It can take years for scientists to determine endemic patterns while pandemics settle, and consequences of widespread illness can be long lasting after new infections fade, leaving the endemic stage of COVID-19 a "mystery," The New York Times reported April 7.
"There’s been a political reframing of the idea of endemic as something that is harmless or normal," Lukas Engelmann, a historian of medicine and epidemiology at the University of Edinburgh, told the Times.
Mr. Engelmann added that epidemiologists use the term for conditions that should be watched carefully, as endemic diseases have the potential to become epidemics again.
Many scientists predict the endemic stage of COVID-19 will be similar to other respiratory viruses, but the burdens of endemic diseases are "unequal," according to experts who spoke with the Times, as communities' experiences with diseases often differ.
"It will be no more deadly than seasonal flu or may be mild like one of the cold-causing coronaviruses," Lone Simonsen, the director of the PandemiX Center at Roskilde University in Denmark, told the Times.
Immunity from vaccination and infection may wane over time, and the random mutation of future variants may cause severe disease.
One thing is certain, according to the Times: A disease making the transition to an endemic state does not indicate the end of that disease. Countries must use control measures, such as testing and vaccinations, to keep diseases from becoming epidemics again.