Session 1: Digital activity for same amount of time (e.g. listening to podcast on own smartphone).

5 self-rated items measuring the characteristics of intrusive/unwanted memories in the previous week.

The level of distress, nowness, reliving, disconnectedness and whether different triggers are associated with the intrusive/unwanted memories of the traumatic event(s) are measured on a 101-point scale (from 0 to 100). Higher scores indicate more intrusive/unwanted memories, higher levels of distress/nowness/reliving/disconnectedness and a greater number of different triggers.

Self-report measure that assesses subjective distress after a traumatic event (with reference to study event[s]) in the last week. Here we include the intrusion subscale (8 items) and the avoidance subscale (8 items). Items are rated on a 5-point scale ranging from 0 ("not at all") to 4 ("extremely"). Subscale scores are calculated for the Intrusion or Avoidance items summed (ranging from 0 to 32 each). Higher scores indicate worse outcome.

The PCL-5 short version is an 8-item self-report measure that assesses current symptoms of post-traumatic stress disorder in the last month [Baseline (Day 1), 1, 3, and 6 month follow-up] and in the last week (One week). Items are rated on a 5-point scale ranging from 0 ("not at all") to 4 ("extremely"). The PCL-5 short version yields a total symptom severity score which ranges from 0 to 32. Subscale symptom severity scores for DSM-5 symptom cluster B - intrusion symptoms (items 1-2), cluster C - avoidance (items 3-4), cluster D - negative alterations in cognitions and mood (items 5-6), and cluster E - alterations in arousal and reactivity (items 7-8). Higher scores indicate worse severity.

2 self-rated items measuring the level of distress and vividness associated with the intrusions (11 point scales from 0 to 10) rated within the diary at baseline (Day 1), week 1 and week 5. High scores indicate higher level of distress/vividness.

Eleven items assess the extent of concentration and memory difficulties during the previous four weeks, using a 5-point scale (1 'Virtually every day' to 5 'Never'). Total scores range from 11 to 55; higher scores indicate less concentration and memory difficulties.

3 bespoke items including a question on impact on work-related functioning, and one on daily functioning in other areas associated with the intrusions and a question on perceived social support after the traumatic event. All items are rated on an 11-point scale (from 0 "none"; 5 "some"; 10 "extreme/much"). Higher scores indicate higher level of functional impairment/perceived social support.

6 self-report items (11-point scale from 0 to 100) measuring appraisals of intrusions on two subscales: psychological problems (items 1-3) and negative self-evaluations (items 4-6). Items for each subscale will be summed. Possible subscale scores range from 0 - 300, with higher values indicative of worse appraisals.

Two self rated items: Item 1 measures the extent of being troubled by poor sleep (with reference to study event) on a 5 point scale (from not at all to very much), and item 2 measures the number of nights in the week with sleep problems on a 5 point scale (from 0-1 to 5-7 nights). Each 5-point scale is reverse scored (4 - 0) then summed. Possible total scores range from 0 - 8, with higher values indicative of better sleep.

A single item measuring perceived health status on a seven-point scale (from very good to very bad). The scale is reverse scored. High scores indicate good outcomes.

3 free text response field questions (e.g. which type of health care do you work with right now?) at Day 1 and two free text response field questions on whether the work situation changed and if yes, how, at one week, 1, 3, and 6 month follow-up.

2 bespoke items measuring the total number and the number of full work days on sick leave because of reason for seeking health care. Higher numbers indicate more sick leave.

3 items measuring the frequency of feeling stressed, pressured, tensed at work during the previous week on a 5-point scale (from "never" to "several times per day"). Item scores are summed. Higher scores indicate higher levels of stress. Further, a single item measuring difficulties to let go of work-related thoughts during leisure time (from "very rarely or never" to "very often or always") and a single question about whether the above mentioned difficulties are because of intrusive memories with a yes/no response.

9 self-report items (4-point scale from 1 "not at all" to 4 "all the time") measuring symptoms of burnout on three subscales: Exhaustion (items 1-3), disengagement (items 4-6) and inattentiveness (items 7-9). Subscale scores will be the mean of all items per subscale, the total burnout score will be the mean of all items (ranging from 1-4) with higher scores indicative of higher levels of exhaustion/disengagement/inattentiveness/burnout.

5 self-report items measuring moral stress at work on a 4-point scale ranging from 1 ("Strongly agree") to 4 ("Strongly disagree"). All items are summed. Potential scores range from 5-20, with higher scores indicative of lower levels of moral stress.

A free text response field measuring the occurrence of any health problems since the last contact.

A free text response field asking to imagine a future self identity. Then a free text response field to describe a mental image of this identity, 2 items measuring vividness (from 1 "not vivid at all" to 10 "very vivid") and positivity (from 1 "very negative" to 10 "very positive") of that image on a 10-point scale and 1 item measuring the perspective of viewing that mental image ("through own eyes" or "as if seeing oneself") before and after the traumatic event(s). Higher scores on rating scales indicate higher levels of vividness/positivity.

8 self-report items (5-point scale from 1 to 5) measuring time perspective on three subscales: past perspective (items 3, 5, 7), present perspective (items 1, 8) and future perspective (items 2, 4, 6). Item scores for each subscale will be summed. Higher values indicate higher levels of past/present/future time perspective.

2 free text response field questions (e.g. Are there any specific factors you think have made it easier for you to handle the COVID-19 situation and its consequences?) at Day 1.

12 self-rated items assessing functioning in six life domains: 1) cognition, 2) mobility, 3) personal care 4) relations, 5) daily activities and 6) participation in society. Each item is rated on a 5-point scale, from 1 ("none") to 5 ("extreme or cannot do") and summed; a higher sum score indicates worse functioning. An additional three questions are asked at the end regarding the frequency and impact of these items.

5 item questionnaire (11-point scale from 0 to 10) that rates to what degree the participant finds the intervention credible. High scores indicate greater credibility.

A bespoke manipulation check item measuring self-rated distress during the intervention/control procedure (11-point scale from 0 to 10) at 3 times during the intervention process. Higher scores indicate higher level of distress.

8 bespoke items including questions about study participation e.g. how acceptable was it to do the task? Rated on 11-point scale from 0 (not at all) to 10 (extremely), higher scores indicate higher acceptability; and questions about what has happened since the study with a yes/no response e.g. have you had any psychological or medical treatment since you did the task; and items with a free text response field e.g. do you have any other comments.