Background: The global COVID-19 pandemic has profoundly affected public health. Directly, the pandemic resulted in over 6.6 million deaths, numerous hospitalizations, and widespread illness. The pandemic has also affected health indirectly through government-imposed protective measures, causing decline in mental well-being and increasing social isolation. Unlike previous disasters or crises, the pandemic’s worldwide and enduring impact necessitates a unique research approach. The Network for Health Research in Disasters in the Netherlands responded by initiating a longitudinal, extensive research project called the Integrated Health Monitor COVID-19. The Integrated Health Monitor COVID-19 explores both the direct and indirect health effects of the pandemic at the population level. Methods: The Integrated Health Monitor COVID-19 employs a dual-pronged monitoring strategy alongside an annual literature review. This strategy comprises short-cycle monitoring (conducted quarterly) and long-cycle monitoring (conducted once every one or two years). This comprehensive approach enables the evaluation of health trends during the pandemic, facilitating comparisons with pre-pandemic levels and identification of risk and protective factors. Both monitoring methods incorporate data from surveys and general practice registries. The integration of annual literature reviews with these measurements enables iterative research, while dialogues on policy and practice improvements enhance the knowledge-to-action process. Discussion: Much of the existing knowledge about the potential impact of the COVID-19 pandemic is derived from research on sudden-onset disasters limited to specific geographical areas. This study is anticipated to provide valuable fresh insights into the evolving dynamics of population health and specific vulnerabilities within the ongoing pandemic context.

The COVID-19 pandemic highlighted a critical gap in our knowledge on the impact on mental health, especially trauma-related disorders like PTSD. With future pandemics anticipated due to global health risks, it is essential to rigorously study the prevalence of PTSD resulting from COVID-19. Such research will help us understand the psychological effects of pandemics and develop better strategies for mental health support in future crises. This study uses data from the Dutch Public Health Monitor Adults and Elderly 2022, consisting of 365,000 Dutch adults recruited using random sampling. Pandemic-related and non-COVID related potentially traumatic events were assessed and anchored to a validated screening instrument for PTSD, the Dutch version of the PCL-5. Two-thirds of participants reported experiencing traumatic events during the pandemic. Exposure to pandemic-related traumatic events was reported more frequently than non-COVID related traumatic events. Overall probable PTSD prevalence due to these events was 2.4%, evenly split between pandemic-related and non-COVID related traumatic events. Among exposed individuals, probable PTSD prevalence was 3.7%. The risk was higher for exposure to non-COVID related events such as sexual violence, physical violence and life-threatening accidents than exposure to pandemic-related traumatic events like hospitalization or death of someone significant. Risk factors for developing probable PTSD after exposure to a traumatic event during the pandemic were younger age, financial difficulties, loneliness, low resilience, and experiencing multiple events. Exposure to traumatic events during the pandemic influenced the prevalence of probable PTSD. Despite the lower relative impact of pandemic-related traumatic events compared to non-COVID related traumatic events, exposure to pandemic-related traumatic events accounted for 1.1% of probable PTSD in the population and is thereby comparable in impact to five commonly occurring traumatic events. This emphasizes the need to address mental health consequences and risk factors during pandemics and, potentially, other crises with population-wide exposure to events.

1. In March 2020, the World Health Organization (WHO) declared COVID-19 a global pandemic (WHO, 2020). Since then, the pandemic has resulted in nearly 800 million confirmed cases and over 7 million...

Introduction: The global COVID-19-pandemic influences people's health, both directly through infection and indirectly through the protective measures taken by governments. Previous experience with health research after disasters/crises are generally limited to short-lasting, local disasters with direct consequences for those affected. The COVID-19-pandemic has a different nature: influencing everyone and lasting a longer time. A longitudinal, wide-reaching research-approach is needed to study the health effects of COVID-19. Therefore, the Network GOR-COVID-19, a research group consisting of different organizations, started a monitor on the health effects of COVID-19. Methods: The monitor consists of three main elements: yearly monitoring, quarterly monitoring and literature reviews. Where possible, existing data structures are used. For the quarterly monitoring, two data sources are used: general practitioners’ [GP] registry data and data gathered from panels. The GP data is used for weekly surveillance, giving insight into the prevalence of health symptoms presented to the GP. The panel data is used to gain insight into current self-reported health and wellbeing of people. For the yearly monitoring, two data sources are used. The first is GP data which gives information about the prevalence, incidence and development of symptoms, complaints and diagnoses. It allows for comparison over time and among different population groups. The second is the corona health monitor questionnaire, an existing questionnaire on health and well-being. Finally, literature reviews are conducted annually to create an overview of international and national research about the effects of the COVID-19-pandemic on health. Discussion: Since most of our knowledge about the potential impact of the pandemic stems from research on short-term disasters, limited to specific places, this study is expected to provide valuable new insights.

