What exactly is an endemic — and will the COVID-19 pandemic become one? An expert explains

As the continues on, a question has cropped up: Will the virus ever go away? Or, does this coronavirus have the potential to become endemic and stick around after this first outbreak ends?

While it feels like it’s been here forever, the virus has only existed globally for less than a year — so there are a lot of questions that remain unanswered, such as whether we can expect it to turn into an endemic disease or not, says , a PhD candidate in epidemiology at the Dalla Lana School of Public Health.

An endemic disease, Berry explains, is consistently present in the community, but at a stable and predictable level.

For endemic viruses, the R0 — the number of infections stemming from one sick person — is one, meaning that one infection leads to one more infection.

An example of this is influenza, which makes an appearance annually.

“It’s a predictable pattern. We see it every year,” Berry said. “It’s not this huge outbreak that’s uncontrolled.”

Diseases that become endemic are not necessarily endemic globally, Berry said. “For instance, malaria is endemic in parts of sub-Saharan Africa, but not here.”

Endemic viruses are always there, with immunity, spread interventions and seasonality all playing a role, Berry said.

An epidemic refers to regional outbreaks of viruses. A pandemic, on the other hand, is an outbreak that affects people globally. In both cases, a virus is surging beyond expected numbers, but only for a particular time period.

Berry pointed to the H1N1 outbreak in 2009 as an example of a pandemic that eventually turned endemic.

“At this point, we have H1N1 influenza seasons every couple of years,” she said.

That virus, also known as swine flu, “(has) a vaccine, we’re able to control it, we have an idea of when and how much it’s going to spread throughout the population. There’s an element of seasonality to it.”

It’s difficult to chart how COVID-19 will progress and how mitigating factors such as a vaccine may impact its spread in the future.

“There’s a little bit of uncertainty right now. We just haven’t had this disease around long enough to know that answer,” Berry said.

Jenna Moon is a breaking news reporter for the Star and is based in Toronto. Follow her on Twitter: