The novel coronavirus SARS-CoV-2 is often compared to its close genetic cousin SARS-CoV-1. And for good reason: The virus responsible for the early 2000s SARS outbreak is, in many ways, the closest parallel to what we’re dealing with now. Researchers look to it when studying how long the new virus survives on surfaces and whether it makes sense for us to wear masks. It provides a guide for how the curve of cases and deaths might bend if we all do our part and stay home. The comparison offers some hope: Social distancing and travel restrictions helped squash the SARS outbreak in about a year.

But that kind of sweeping containment has begun to look far less plausible. To predict the long-term course of Covid-19, a different analogy may be in order. What if the virus is more like some of its lesser-known family members, like HCoV-OC43 and HCoV-HKU1? The names are not as familiar, but you’ve likely met them before. These viruses cause the common cold. And while they’re less deadly than SARS or MERS, they’re peskier too; they come and go with the seasons, with human immunity waning over time. It’s why we keep catching them, again and again.

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A paper published Tuesday in Science by Harvard University public health researchers explores that possibility, and what it would mean for Covid-19’s spread in the long term. Their conclusions are somewhat grim. If SARS-CoV-2 follows in the footsteps of these cold germs, herd immunity will be slower to build up and hold. (Herd immunity occurs when enough members of a population have either already had a disease or been vaccinated against it, stopping the flow of its transmission.) Until that happens, outbreaks would be a regular fact of life. Combined with the virus’s greater severity, that would require social distancing interventions to happen again and again, to avoid overwhelming hospitals each time.

The Harvard researchers found we could be looking at being shut-ins, at least from time to time, for a long while—think 2022.

The role of seasonality “is certainly not zero,” Marc Lipsitch, a professor of epidemiology at Harvard who coauthored the study, said at a press conference held Tuesday. He cautioned that seasonal variability is not the same thing as saying the virus will go away in the summer. Outbreaks could occur at any time, he noted, but those that begin in the fall might be more severe. That kind of variation could have important implications for how social distancing measures are timed.

Whether Covid-19 will mirror the transmission of coronavirus-caused colds is far from certain, the researchers acknowledge. The virus has been around for only a few months, so no one has been able to directly study how it spreads during different seasons. We also don’t yet know how well immunity builds up, and how long it lasts once established. The Harvard team’s models also depend in part on the rather bleak assumption that the scientific community won’t develop treatments or vaccines that dull the virus’s toll on health systems. All that could change, the researchers say.

In the absence of hard data about SARS-CoV-2, the cold-causing coronaviruses are useful for making long-term comparisons, says Ashleigh Tuite, an epidemiologist at the University of Toronto who wasn’t involved in the study. “Are they going to be the same as SARS-CoV-2? Probably not. It’s a different virus,” she says. “But it’s probably the best analogy that we have to work off of right now, especially thinking longer term.” The paper does a good job outlining the uncertainties, she adds. It does what models do: helps us prepare for the unknown.