WHO predicts COVID-19 will become endemic, but some experts are less certain

World Health Organization officials are predicting that the "destiny" of the COVID-19 virus is to become endemic, suggesting it could continue to spread through the population at a steady rate despite a global vaccination effort.

But some Canadian scientists say the future of the novel coronavirus is far from set in stone, noting there are a variety of factors that could shape the trajectory of the infectious disease.

At a news conference Tuesday, several senior WHO officials warned that the development of COVID-19 vaccines is no guarantee that the virus will be eradicated, proposing that a more realistic goal would be to reduce the threat of transmission to more manageable levels.

"It appears at present that the destiny of SARS-CoV-2 (the virus that causes COVID-19) is to become endemic," said David Heymann, the London-based chair of the WHO's strategic and technical advisory group for infectious hazards.

"But its final destiny is not yet known. Fortunately, we have tools to save lives and these in combination with good public health ... will permit us to learn to live with COVID-19."

According to the U.S.-based Centers for Disease Control and Prevention, a disease is endemic when it is constantly or predictably prevalent within a population or region. For example, chickenpox is endemic in much of North America, spreading at a steady rate among young children.

Dr. Gerald Evans, chair of the infectious diseases division at Queen's University in Kingston, Ont., agrees that the COVID-19 virus is on track to follow several other human coronaviruses that have become endemic, most often causing mild respiratory symptoms, such as the common cold.

Evans said some evolutionary biologists believe that after making the jump from animal to human populations, these endemic coronaviruses mutated over centuries to strike a pathogenic balance between ensuring effective transmission from person to person, without being so virulent as to kill off the host.

He projects that the COVID-19 virus could follow a similar evolutionary path, but said this process could be compressed over a shorter period of time because "vaccine-induced herd immunity" would limit the pool of potential hosts to favour more transmissible but less virulent versions of the disease.

"We can speed up the process of adapting the population to the new virus by using vaccines ... so that we don't have to wait 100 years for this to become a sort of low-grade endemic coronavirus that causes a cold-like syndrome in wintertime around the world."

But Jean-Paul Soucy, a doctoral student in epidemiology at University of Toronto, says that while the COVID-19 virus doesn't seem to be going away any time soon, there are too many unknowns to predict what the disease will look like down the line.

"I think it's fair to say that (the COVID-19 virus) will continue to exist somewhere in the world for the foreseeable future," Soucy said. "But how much it will directly impact us remains to be seen."

While some pathogens mutate to become less lethal, Soucy said that's not the case for every virus.

The piecemeal distribution of COVID-19 vaccines across the globe will likely influence the geography of the disease, said Soucy.

Moreover, he said, it's still unclear whether the first batch of vaccines will stem the spread of the virus, or just prevent the development of symptoms.

With so many questions remaining, Jason Kindrachuk, a virologist at the University of Manitoba, maintains that the possibility that the COVID-19 virus will become endemic is not a "forgone conclusion."

"I know it's bleak right now," said Kindrachuk. "But certainly, this is not the first time that that populations have been in this situation."

Vaccinations campaigns have eradicated viruses in the past, he said, pointing to the decades-long effort to eliminate smallpox.

It's difficult to say whether that's possible for COVID-19, said Kindrachuk, given that the virus is believed to have jumped from animals to humans, and there's always the potential for additional cross-species "spillover."

But Kindrachuk worries that overconfident predictions that COVID-19 is here to stay could breed complacency among a pandemic-weary public, when Canadians should be working towards the ultimate goal of stopping the spread of the virus.

"We can't resign ourselves to a particular outcome at this point," Kindrachuk said. "We still have a lot of the outcome in our hands."

This report by The Canadian Press was first published Dec. 30, 2020.