A platform for collaborations in respiratory research in Sweden
Anchor: intro


In December 2019 the novel coronavirus severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) appeared for the first time in Wuhan, China, causing the disease now named coronavirus disease 2019 (COVID-19). Very quickly COVID-19 evolved into a large-scale pandemic that has spread to most countries in the world. To understand and combat the pandemic, there is a continued need for more scientifically sound and detailed information about patients, their risk factors and prognosis, as well as long-term effects after the disease.

The overall aim of SCIFI-PEARL (Swedish Covid-19 Investigation for Future Insights – a Population Epidemiology Approach using Register Linkage) is to conduct broad research on research questions related to COVID-19 and the pandemic. This is accomplished by maintaining a continuously updated overview of how COVID-19 affects the Swedish population. To do this, the project obtains data from a broad range of national and regional healthcare and other registers for the entire Swedish population, and uses those data to conduct analyses across a broad range of topics.

The national personal ID number (personnummer) is used to enable data linkage (i.e. to link data between different healthcare databases). This, together with regular updates of all data (approximately every 3 months), will enable a longitudinal view of the COVID-19 pandemic. The resulting project database is pseudonymized following linkage, by removing personal ID and replacing with a unique study ID. By linking data from national and regional health databases and national quality registers, as well as some other datasources, we investigate Covid-19 patients in the Swedish population to understand patients’ characteristics (e.g. age, morbidity) and how comorbidity (e.g. heart and lung disease and diabetes), medication, or other factors, affect the risk of Covid-19 in terms of more serious illness, worsening disease, dying, or surviving with sequelae. Additionally, SCIFI-PEARL aims to investigate treatment effects of medicines and other interventions, effects and side-effects related to Covid-19 vaccination, as well as effects on healthcare and society during the pandemic.

Anchor: Main sub-projects

Main sub-projects


SCIFI-PEARL: Swedish Covid-19 Investigation for Future Insights – a Population Epidemiology Approach using Register Linkage


In response to the Covid-19 pandemic, we designed and initiated a nationwide multi-register observational study that uses register-based data for timely response to urgent scientific questions related to Covid-19. This overarching project was eventually named the SCIFI-PEARL (Swedish Covid-19 Investigation for Future Insights – a Population Epidemiology Approach using Register Linkage) project.


This project seeks to answer a broad range of current questions with register data, including questions such as:

  • What are the characteristics of Covid-19 patients and how do they differ from a normal population?
  • Which underlying diseases or treatments increase patients’ risk of Covid-19 or unfavourable prognosis?
  • What other factors increase or modify the risk?
  • What aspects of comorbidity, treatments or medical history increase the risk of long-term (1-2 years) consequences of Covid-19 infection, also known as Long Covid / Post Covid-19 condition?
  • Can we develop predictive models that help predict onset or severe prognosis?
  • What are the effects and possible side effects of Covid-19 vaccines in the population?
  • How have the Covid-19 pandemic and vaccination programs affected drug use and healthcare in individuals and society?

Specific research studies / analyses on these topics are individually structured as sub-projects under SCIFI-PEARL.


RECOVAC (Register-based large-scale national population study to monitor Covid-19 vaccination effectiveness and safety)


The RECOVAC (register-based large-scale national population study to monitor COVID-19 vaccination effectiveness and safety) project is a register-based national population study focused on monitoring the effectiveness and safety of COVID-19 vaccinations. It is a major subproject of SCIFI-PEARL, with component subprojects related to vaccination included under it. The RECOVAC project uses a multi-register observational research approach based on the SCIFI-PEARL structure to track the effectiveness of COVID-19 vaccination research and vaccine safety in Sweden.


The RECOVAC subproject may be understood as the vaccine research arm of SCIFI-PEARL. It aims to study Covid-19 vaccination effectiveness and vaccine safety as well as other Covid-19 vaccination program aspects in Sweden. It looks at real life effectiveness of individual vaccines and vaccination programs, adverse reactions to vaccines, vaccination penetration and comparisons between vaccines. RECOVAC also aims to more broadly assess the consequences of the Covid-19 pandemic including vaccination programs on drug utilization, healthcare and other societal aspects (unemployment, income, etc.) in the population.

