Illness expectations predict the development of influenza-like symptoms over the winter season

Objective: This study explores the hypothesis that cognitive expectations of catching influenza-like symptoms increase the chances of developing the symptoms over the winter season. Design: Self-reported data from 247 healthy volunteers were obtained twice, before and after the winter season. In the first assessment, expectations about developing influenza-like symptoms in the incoming months were charted. This data was matched with a post-winter assessment of the actual development of the symptoms. Results: The odds of developing symptoms were highly associated with the expectations declared months before (OR = 1.776), and the association remained stable (OR = 1.453) even when accounting for previous influenza-like illnesses and the perception of general health. In contrast with previous findings, perceived stress was not associated with symptom development. Conclusions: These results support the hypothesis of a self-fulfilling prophecy mechanism related to influenza-like symptoms.