Glossary

Presenting no symptoms of a disease. In the case of COVID-19, this means the absence of fever, dry cough, sore throat, shortness of breath, and body aches, among other less common symptoms. Notably, it is recommended that individuals do not get tested unless they exhibit symptoms because of the risk of false negatives. In other words, most tests will not be accurate unless symptoms are present.

When researchers study a medical test or treatment in a set group of people to make sure it’s safe and effective before giving it to the public.

Someone who has been within 6 feet of an infected person (laboratory-confirmed or a clinically compatible illness) for a cumulative total of 15 minutes or more over a 24-hour period (for example, three individual 5-minute exposures for a total of 15 minutes in one day). An infected person can spread SARS-CoV-2 starting from 2 days before they have any symptoms (or, for asymptomatic patients, 2 days before the positive specimen collection date) until they meet the criteria for discontinuing home isolation.

A family of related viruses. Many of them cause respiratory illnesses. Coronaviruses cause COVID-19, SARS, MERS, and some strains of influenza, or flu. The coronavirus that causes COVID-19 is officially called SARS-CoV-2, which stands for severe acute respiratory syndrome coronavirus 2.

According to experts, herd immunity is a term used to describe the slowing of disease spread that occurs “when a significant portion of a population becomes immune to an infectious disease.” Herd immunity limits the spread of disease. It can protect people in a community who are not immune if enough individuals are immune to the infection.

Your body’s ability to resist or fight off an infection. Your immune system is a network of cells throughout your body that helps you avoid getting infected and help you get better when you are infected.

MRNA vaccines teach our cells how to make a protein — or even just a piece of a protein — that triggers an immune response inside our bodies. The benefit of mRNA vaccines, like all vaccines, is those vaccinated gain protection without ever having to risk the serious consequences of getting sick with COVID-19.

Occurring over a wide geographic area and affecting an exceptionally high proportion of the population.

The separation of a person or group of people reasonably believed to have been exposed to a communicable disease but not yet symptomatic from others who have not been so exposed to prevent the possible spread of the communicable disease. Quarantine may be voluntary or compelled by federal, state, or local public health order.

A preparation that is administered (as by injection) to stimulate the body’s immune response against a specific infectious disease.