*2.3. Measures*

In line with the aim of the original C19PRC-UK study, the measures remained the same in order to allow cross-cultural comparison. Below, the measures that are relevant for the present analysis are described. Items were translated into Italian. The full list is available as Supplementary Material (Supplementary File S1 and https://osf.io/nx2zd/).

*Sociodemographic variables*: we collected the same information as the original C19PRC-UK study [16]: location, presence of adults or minors in the house, income, and previous health issues. We integrated these with further information (region, mourning for COVID-19 human losses, perceived risk to contract COVID-19).

*The Patient Health Questionnaire-15* (PHQ-15) [22] is a 15-item self-report measure based on a 3-point Likert scale. It asks about the presence of somatic symptoms in the last 14 days. In this study, we use both the total scores and the four subscales pain symptoms (0–6), gastrointestinal symptoms (0–8), cardiopulmonary symptoms (0–8), and fatigue symptoms (0–4). As in previous works [16–23] and for the same reasons, item 4 and item 13 were excluded, lowering the maximum score to 26.

*The Patient Health Questionnaire-9* (PHQ-9) [24] was used to measure nine symptoms of depression, asking participants how often they have been bothered by each symptom over the last 14 rated on a four-point Likert scale. The maximum score is 27, which is indicative of a high level of depression. A cut-off score of 10 was used, corresponding to moderate levels of depression [25].

*The Generalized Anxiety Disorder 7-item Scale* (GAD-7) [26] is a seven-item self-report measure based on a four-point Likert scale. It asks participants about anxiety symptoms in the last 14 days. The maximum score is 21, which is indicative of high levels of generalized anxiety. A cut-off of 10 was used, corresponding to a moderately severe level of anxiety [27].

*The International Trauma Questionnaire* (ITQ) [28] is a nine-item self-report measure based on a 5-point Likert scale. Consistently with ICD-11 [29], it asks participants about particular events or behaviors in the last 30 days, across the three symptom clusters of re-experiencing, avoidance, and sense of threat (two items each). Another three items measure functional impairment caused by these symptoms. The maximum score is 24, and a score of ≥2 (*Moderately*) is considered endorsement of that symptom. A PTSD diagnosis requires the endorsement of the three clusters and at least one indicator of functional impairment [30,31].

*COVID-19-related anxiety* was measured through a single item, 'How anxious are you about the coronavirus COVID-19 pandemic?', rated on a continuous scale from 0 to 100. Higher values correspond to higher COVID-19 related anxiety.
