition occurs in a population anyway, which is what any count of events after a vaccine or drug has to be compared against.
A structured judgement, using criteria such as timing, dose and alternative explanations, of how likely it is that a product caused a reported event.
A set of statistics (such as the PRR and ROR) that asks whether an event is reported unusually often for a product compared with the rest of a reporting database.
The European Medicines Agency's database of suspected side-effect reports for medicines authorised in the European Economic Area.
The US FDA Adverse Event Reporting System for medicines and biologics; like VAERS it collects voluntary reports, so counts reflect reporting, not rates of harm.
A single production run of a vaccine or medicine identified by a code on the packaging; report counts per lot are not comparable unless you also know how many doses of each lot were given.
A safety system that waits for people to send in reports rather than actively following a defined group, which makes it good at spotting possible signals and poor at measuring how often they happen.
The science of detecting, assessing and preventing side effects of medicines and vaccines once they are in use.
Proportional reporting ratio: how much more often an event is reported for one product than for all others in the same database, used to flag signals, not to measure risk.
A reminder that a count of adverse-event reports has no denominator, so it cannot tell you how often an event happens per dose or per person.
Reporting odds ratio: a disproportionality statistic similar to the PRR that compares the odds of an event being reported for one product against all others.
A pattern in reports that suggests a possible link between a product and an event and that needs further study before it can be called a cause.
The US Vaccine Adverse Event Reporting System: a passive database where anyone can report a health problem after vaccination, so a report records that something was noticed, not that the vaccine caused it.
Something measurable in the body, such as a blood protein or imaging finding, that indicates a biological state or disease process.
A public database of drug-like molecules, their biological targets and measured activities, maintained by the European Bioinformatics Institute.
An association between a compound or target and a disease reported in the literature, without a demonstrated cause or clinical effect.
The Drug–Gene Interaction Database, a public resource that lists which drugs are known to act on which genes, with the papers behind each link.
Testing a medicine that is already approved for one condition to see whether it also helps with a different one.
A gene or protein involved in a disease that an existing or feasible medicine can act on.
Evidence that a compound acts on a target in a laboratory or animal model, which shows how it could work but not that it helps patients.
A public platform that scores the evidence linking genes to diseases from genetics, literature, animal models and drug data.
A detailed description of one patient or a small group, which can raise a question but cannot show how common or how causal a finding is.
Digital Object Identifier: a permanent code for a publication that always resolves to its current location online.
A statistical pooling of results from several studies of the same question to produce one combined estimate.
An expert overview of a topic that summarises selected studies without a pre-registered search method, useful for context but open to selection bias.
A study that follows or compares groups of people as they are, without assigning treatments, so it can show associations but struggles to prove cause.
Published so that anyone can read it free of charge, usually under a licence that also allows reuse.
Evaluation of a paper by independent experts before a journal publishes it, which filters out some errors but does not guarantee the findings are correct.
A research paper posted publicly before it has been peer reviewed, so its findings have not yet been checked by independent experts.
A free search engine from the US National Library of Medicine that indexes biomedical research papers.
Randomised controlled trial: participants are assigned by chance to a treatment or a comparison group, which is the strongest single-study design for showing that a treatment works.
A review that searches for every relevant study using a pre-defined method and appraises them together, rather than selecting studies informally.
A clinical trial run largely from participants' homes using remote visits, local labs and shipped medication rather than a central hospital site.
The identifier a trial receives when it is registered on ClinicalTrials.gov, which lets you read its design, status and sponsor at the source.
An inactive comparison treatment that lets a trial separate the effect of a medicine from the effect of being treated and observed.
A registered trial that is currently enrolling participants; it says the treatment is being studied, not that it works.
Clinical trials move from Phase 1 (safety in a few people) through Phase 2 (early signs of effect) and Phase 3 (large comparison against standard care) to Phase 4 (monitoring after approval).
A chemical that interferes with the body's hormone system, for example by mimicking or blocking a hormone.
Symptoms that persist or appear weeks to months after a SARS-CoV-2 infection; also called post-acute sequelae of COVID-19 (PASC).
Mast cell activation syndrome: episodes of allergy-like symptoms caused by mast cells releasing their contents too readily.
Myalgic encephalomyelitis / chronic fatigue syndrome: a long-term illness marked by profound fatigue and worsening after exertion, often following an infection.
Post-acute COVID vaccination syndrome: a proposed term for persistent symptoms that begin after COVID-19 vaccination, still under study and without agreed diagnostic criteria.
Postural orthostatic tachycardia syndrome: an abnormal rise in heart rate on standing, with dizziness and fatigue, that often appears after an infection.
The process by which cells burn fatty acids for energy, one of the metabolic pathways studied in post-viral fatigue.
A tiny fat-based capsule used to protect mRNA and carry it into cells.
Messenger RNA: the molecule cells use as a working copy of a gene to make a protein; mRNA vaccines deliver a synthetic copy that instructs cells to make a viral protein.
The surface protein SARS-CoV-2 uses to enter cells, and the protein that COVID-19 vaccines instruct the body to produce to train an immune response.
Definitions are deliberately short and non-technical. Where a term has a precise regulatory or statistical meaning, the linked source on the page that uses it is authoritative. Spotted an error? Tell us. Research information, not medical advice.