Coronavirus or COVID? A glossary to help navigate pandemic vocabulary

As scientific jargon and new words become prevalent in headlines, social media, and everyday conversations, Penn Today provides key definitions and context for making sense of COVID-19.

Word cloud consisting of words related to coronavirus
One impact to everyday life during the pandemic has been a flurry of new words and phrases entering the lexicon, including both scientific jargon as well as new phrases like “flatten the curve.”

Six months since a “pneumonia of unknown cause” was first reported to the World Health Organization (WHO), the novel coronavirus, along with the millions of patients infected and hundreds of thousands killed, has dominated news headlines, social media posts, and everyday conversations around the world. 

Alongside the many changes that the pandemic has brought, there has also been a flurry of new words and phrases entering into the lexicon. From scientific jargon that’s now commonplace to newly coined phrases to help leaders talk about the disease to their constituents, a lack of clarity about what all this new terminology means can dampen the ability to fully comprehend the situation. 

Penn Today shares a list of key definitions, along with some additional historical and scientific context, to help make sense of COVID-19. 

Virology 101

Virus: An infectious agent made of DNA or RNA inside of a protein envelope that can only grow and multiply by using the machinery of other cells. Because of this requirement, many scientists do not consider viruses to be living organisms. 

Coronavirus: A group of related viruses that can infect mammals and birds. When they were first discovered in the 1960s, the new family of viruses was called “corona” (Latin for “crown” or “wreath”) because the proteins that stick out from the surface resembled the Sun’s halo, known as the solar corona. In humans, coronaviruses cause diseases that can range from mild, like the common cold, to severe, like the Middle East respiratory virus.  

SARS-CoV-2: Severe acute respiratory syndrome coronavirus 2, the strain of coronavirus that causes COVID-19. It is sometimes referred to as a “novel coronavirus” because it has only been known since the end of 2019. A similar virus called SARS-CoV-1 was responsible for the 2002-04 SARS outbreak. Most viruses in this group only infect nonhuman species, with bats serving as a major reservoir. 

COVID-19: The disease caused by the virus SARS-CoV-2. The name comes from CO-rona-VI-rus D-isease along with the year it was discovered (2019). The official names of COVID-19 and SARS-CoV-2 for the disease and virus respectively were issued by the WHO on Feb. 11, 2020

Zoonotic disease: A disease caused by an infectious agent that can pass between humans and other animals. These diseases often appear suddenly and can be very harmful since they are unfamiliar to the human immune system. It’s estimated that 60% of known infectious diseases that affect humans come from animals, with examples including Lyme disease, malaria, and West Nile.  

Disease spread

Epidemic: The rapid spread of a disease to a large number of people above what is normally expected and within a short period of time. Recent epidemics include the spread of Ebola in Western Africa and the Zika virus epidemic in South and Central America

Pandemic: An epidemic that has spread across several countries and continents and affects a large proportion of the global population. Previous pandemics include the 2009 H1N1 pandemic and the 1918 influenza pandemic

Outbreak: The same as an epidemic but occurring over a more limited geographic area. One recent example is the 2019 New York measles outbreak, which impacted several neighborhoods in New York City. 

Community spread: When someone contracts a disease and the precise source of the infection cannot be found. During the early stages of the coronavirus pandemic, many of the patients who tested positive had a history of travel to affected areas or had contact with a known infected person. As more cases appeared that could not be explained, however, it signaled to public health officials that the disease was more widespread than initially thought, triggering school closures and cancellation of mass gatherings. 

Asymptomatic: A person that is not showing any signs of having a disease despite being infected. One particular challenge with the novel coronavirus is that individuals who don’t have symptoms can still spread the virus to others. This makes it difficult to slow the spread of the disease because people can unknowingly infect others before they feel ill.  

Droplet transmission: When bacteria or viruses travel within small drops of liquid from the respiratory tract. These droplets are produced by coughing, sneezing, singing, or talking and can be inhaled by or land on the mouth, nose, or eyes of a person nearby. Droplet transmission can be reduced by using personal protective equipment, including face masks, face shields, or goggles. 