Anchor: Investigators and study personnel

Investigators and study personnel

Internal project group
Fredrik Nyberg, Project leader and Professor of Register Epidemiology1
Ailiana Santosa, Researcher1
Chioma Nwaru, Postdoc1
Huiqi Li, Researcher and Statistician1
Brian Kirui, PhD Student1
Patricia Ernst, Project Coordinator and Associate Researcher1
Maria Bygdell, Postdoc1
Yiyi Xu, Researcher1

Project Team
Fredrik Nyberg, Project leader and Professor of Register Epidemiology1
Ailiana Santosa, Researcher1
Huiqi Li, Researcher and Statistician1
Johan Sundström, Professor2,3
Lowie Vanfleteren, Senior Lecturer / Specialized Physician4,5
Magnus Gisslen, Professor / Chief Physician3,6
Magnus Lindh, Professor / Chief Physician6,7
Björn Wettermark, Professor at Department of Pharmacy8
Mohammadhossein Hajiebrahimi, Research Assistant8
Niklas Hammar, Project member and Professor emeritus9

1 School of Public Health and Community Medicine, Institute of Medicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
2 Clinical Epidemiology Unit, Department of Medical Sciences, Uppsala University, Uppsala, Sweden
3 The George Institute for Global Health, University of New South Wales, Sydney, Australia
4 COPD Center, Department of Respiratory Medicine and Allergology, Sahlgrenska University Hospital, Gothenburg, Sweden
5 Department of Internal Medicine and Clinical Nutrition, Institute of Medicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
6 Department of Infectious Diseases, Institute of Biomedicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
7 Department of Clinical Microbiology, Sahlgrenska University Hospital, Gothenburg, Sweden
8 Pharmacoepidemiology & Social Pharmacy, Department of Pharmacy, Uppsala University, Uppsala, Sweden
9 Unit of Epidemiology, Institute of Environmental Medicine, Karolinska Institute, Stockholm, Sweden

Anchor: Responsible university or institution

Responsible university or institution

School of Public Health and Community Medicine, Institute of Medicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.

Anchor: Collaborators


The SCIFI-PEARL project and project team members have initiated collaborations with other researchers and groups regarding various topics, and new contacts and collaborations are continuously added. We actively seek and encourage new collaborations. For more information, please see the respective section further down.

Organizations we collaborate with include
University of Gothenburg
Karolinska Institute
Uppsala University
Lund University
Örebro University
Several Swedish regions
Swedish Medical Products Agency (Läkemedelsverket)
Copenhagen University
University of Oslo
SciLifeLab / Swedish COVID-19 Data Portal (https://covid19dataportal.se)

Examples of ongoing collaborations and collaborators
Methodological research (Assoc Prof Carl Bonander, GU), sociodemographics and COVID-19 (Prof Maria Rosvall, GU), statins and COVID-19 (Prof Ingela Parmryd, GU), steroids and COVID-19 (Assoc Prof Daniel Olsson, Assoc Prof Oskar Ragnarsson, Prof Gudmundur Johannsson, GU), vaccination and post COVID-19 condition (Dr Susannah Leach, Dr Maria Bygdell, GU), health economic aspects of COVID-19 (Prof Knut Lönnroth, Dr Jad Shedrawy, KI).

Further collaborations are with representatives of various National Quality Registers: e.g, Assoc Prof Caroline Stridsman, Umeå (Swedish National Airway Register), Assoc Prof Magnus Ekström, Lund, Dr Josefin Sund, Örebro, Prof Ludger Grote, GU (Swedevox), Dr Jonatan Oras, GU (Swedish Intensive Care Register), Prof Soffia Gudbjörnsdottir, GU (National Diabetes Register) and others. We have also initiated discussions about linking the study to well-characterized clinical cohorts, including the West Sweden Asthma Study (WSAS), Prof Hannu Kankaanranta and Dr Bright Nwaru, GU, with whom we also collaborate around machine learning using SCIFI-PEARL register data.

Furthermore, SCIFI-PEARL and its vaccination substudy RECOVAC are part of two VR-funded vaccine research environments across laboratory and register research – one led by Prof Magnus Gisslén, GU, focused on vaccine effectiveness, and one led by Prof Mia Wadelius, Uppsala University, focused on adverse events after vaccination. We also closely collaborate with a Nordic COVID-19 register research study (Nordic COHERENCE, with NordForsk funding), with overlapping research aims, bringing international expertise into our research (Prof Morten Andersen and Assoc Prof Maurizio Sessa, Copenhagen University; Prof Hedvig Nordeng, University of Oslo). Prof Nyberg also has an ongoing collaboration with the OHDSI (Observational Health Data and Informatics) network on COVID-19 research in international databases (Prof Daniel Prieto-Alhambra, Oxford University, and others).

