What Is an Endemic Virus? WHO Warns COVID-19 'May Never Go Away'

During a World Health Organization (WHO) press conference on May 13, 2020, Dr. Michael Ryan, executive director of the WHO's Health Emergencies Programme, doled out some sobering news to anyone looking for a specific end in sight for the COVID-19 pandemic: No one knows when it will end.

"We have a new virus entering the population for the first time, therefore it is very hard to predict when we will prevail over it," said Dr. Ryan. And as the pandemic continues, Dr. Ryan offered up another possible future scenario: That the virus may never fully leave us.

"It's important to put this on the table: This virus may become just another endemic virus in our communities, and this virus may never go away," said Dr. Ryan. Overall, Dr. Ryan said it's important to be realistic regarding the course of the COVID-19 pandemic: "I don't think anyone can predict when or if this disease will disappear," said Dr. Ryan.

What Exactly Is an Endemic Disease—and How Is It Different Than a Pandemic or Epidemic?

In epidemiology—the study of the distribution and determinants of health-related events in specified populations—there are different levels of disease. These levels, according to the Centers for Disease Control and Prevention (CDC), essentially measure how many people have gotten sick from a specific disease and how far it has spread:

• Sporadic: When a disease occurs infrequently and irregularly.
• Endemic: A constant presence and/or usual prevalence of a disease or infection within a geographic area. (Hyperendemic is a situation in which there are persistently high levels of disease occurrence.)
• Epidemic: A sudden increase in the number of cases of a disease—more than what's typically expected for the population in that area. (Similarly, an outbreak is in a more limited geographic area, and a cluster is an aggregation of cases grouped in place and time, suspected to be greater than usual.)
• Pandemic: An epidemic that has spread over several countries or continents, affecting a large number of people.

COVID-19, which was first identified in December 2019, quickly spread worldwide and was officially announced by the WHO as a pandemic on March 11, 2020. According to the CDC's definition of an endemic—and per Dr. Ryan's remarks in the May 13, 2020 press conference—COVID-19 could remain a constant presence, either around the world or in specific geographical locations.

In an April 2022 American Medical Association (AMA) article, Stephen Parodi, MD, an infectious diseases specialist with The Permanente Medical Group, stated that when COVID-19 moves from pandemic to endemic status, it will still be around, but won't be a constant disruption to our lives. "Endemic diseases can be at high levels. They can be at lower levels. So, where I think we're at a crossroads is that we have an opportunity to actually get that to a lower level, manageable level, where we're not getting impacted in our hospitals, not having to close down schools, close down businesses," said Dr. Parodi. "That really is through a combination of a concerted effort around testing, vaccination, isolation, quarantining, that looks a lot more normalized than what we've had to do over the last two years."

Dr. Parodi also stated that the fact that the CDC changed its primary focus in 2022 from the total number of positive cases to the number of hospitalizations—suggesting severe disease—shows that we're moving in the right direction. "This shift to looking at it from a severity of disease standpoint is important," said Dr. Parodi. "A measure of endemicity really is going to look at how many people are developing severe disease at a given time. If we're seeing increases in that, we've got to take action. If we're not, that's a different set of actions, and that's similar to what we do for influenza year over year."

What Are Some Examples of Endemic Viruses?

In the May 13, 2020 press conference, Dr. Ryan used human immunodeficiency virus (HIV) as a type of endemic virus. "HIV has not gone away but we've come to terms with the virus and we've found the therapies and we've found the prevention methods and people don't feel as scared as they did before," said Dr. Ryan, and added that now modern medicine is offering "long, healthy lives to people with HIV."

Malaria is another example of an endemic disease in certain areas, per the CDC. The highest transmission rate of malaria—a serious, sometimes fatal disease caused by a parasite and transmitted by mosquitos to humans—is in parts of Africa south of the Sahara, as well as regions like Papua New Guinea. Malaria is more prevalent in warm regions close to the equator, which is why travelers to those countries may need malaria prevention medications.

Ultimately, each of us has to determine our own level of risk regarding COVID-19, according to Anthony Fauci, MD, director of the National Institute of Allergy and Infectious Diseases (NIAID), in an April 10, 2022 ABC News interview. "So you're going to make a question and an answer for yourself, for me as an individual, for you as an individual. What is my age? What is my status? Do I have people at home who are vulnerable that if I bring the virus home there may be a problem?" said Dr. Fauci.

Dr. Fauci stressed that COVID-19 "is not going to be eradicated and it's not going to be eliminated." But it is, however, just a matter of time before it becomes endemic.

The information in this story is accurate as of press time. However, as the situation surrounding COVID-19 continues to evolve, it's possible that some data have changed since publication. While Health is trying to keep our stories as up-to-date as possible, we also encourage readers to stay informed on news and recommendations for their own communities by using the CDC, WHO, and their local public health department as resources.