Objective: Evidence from psychosomatic and nocebo research has indicated that believing one will develop symptoms makes the experience of such symptoms more likely. We applied this idea in the context of coronavirus disease 2019 (COVID-19). Specifically, we assessed whether beliefs regarding COVID-19 predict COVID-like symptoms 3-4 weeks later, and what specific belief has the greatest influence on symptom experience. Method: We conducted two studies with over 300 participants, approached at two successive timepoints, 3-4 weeks apart. Participants reported their experienced symptoms, COVID-19-related beliefs, demographics, and state anxiety. To target COVID-like symptoms, participants who reported having contracted COVID-19 or attributed their symptoms to another known cause were excluded. Regression analyses were conducted to test the predictive value of beliefs regarding COVID-19 on experienced symptoms. Results: A particular belief regarding one's estimated symptom severity if infected with coronavirus predicted the experience of symptoms 3-4 weeks later (β = .17, p = .011). This result persisted after controlling for potential confounds, including state anxiety (β = .22, p = .002). Findings were preregistered and replicated in a separate cohort. A novel scale for perception of the body's ability to fight diseases contributed to mediating the effect of estimated symptom severity on later experienced symptoms. Conclusions: A particular belief about estimated symptom severity if infected with COVID predicted the experience of COVID-like physical symptoms several weeks later. These findings contribute to the understanding of the development of unexplained physical symptoms. Furthermore, identification of a particular belief that increases the likelihood of symptoms informs intervention that may mitigate its effects.