The big question on everyone’s mind is: When will this nightmare end?

Dr. Bruce Aylward, the senior adviser to the Director-General of the World Health Organization (WHO), says the answer is complicated and depends on a number of factors.

Aylward with almost three decades of experience dealing with communicable diseases such as polio and Ebola, is in the forefront of fighting the current pandemic. In an interview with Time, he outlines the steps needed to stop the spread of the virus and what future measures need to be in place to prevent or control another outbreak.

He predicts that we should be emerging from the current crisis six months from now but with evidence of the disease still in many parts of the world.

“The challenge is we’re going to be back into the flu season,” he says. “And one of the big questions is, are we going to see a surge of it again at that period?”

Aylward doubts the coronavirus will ever disappear completely, but emphasizes that we do have some control over the severity of disease.

“A lot of it is going to depend on what we, as countries, as societies, do,” he says. “If we do the testing of every single case, rapid isolation of the cases, you should be able to keep the cases down low.”

While testing it critical, according to Aylward and WHO, the expert says he is “terrified” by the “sense of invulnerability of millennials,” and urges them not to underestimate the virus and their own responsibility to themselves and others.

According to Mark Jit, an infectious disease researcher at the London School of Hygiene and Tropical Medicine, in a recent article, the point of restrictions is to stretch out the pandemic even longer so that we don’t have a “big peak.”

“It’s not like a Hollywood movie with a clear ending where everyone is saved, or everyone dies,” he says, according to The Washington Times.

Despite the daunting task at hand, Aylward is optimistic for the future as long as we prioritize testing, isolating confirmed cases, and enforcing quarantines.

“This will end with humanity victorious over yet another virus, there’s no question about that,” he concludes. The question is how much and how fast will take the measures necessary to minimize the damage that this thing can do. In time, we will have therapeutics, we will have vaccines, we’re in a race against that.”