“The word ‘endemic’ has become one of the most misused of the pandemic,” wrote Aris Katzourakis, a professor who studies viral evolution and genomics at Oxford University, in his recent Nature article. “And many of the errant assumptions made encourage a misplaced complacency. It doesn’t mean that COVID-19 will come to a natural end.”
Katzourakis explains that when an infection is endemic, it means that the overall rates of infection are static—it continues to infect and kill but doesn’t grow significantly—not that it is no longer dangerous or deadly. This becomes more obvious when we examine currently endemic diseases such as malaria, tuberculosis, and polio.
“Malaria killed more than 600,000 people in 2020. Ten million fell ill with tuberculosis that same year and 1.5 million died,” wrote Katzourakis. “Endemic certainly does not mean that evolution has somehow tamed a pathogen so that life simply returns to ‘normal.’”
And endemicity holds no promise in terms of viral stability either. Even if SARS-CoV-2 becomes endemic, that does not stop the virus from continuing to evolve, resulting in new variants—variants that could be even more dangerous than those we’ve seen in recent months, such as Delta and Omicron, and that could cause a large wave of new infections, “as seen with the US measles outbreak in 2019,” wrote Katzourakis.
Our fate in terms of COVID-19 is in our hands, endemic or not, writes the evolutionary biologist. There is a direct link between our response to the situation and its outcome: “The same virus can cause endemic, epidemic, or pandemic infections: it depends on the interplay of a population’s behavior, demographic structure, susceptibility and immunity, plus whether viral variants emerge.
“Different conditions across the world can allow more-successful variants to evolve, and these can seed new waves of epidemics.”
By “different conditions,” Katzourakis means the different responses and public health policies of each region. Omicron is the most recent example of this. It emerged at a local level, but without robust public health measures and limited access to vaccines in Africa, it rapidly spread across the globe.
Thus, it’s clear that public health measures will still be important, even when we reach endemicity, to prevent the spread of new variants. In particular, he highlights the importance of improving our understanding of how to stop the spread of airborne pathogens and continuing to develop effective vaccines, antiviral medications, and of course, diagnostic tests.
“Thinking that endemicity is both mild and inevitable is more than wrong, it is dangerous: it sets humanity up for many more years of disease, including unpredictable waves of outbreaks,” concludes Katzourakis.