The Peritraumatic Distress Inventory (PDI) is a well-known self-report questionnaire indexing the distress experienced during and shortly after a most stressful or traumatic event. Although sociodemographic factors contributing to peritraumatic distress have been previously investigated, no research has examined the nature and severity of peritraumatic distress reactions in a non-clinical, community sample as a function of age. An international sample of 5621 adult participants were grouped according the World Health Organization’s age stratification protocol. Mean scores and item endorsement on the PDI were compared across groups with respect to their worst experience of the COVID-19 pandemic. A significant between-group difference was found, F(55,615) = 30.74, p < 0.001, n
2 = 0.027 whereby participants aged 18–39 years old reported the highest levels of peritraumatic distress. This group also endorsed a higher proportion of items on the PDI’s two main factors (emotional distress and physical reactions), and were more likely to endorse feelings of helplessness, than older participants. It appears that severity of peritraumatic distress during the pandemic has affected younger people the most. Results are discussed in light of clinical implications.