Post-acute COVID-19 Sequelae in Denmark

The post-acute phase (PAP) after COVID-19 (four months or more after the acute phase of COVID-19) can manifest with reduced function in multiple organ systems, with a particular focus on the lungs, cardiovascular system, and kidneys. Collectively, these three non-communicable diseases (NCDs) represent a significant burden for both the individual and society as a whole. There is an urgent need to elucidate this connection and build a more detailed understanding of the link between COVID-19's PAP and individual NCDs, as well as to identify robust biomarkers that can assist in the early identification of the development of these NCDs.

This study focuses on PAP and the associated risk factors in this later phase of the disease, examining the relationship between PAP and the increased risk of specifically lung, heart, and kidney complications in the Danish population. Additionally, data (medical records, registry data, patient reported outcomes and blood samples) from a cohort of former patients hospitalized with COVID-19, as well as a control group hospitalized with other respiratory diseases, are investigated to determine the prevalence and risk ratios in disease development more precisely.

The purpose of the study is to contribute to minimizing the risk of developing or worsening NCDs in current and future COVID-19 patients, as well as contributing to our understanding of chronic disease development at the population level. The study aims to investigate the hypothesis that biomarkers can predict if SARS-CoV-2 infection leads to increased and exacerbated non-communicable pulmonary, cardiovascular, and renal diseases.

Further, we address the unmet need to understand the molecular mechanisms responsible for the link between post-acute effects of SARS-CoV-2 and complications in the pulmonary, cardiovascular, and renal system. More specific we will investigate the molecular mechanisms responsible for the aetiology and decline in organ function.

The population in the registry study is the entire population of Denmark. The population in the clinical cohort consists of former patients who have been admitted to Hvidovre Hospital with the diagnosis OBS COVID. Participants consent to the use of residual material from their blood sample, taken during their hospitalization with the diagnosis OBS-COVID in the period 2020-2022 (index blood sample). After obtaining consent, patients come to Hvidovre Hospital, where a blood sample (follow-up blood sample) is taken, and an online questionnaire is completed and stored in REDCap. Blood samples are analyzed and compared with collected registry data and questionnaire data, after which the results are reported in international peer-reviewed journals.

Inclusion criteria

• Has a blood sample in the clinical biobank related to the OBS-COVID index admission
• Aged above 18 years at time of index-admission

Exclusion criteria

• Patients without a Danish personal identification number
• Patients who do not understand or speak Danish