Introduction: The COVID-19 pandemic introduced widespread stressors and shocking events, impacting mental well-being. Understanding posttraumatic stress disorder (PTSD) prevalence during the pandemic is crucial, yet existing studies on this topic vary widely in methodological quality. This study aims to fill this gap using a large-scale national survey study to examine PTSD prevalence during the pandemic and compare pandemic-related and traditional shocking events. Methods: This study uses data from the Dutch Public Health Monitor Adults and Elderly 2022, consisting of 365,000 Dutch adults representative for the general adult population. Pandemic-related and traditional events were assessed and anchored to a screening instrument for PTSD: the Dutch version of the PCL-5. Results: Two-thirds of participants reported experiencing a shocking event during the pandemic. Exposure to pandemic-related events was reported more frequently than traditional events. Overall probable PTSD prevalence due to these events was 2.4%, evenly split between pandemic-related and traditional events. Among exposed individuals, probable PTSD prevalence was 3.7%. This was higher for traditional than for pandemic-related events. Risk factors for developing probable PTSD after exposure to an event during the pandemic were younger age, financial difficulties, loneliness, low resilience and experiencing multiple events. Discussion: Exposure to shocking events during the pandemic influenced the prevalence of probable PTSD. Despite the lower relative impact of pandemic-related shocking events compared to traditional events, exposure to pandemic-related shocking events accounted for the same amount of probable PTSD cases in the Dutch general population as 5 common traditional events. This emphasizes the need to address mental health consequences of prolonged crises and the demand for healthcare, and the importance of mitigation strategies based on risk and protective factors. Key messages: • Exposure to pandemic-related events accounted for approximately the same amount of probable PTSD cases as 5 frequently occurring traditional events. • Despite pandemic-related events being reported more frequently, traditional events were associated with a relatively higher prevalence of PTSD.

Introduction: There is an ongoing debate about the exposure criterion of PTSD since its introduction in the DSM-III in 1980 and the global COVID-19 pandemic has fueled it. Studies examining the prevalence of PTSD following the COVID-19 pandemic are criticized because assessed stressful pandemic-related events do not fulfill the exposure criterion of the DSM-5 and ICD-11. However, if stressful pandemic-related events are indeed distinct events compared to events that fulfill the exposure criterion, measurement noninvariance of PTSD symptom clusters should occur. The aim of the present study is to test this hypothesis. Methods: For this purpose data from the Dutch Public Health Monitor 2022, based on a large random sample of the Dutch population (n = 72,851) was extracted. We examined the measurement invariance in the PCL-5 subscales across different categories of events that people have experienced during the pandemic, such as the sudden hospitalization of a loved one and not being able to say goodbye to a loved one who passed away due to COVID-19. Results: The mean PCL-5 score was 12.36. PTSD prevalence was 9.74%, higher for events fulfilling the DSM-5 exposure criterion (16.54% vs. 9.05%), with smaller difference between events fulfilling the ICD-11 exposure criterion. Model fit was acceptable across all event categories. Multigroup analyses showed that constraining loadings, intercepts, and error variances did not meaningfully worsen fit, changes in CFI and RMSEA remained below thresholds, supporting measurement invariance across event types. Conclusions: The results show measurement invariance between events during the pandemic that did and that did not comply with the DSM-5 or ICD-11 exposure criterion. These results suggest that the current exposure criteria in the DSM-5 and ICD-11 may not capture all relevant events and underscore the importance of further research to guide potential updates.