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The novel coronavirus that causes COVID-19 has quickly taken over our lives. As the global pandemic worsens, lockdowns across states and nations have gone into effect while hospitals in hard-hit areas remain in a state of constant crisis. As of March 27, over half a million people have been infected worldwide and deaths have topped 25,000. Those counts will increase greatly before the pandemic is over.

As we deal with the day-to-day realities of a worldwide disease, many of us are simply waiting for the pandemic to end. But there’s a worrying possibility lurking underneath the present crisis: COVID-19 might never go away.

There’s a very real chance the novel coronavirus could become endemic in the human population, much like influenza. If so, we could be living with COVID-19 for a long time.

But even an endemic coronavirus might not be reason to panic. There are too many unknowns right now for scientists to say whether we’ll see outbreaks similar in size and mortality to the current pandemic. As researchers around the world race to confront this new threat, we’ll surely know more soon.

The Virus You Know

There’s precedent for a coronavirus becoming endemic in the human population. Actually, there are four of them: 229E, NL63, OC43 and HKU1. All four of these coronaviruses cause symptoms of the common cold, and infections are most often fairly mild.

“We do know about other coronaviruses, it’s not like this is a virus that’s completely out of a new category,” says Amesh Adalja, a senior scholar at the Johns Hopkins Bloomberg School of Public Health’s Center for Health Security. “I think this will join those four other coronaviruses and have a similar pattern [of recurrence] after this first wave.”

As of right now, Adalja says, the novel coronavirus displays all the signs of sticking around. It’s widespread in the population, transmits from person to person easily and there’s no vaccine that could grant immunity ahead of an infection.

Uncertain Future

But there are still many unknowns that might affect how deadly recurring waves of COVID-19 might be. We don’t yet know, for example, how long someone remains immune to the novel coronavirus after an infection.

“The No. 1 thing we think about in terms of whether something is going to be endemic or whether it’s possible to eradicate it is whether immunity is permanent or long-lasting,” says Emily Toth Martin, an associate professor of immunology at the University of Michigan’s School of Public Health. “If you’ve got a virus where immunity can wane over time and someone can get reinfected, that is a very difficult virus for it to be eradicated.”

With the other four coronaviruses currently endemic in humans, we know that immunity disappears gradually over time — it likely takes years. Adults might get infected with the same virus they had as a child.

But even this kind of temporary immunity could be crucial in the short term. Doctors who have already been infected could treat patients without worrying about becoming sick. The same goes for other essential workers, like grocery store clerks, nursing home aides, delivery people and others.

And even if someone gets sick with the coronavirus again, the second infection might not be as bad. With other viruses, there’s evidence that, even if someone is reinfected, their immune system might be better equipped to handle it the second time around, Martin says.

A virus’ mutation rate is another important factor in determining the severity of reappearances of an endemic virus. The flu is so pervasive because it mutates readily, swapping around the surface proteins that our immune systems rely on to recognize viruses.

“You can get a new flu infection every year because your antibodies are not necessarily as protective,” says Andrew Brouwer, a research scientist and epidemiological modeler also at the University of Michigan’s School of Public Health. “We don’t really know what that’s going to look like for this virus.”

Another big unknown right now is when a vaccine will be available.

“This is something that’s going to be with us for some time, or for the foreseeable future, just like the other coronaviruses,” Adalja says. For that reason, “it’s incumbent upon us to make a vaccine to eliminate it as a threat.”

There are already four potential candidates for a coronavirus vaccine, as The Guardian reports. But it will be months, at least, before any vaccine is available to the public.

Looking ahead, vaccines will be an important part of our long-term strategy against COVID-19, Martin says.

“If I had to guess, I think that this is something that’s going to become part of the regular list of viruses that we monitor for all the time,” she says.

Dealing with the Unknown

In the absence of better knowledge about the novel coronavirus, governments need to focus on prioritizing surveillance of the disease, according to Martin. This includes making tests easy to distribute and carry out, something current regulations are inhibiting, she says.

While we don’t know the severity of successive waves of COVID-19, caution is warranted.

One paper, recently published in JAMA Cardiology , suggests that the coronavirus could be particularly deadly for those with high blood pressure and cardiovascular disease. If so, it could mean that COVID-19 might be deadlier than common colds or influenzas and will remain a lurking danger to humanity.

In the face of the unknown, all we can do is prepare.