Studies suggest that sterilizing immunity from garden-variety coronaviruses only lasts on the order of months for most people, leaving them
open to reinfection after a year or so. That’s how those school-yard coronaviruses—dubbed 229E, NL63, OC43, and HKU1—come around every cold and flu season. After decades of circulating, they mostly hit young children, who haven’t yet built up immunity from previous seasons. In adults who have those years of immunity, the coronaviruses generally cause only trifling cold symptoms.
As mentioned before, some experts think SARS-CoV-2 will reach this same fate—eventually. We have to build up immunity in adults first. But it’s possible that people infected with SARS-CoV-2 at the beginning of the pandemic may become vulnerable to reinfection in the near future, before they can have their immune responses boosted by a vaccine. And that may mean more surges of disease before we get to those schoolyard sniffles.