Will COVID-19 become endemic? Here's what that means

Ont. expanding COVID-19 restrictions CP24's Kayla Williams says York Region will join Toronto, Ottawa and Peel Region with a modified version of Stage 2 restrictions as of Monday.

TORONTO — No one knows when the pandemic will end, but one possibility is that COVID-19 never really goes away but becomes another endemic infectious disease that scientists learn to anticipate and control.

It’s a possibility explored in detail by Hans Heesterbeek, an epidemiologist with Utrecht University in the Netherlands, who calls it a “realistic scenario.” In a recent article for The Conversation, Heesterbeek pointed out that there’s little reason to believe a vaccine will immediately turn life back to normal, even when a safe option is made available.

Instead, it’s possible that the virus could eventually slow down due to immunity or vaccination, but never totally disappear. In this case, the coronavirus would continue to infect people at a “low, sometimes predictable rate,” Heesterbeek wrote, fitting the definition of an endemic.

Endemic diseases are illnesses that are anticipated and well understood, and doctors have the tools and know-how to manage such infections. For instance, chicken pox is endemic in North America, as is malaria in certain regions of Africa.

COVID-19 could be endemic only in certain parts of the world, and all it takes for the virus to keep spreading through populations is a sufficient number of people who remain susceptible to infection. These endemic infections could also follow a seasonal pattern, as is the case with other coronaviruses.

On a technical level, an infection is considered an endemic when each person with the infection passes it on to one other person. In an epidemic where cases are rising, this rate, known as the reproduction number, is greater than one.

Public safety measures, such as wearing a mask or physical distancing, are meant to reduce the reproduction number as low as possible in hopes of limiting the spread of the disease.

It’s important to note that immunity remains a major question mark in our current understanding of COVID-19. Scientists don’t know how long immunity lasts, though it’s believed to be many months. Researchers from the U.S. recently confirmed the country’s first case of re-infection, and some Canadian experts say reinfection may be more common than we think.

Other coronaviruses, such as the virus that causes a cold, provide only a fleeting layer of immunity, which is why it’s possible to catch a cold again and again.

If COVID-19 becomes endemic, the size of the outbreaks will depend on the effectiveness of treatments and vaccines. As Heesterbeek wrote, the virus will be manageable if doctors have the necessary medical tools at their disposal.

“COVID-19 will then be like several other diseases that we have learned to live with and many people will experience during their lives,” he wrote.

Under these circumstances, vaccines would play an important role. Annual coronavirus vaccines, similar to the flu shot, could be one possible solution, or a more lasting vaccine could be given to children with the possibility for booster shots.

Canada added more than 2,000 cases of COVID-19 on Tuesday as the country nears 20,000 active cases of the virus. Another 23 people died, according to national tallies.