We know much more about COVID-19 than we did at the beginning of the pandemic, yet this coronavirus continues to shape the scientific, social, and political landscape in new and unexpected ways. With each pandemic phase, novel language and phrases emerge for everything from testing to treatments.
Penn Today shares a fourth update to its COVID-19 glossary, building on the first, second, and third installments to address developments in research, medicine, and epidemiology. Though some of the following terms may apply to other viruses or public health scenarios, this glossary focuses solely on their definitions as they relate to the coronavirus pandemic.
Testing and treatments
Viral load: The amount of virus in an individual’s body. A person’s viral load doesn’t always correlate with how sick he or she feels; an individual with low viral load can still feel quite ill, and vice versa.
Viral load is an important factor for transmissibility and testing. People with lower viral loads are less contagious and less likely to test positive on an antigen or PCR test.
False negative: When an individual who has COVID-19 tests negative for the virus. False negatives can occur for a variety of reasons, including testing too early in the course of the illness, having a low viral load, or administering the test improperly.
Because rapid tests commonly result in false negatives, experts now advise people exhibiting COVID-19 symptoms but who test negative on a rapid antigen test to confirm their results with a PCR test.
False positive: When someone who does not have COVID-19 tests positive for the virus. False positives are relatively rare, occurring in fewer than 1% of rapid tests.
Drive-through testing: A type of testing now offered by many pharmacies where people can quickly take an antigen or PCR test from their car.
Antiviral therapies: Treatments for COVID-19 that stop the virus from replicating in a person who has been exposed. The NIH recommends administration of antivirals as early as possible to prevent severe illness and hyperinflammation.
Remdesivir is currently the only FDA-approved antiviral therapy to treat COVID-19. The drug stops COVID-19 from reproducing in the body by hijacking the enzymes the virus uses to copy its genetic material. Remdesivir, primarily given to hospitalized patients, is administered intravenously.
Paxlovid is an oral antiviral pill granted emergency use authorization by the FDA. The pill, known generically as Nirmatrelvir and Ritonavir, can be taken at home and used to prevent severe illness in high-risk patients.
Monoclonal antibodies are lab-made molecules that mimic natural antibodies the immune system produces. Most target the virus’s spike protein to block it from attaching to cells. However, because the spike proteins in different variants differ slightly, the effectiveness of monoclonal antibodies can fluctuate from variant to variant. The CDC recommends monoclonal antibodies for non-hospitalized people with mild to moderate COVID-19 who aren’t at high risk of developing severe disease.
Convalescent plasma therapy uses blood plasma donated by people who have recently recovered from COVID-19. Because the donated plasma contains antibodies that can fight the virus, convalescent plasma can help decrease viral replication. As of July 2022, convalescent plasma therapy is available under an emergency use authorization for immunosuppressed patients only.
Surge: A sustained increase in the number of COVID cases in a community. The most recent major surge driven by the immune-evading omicron variant ended in February 2022 but epidemiologists warn of a new summer surge driven by the omicron subvariant BA.5.
Epidemiologists use statistical methods to model case numbers and track surges. One confounding factor that can upend those statistical calculations is the discrepancy between recorded cases and actual cases.
Recorded cases: The number of confirmed coronavirus cases reported to a doctor or a public health agency. Due to the rise of at-home rapid testing, many positive test results now go unreported.
Actual cases: The true number of people who have coronavirus. This number is difficult, if not impossible, to know exactly. Individuals may be asymptomatic, never test for COVID-19, or not report their positive tests, so epidemiologists must account for all such factors when estimating case count.
Waning immunity: A phenomenon in which the immune system’s defenses against COVID-19 fade over time. Vaccination and infection both provide temporary protection against the coronavirus, but that decreases over the course of months. However, immunity isn’t reset back to zero; while levels of the frontline fighter antibodies start to decline a few months after vaccination or infection, longer-lasting T and B cells remain to defend against COVID.
Bivalent vaccines: New mRNA vaccines in development that protect against the original strain of the virus and the omicron variant. The jury is still out on whether these redesigned versions of the vaccine will provide significantly better protection against COVID-19 than the vaccines already in use, but, if research proves them more effective, they may be the frontrunners for fall booster shots.
Reinfection: When an individual catches COVID-19 again after an initial infection. Repeat infections can occur with the same variant but are more likely when a new variant emerges that evades the body’s existing immune defenses. Experts recommend staying up to date on boosters and following public health measures to help lower the risk of reinfection.
Zero-COVID policy: A strict pandemic strategy whose goal is zero COVID cases. This stringent policy has resulted in near-total lockdowns in the face of spiking case numbers in major cities like Shanghai. Though such a policy may keep case numbers down in the short term, some experts have argued that the strategy is unsustainable in the long run; total lockdowns in major Chinese cities, for example, have exacerbated supply-chain issues sparked by the pandemic.
U.S. public health officials have shifted toward a strategy that encourages people to make behavioral adjustments, such as masking or social distancing, based on community and individual risk. The CDC advises people to choose which pandemic safety measures they employ by considering their COVID-19 community levels and determining whether they or someone they spend time with is high risk or immunocompromised.
Community levels: Risk levels provided by the CDC that give a general summary of the amount of COVID-19 transmission within a county. Community levels factor in case numbers and hospital admissions and will indicate either low, medium, or high risk of COVID-19 transmission.
High-risk individuals are people especially likely to contract COVID-19 or experience a severe case should they get COVID-19. Age is one of the biggest factors—adults 85 and older are most at risk of serious COVID-19 symptoms—but other factors, including obesity, diabetes, and heart or lung conditions, contribute to the possibility of developing severe symptoms.
Immunocompromised people have a weakened immune system. Being immunocompromised is an indicator of high COVID-19 risk. Organ transplants, cancer treatment, and HIV/AIDS can all cause a weakened immune system. Not everyone at high risk of getting COVID or having a serious case is immunocompromised, but everyone who is immunocompromised is high risk.
Long COVID: Also referred to by the CDC as post-COVID conditions, this recently recognized syndrome comprises symptoms such as fatigue, shortness of breath, and cognitive dysfunction that persist for longer than three months after a COVID-19 infection. These symptoms may occur as a continuation of the initial infection or appear on their own.
Though long COVID is more common in people who experienced severe initial illness, it can affect anyone, even those with asymptomatic initial infections. Vaccination helps protect against long COVID but does not fully prevent it.
Brain fog: The short-term memory loss, confusion, and difficulty concentrating from which many long COVID patients suffer. Brain fog can clear up on its own, but long COVID patients have reported experiencing it for a year or longer.
Pandemic fatigue: Apathy toward COVID-19 and a demotivation to follow public health guidelines that has developed after years of dealing with the coronavirus. Psychologists say this lapse in motivation is a normal response to years of living in crisis mode and confronting difficult decisions, but public health officials urge citizens to continue following pandemic guidelines.
Health care worker burnout: The phenomenon in which frontline health care workers become overwhelmed, physically and emotionally drained, and exhausted. Many have left their jobs in the wake of the pandemic, leading to a health care worker shortage that has only exacerbated burnout.