From Johns Hopkins Bloomberg School of Public Health:
Two main clues help us predict whether a virus is going to stick around. First, we consider the virus’s origins. If it came from animals and could still be circulating in animals, then no matter how good we are at getting rid of it in humans, animals could always bring it back. That’s true with influenza: Even if a certain strain disappears, a new one might emerge from animals—as we’ve seen with avian viruses.
But with a major outbreak like COVID-19 already underway in humans, the big question is how good humans are at developing immunity. And, if they gain immunity, does it stick, or does it fizzle out over time—leaving the door open a crack for the virus to return? As the first cases get further and further out from the point of infection, that data will give us a better idea of what to expect.
Emily Toth Martin, PhD, MPH, is an associate professor of epidemiology at the University of Michigan School of Public Health.