The first cases of COVID-19 in Mexico were detected on February 27, 2020. At that time, the government established a three-phase action plan to reduce the virus's spread among the population. This study aims to determine the association between widespread fear of COVID-19, physiological and affective coping strategies, and post-traumatic stress disorder (PTSD) criteria such as discomfort, negative cognitions, intrusions, and avoidance. These factors are seen as mediating elements associated with collective ineffectiveness in a sample of young people from northern Mexico after the COVID-19 pandemic. A cross-sectional, empirical, descriptive, and correlational study was conducted. Results indicate that most participants exhibited widespread fear of COVID-19, which correlated with avoidance, hyperarousal, intrusive thoughts, and negative cognition and mood symptoms consistent with DSM-5 criteria for PTSD. In the majority of the sample, collective efficacy responses were associated with affective and physiological coping strategies, suggesting these were the primary coping mechanisms employed. Maladaptive behavioral coping strategies were moderately associated with an improvement in collective inefficacy, while negative cognition and mood were linked to a decrease in collective efficacy. Behavioral outcomes were also moderately related to negative affective responses and somatization, characteristic of widespread fear of COVID-19. Objective uncertainties such as risk perception associated with avoidance coping strategies, which hinder social effectiveness, were found, and no planned cognitive coping actions were significant in the sample, a key factor related in the literature to promote healthier states and better community relationships.