ORLANDO, Fla. – As the world works to vaccinate millions of people to put an end to the coronavirus pandemic, there are a series of terms that continue to pop up as more vaccine candidates get closer to emergency use approval.
To help sort through information regarding available vaccines and those still in trial, here are a few terms and definitions to know about.
The Centers for Disease Control and Prevention defines active immunity as the production of antibodies against a specific disease by the immune system. This type of immunity can be achieved in two ways: either by contracting the disease or through vaccination.
Active immunity is usually permanent, according to the CDC. This means a person is protected from the illness or disease for the rest of their lives.
This is defined as any health problem that happens after a shot or other vaccine, according to the CDC. It’s a scientific way to describe a potential reaction after getting a vaccine. These events might be caused by the shot or a coincidence, especially if the person receiving the injection has other pre-existing health conditions.
A protein found in the blood that is produced in response to a foreign substance such as a bacteria or virus in the body. During the pandemic, antibodies are often referred to in relation to COVID-19. Antibodies typically protect the body from the virus by binding to these organisms and destroying them.
Note, not everyone who contracts COVID-19 will build antibodies.
Approval (emergency use authorization)
In the United States, drugs, vaccines and medical devices can’t be sold without gaining approval from the Food and Drug Administration. This is also called licensure.
After a company submits data from its clinical trials for consideration, the FDA will determine if the product is safe and note if it’s effective.
In the wake of an emergency such as the coronavirus pandemic, companies can instead apply for emergency use authorization, according to the FDA. These authorizations are quicker but often means the product is still experimental.
Community immunity (herd immunity)
This is a threshold in which a sufficient proportion of a population is immune to a disease. This is also called herd immunity.
Community immunity is often achieved through vaccination or after a community has built immunity through prior illness, according to the CDC. This threshold means the spread from person to person is unlikely.
The CDC notes 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.
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This describes how good a vaccine is at preventing disease.
During a clinical trial, this is often referred to as the benefit of the vaccine versus the placebo. During coronavirus vaccine trials, researchers compare how many people in the vaccinated and placebo groups contract the virus.
Efficacy is different from effectiveness, the CDC notes. Effectiveness often refers to the benefit a drug provides society, outside of clinical trial. Effectiveness could be lower or better than its efficacy once put to wider use.
Phase 1,2 and 3 trials
These describe the typical stages of a clinical trial.
Phase 1 usually involves a few volunteers to test a drug and they’re observed to see if it’s safe.
Phase 2 trials expand to include hundreds of people, giving researchers the flexibility to test different doses, according to the FDA.
Phase 3 involves thousands or tens of thousands of volunteers. This is the stage where researchers determine efficacy and whether a drug is safe. Companies can apply for drug approval with the FDA after completing this phase.
Though uncommon, waning immunity is the loss of protective antibodies over time. Researchers are keeping an eye on this as the globe learns more about the novel coronavirus.