Glossary
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| Term | Definition |
|---|---|
| Vaccine Safety Datalink | A collaboration between the CDC and several U.S. health care organizations that uses electronic health records to monitor vaccine safety and study possible adverse events. Vaccines |
| Vaccine schedule | See immunization schedule: the recommended timing of vaccines by age. Vaccines |
| Vaccine Shedding | Release of vaccine-derived virus from a person given a live attenuated vaccine, such as oral polio vaccine. Non-live vaccines, including mRNA vaccines, cannot shed. Vaccines |
| Vaccine-derived poliovirus | A rare strain of poliovirus that has mutated from the weakened virus in the oral polio vaccine and can spread in under-vaccinated communities. Higher vaccination coverage prevents it. Vaccines |
| Vaccine-preventable disease | An infectious disease for which an effective vaccine exists, such as measles, polio, pertussis, and hepatitis B. Vaccines |
| VAERS | The US Vaccine Adverse Event Reporting System, an open early-warning database. Anyone can submit a report, and reports are unverified, so raw counts do not show that a vaccine caused an event. Vaccines |
| Valency | The number of different strains or types a vaccine protects against. For example, a quadrivalent flu vaccine targets four strains. Vaccines |
| Validation | Checking the accuracy of something. For example, to validate a climate model, scientists run the model to ?predict? the weather patterns over the past 20 years. Then they compare the output with the actual measurements and observations we have collected for that time. Science General |
| Validation set | Data held back from training and used to tune a model and check for overfitting. Artificial Intelligence |
| Variable | In scientific or mathematical models, a factor whose value may vary (e.g., average air temperature, amount of solar radiation, etc.) Science General |