Social distancing: Increasing the amount of physical separation between people to help prevent the spread of a contagious disease. The goal is to reduce the number of times that individuals come into close contact with others in order to reduce the likelihood that an infected person will transmit a disease. Examples of social distancing measures include closing schools, cancelling mass gatherings, and encouraging people to stay six feet apart in public spaces. 

a "flatten the curve" gif, with the number of cases on the x axis and time since first case on the y axis. a tall blue curve goes above a "healthcare system capacity" line while a wider yellow curve stays below the line
The blue curve shows what happens if no social distancing interventions are taken: a large number of people become infected within a narrow time frame. The yellow peak shows that, with an infection rate slowed by social distancing, new cases are spread over a longer period of time and the health care system is not overwhelmed. (Image: Siouxsie Wiles and Toby Morris from

“Flatten the curve”: A public health message used to illustrate the importance of social distance measures. Based on a paper published by the CDC in 2007, the “Goals of Community Mitigation” figure shows two bell-shaped curves representing the total number of daily cases over time. The taller curve shows what happens if no social distancing interventions are taken—a large number of people become infected within a narrow time frame. The flattened peak shows that, with an infection rate slowed by social distancing, new cases are spread over a longer period of time. Updated versions of the original graph have added a horizontal line indicating health care system capacity, illustrating how hospitals could become overwhelmed by a large number of cases if they all happen within a short period of time. 

Contact tracing: The process used by public health officials to identify people who have come in contact with someone with an infection. The goal is to test or monitor all of a patient’s contacts in order to track potential new infections and stop the spread of a disease by isolating those who are potentially infected. This process is typically done via interviews to learn about a patient’s movements and the people with whom they interacted. Follow-up calls reach those individuals at higher risk of infection to recommend isolation or testing. 

Lockdown: A measure imposed by a government that prevents people from leaving a region in an attempt to control a disease outbreak. This severe approach to infection control, used in Wuhan to reduce the spread of the novel coronavirus, is also referred to by the French term cordon sanitaire. One historical example of a cordon sanitaire is the 1793 yellow fever outbreak in Philadelphia, during which roads and bridges to the city were blocked by soldiers to prevent disease spread.  

Shelter in place: A mandate by government authorities to remain at home except for essential business, such as buying groceries or seeking medical care. To avoid confusion with more stringent orders of the same name, such as those enacted by governors during natural disasters, some have instead referred to these orders as “stay-at-home” or “safer-at-home” measures. 

Quarantine: The separation of people, animals, or goods to prevent the possible spread of infectious diseases. This idea of separating the ill from the healthy was well-understood during Biblical times but became more formalized in the Middle Ages. In 14th-century Italy, for example, ships arriving at Venice were required to wait 40 days before docking to ensure that passengers weren’t sick with the plague. The word for this practice is derived from the Italian quaranta giorni, meaning 40 days. 

Self-isolation/self-quarantine: Staying at home voluntarily to help prevent the spread of disease. 


Vaccine: A biological preparation that provides immunity to a specific infectious agent. The preparation is usually made of an inactivated or weakened version of a virus or bacteria, or only contains a portion of the agent that doesn’t cause disease. By stimulating the immune system to produce antibodies, a vaccine gives a person immunity to a disease without them having to contract it. 

Herd immunity: When enough people in a population are immune to a disease, either by recovering from a previous infection or receiving a vaccine, so that the disease no longer spreads easily. For COVID-19, some scientists estimate that 70% of the population would need to be immune to achieve herd immunity. 

Antibody: A protein produced by a component of the immune systems known as plasma cells to neutralize pathogens. Antibodies are created in response to a new infection and are specific to unique regions on a virus or bacteria. Having antibodies, however, does not mean that a person is immune. People who are HIV-positive, for example, have antibodies against the virus but are not able to clear the infection and can still transmit the disease to others.  

Any suggestions for additional words or phases to add to the list? Please contact Erica Brockmeier.