Background: The current situation in schools in relation to COVID-19 may generate a decrease in the academic performance of students. This decline could be the consequence of factors extrinsic (organizational measures adopted by schools) and intrinsic to students (cognitive regulation of emotions). In relation to intrinsic factors, an increase in ruminant thoughts about COVID-19 could interfere with the attention of students, which would have as a consequence a decrease in their academic performance. In a context in which concern about COVID-19 has occupied many spheres of our lives, including the academic context, it is essential to analyze what personal factors contribute to increasing or decreasing our dysfunctional thoughts. Therefore, the objective of this study was to explore the relationship between the perception of vulnerability to the disease and ruminant thoughts about COVID-19. Method: From a cross-sectional sample of post-compulsory education students, the relationship between the different dimensions of perception of vulnerability to the disease and ruminant thoughts was analyzed, measured with a modified version of the rumination subscale of the cognitive emotion regulation questionnaire. Results: The data suggest that the level of ruminant thoughts in students is medium or high (M = 3.14; SD = 1.13). Additionally, there is a positive relationship between the perception of vulnerability to the disease and ruminant thoughts about COVID-19 (r = .23). Furthermore, it is possible to predict the level of ruminant thoughts about COVID 19 based on the perception of vulnerability to the disease (y = 1.67 + .46X; β = .46, p <.05; 95% CI [. 07 .83]). Conclusions: our findings are consistent with the current understanding of the role of perception of vulnerability to illness and dysfunctional thoughts. Adopting organizational measures that offer security to students against the possibility of being infected by COVID-19 could avoid an excess of ruminant thoughts and, as a consequence, less interference with attention.