A key unsolved question in the current coronavirus disease 2019 (COVID-19) pandemic is the duration of acquired immunity. Insights from infections with the four seasonal human coronaviruses might reveal common characteristics applicable to all human coronaviruses. We monitored healthy individuals for more than 35 years and determined that reinfection with the same seasonal coronavirus occurred frequently at 12 months after infection. The durability of immunity to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is unknown. Lessons from seasonal coronavirus infections in humans show that reinfections can occur within 12 months of initial infection, coupled with changes in levels of virus-specific antibodies.