Anchor: Funders


SciLifeLab / Knut and Alice Wallenbergs Foundation
Swedish Research Council
ALF funding
Swedish Heart-Lung Foundation
Social Insurance Agency (Försäkringskassan)

Anchor: How to collaborate with WSAS

How to collaborate with SCIFI-PEARL

Researchers interested in collaborating around scientific analyses using data from the SCIFI-PEARL project database should contact the project for a discussion. We are open to broad collaborations, as we are keen to see the data used as much as possible for purposes of scientific and public interest, within the boundaries of ethics approvals. Current ethics approvals cover a wide range of scientific topics broadly related to healthcare and societal aspects of COVID-19 and/or COVID-19 vaccination, and may be possible to update if required for new topics.

The data in this study are pseudonymized individual-level data from Swedish healthcare registers and have been compiled for the scientific purposes of the RECOVAC and SCIFI-PEARL project, as they are available from the respective Swedish public data holders on the basis of ethics approval for the research in question, subject to relevant legislation, processes and data protection.

We will consider proposals for collaboration in a positive vein, based on an assessment of their interest and importance, fit with the project and realistic possibility of implementation (especially given internal resources within the project). We actively seek and encourage cross-functional collaboration and invite new ideas and expertise. Collaborations will be structured as subprojects under SCIFI-PEARL and the existing PI and leadership, in accordance with existing ethics approvals or subject to obtaining appropriate extended approvals. Arrangements for data access, cost sharing and collaboration support from core project staff and resources will be discussed on a case-by-case basis. Data will not be shared outside of our protected data environments.

Before you contact us, think carefully through the aims for the collaboration with SCIFI-PEARL that you wish to initiate. Please attach a project idea / subproject synopsis or preliminary project plan. You can use your own format. We cannot finance research projects, but are open to collaborate in funding applications.

For more information visit our websites at https://www.gu.se/en/research/scifi-pearl or https://www.gu.se/en/research/recovac.

Anchor: contacts


Fredrik Nyberg
Project leader and Professor of Register Epidemiology
Arvid Wallgrens Backe 2, Building 7
Box 453
405 30 Gothenburg
+46 766-18 62 89

Patricia Ernst
Project coordinator SCIFI-PEARL/RECOVAC
Arvid Wallgrens Backe 2, Building 7
Box 453
405 30 Gothenburg
+46 766-18 62 51

Anchor: publications

Key publications

Nyberg F, Franzén S, Lindh M, Vanfleteren L, Hammar N, Wettermark B, Sundström J, Santosa A, Björck S, Gisslén M. Swedish Covid-19 Investigation for Future Insights – A Population Epidemiology Approach Using Register Linkage (SCIFI-PEARL). Clin Epidemiol. 2021;13:649-659. https://doi.org/10.2147/CLEP.S312742

Nwaru CA, Santosa A, Franzén S, Nyberg F. Occupation and COVID-19 diagnosis, hospitalisation and ICU admission among foreign-born and Swedish-born employees: a register-based study. J Epidemiol Community Health. 2022 Jan 7;76(5):440–7. doi: 10.1136/jech-2021-218278. Epub ahead of print. PMID: 34996808; PMCID: PMC8761595.

Nyberg F, Lindh M, Vanfleteren L, Hammar N, Wettermark B, Sundström J, Santosa A, Kirui BK, Gisslén M. Adverse events of special interest for COVID-19 vaccines – background incidences vary by sex, age and time period and are affected by the pandemic. Preprint. medRxiv 2021.10.04.21263507; doi: https://doi.org/10.1101/2021.10.04.21263507.

Sundh J, Ekström M, Palm A, Ljunggren M, Emilsson ÖI, Grote L, Cajander S, Li H, Nyberg F. COVID-19 and Risk of Oxygen-dependent Chronic Respiratory Failure: A National Cohort Study. Am J Respir Crit Care Med. 2022 May 13. doi: 10.1164/rccm.202202-0323LE. Epub ahead of print. PMID: 35549847.

Spetz M, Lundberg L, Nwaru C, Li H, Santosa A, Leach S, Gisslén M, Hammar N, Rosvall M, Nyberg F. The social patterning of Covid-19 vaccine uptake in older adults: A register-based cross-sectional study in Sweden. Lancet Reg Health Eur. 2022 Apr;15:100331. doi: 10.1016/j.lanepe.2022.100331.

Santosa A, Franzén S, Nåtman J, Wettermark B, Parmryd I, Nyberg F. Protective effects of statins on COVID-19 risk, severity and fatal outcome: a nationwide Swedish cohort study. Sci Rep. 2022 Jul 14;12(1):12047. doi: 10.1038/s41598-022-16357-2. PMID: 35835835; PMCID: PMC9282150.

Mousa SI, Nyberg F, Hajiebrahimi M, Bertilsson R, Nåtman J, Santosa A, Wettermark B. Initiation of antihypertensive drugs to patients with confirmed COVID-19-A population-based cohort study in Sweden. Basic Clin Pharmacol Toxicol. 2022 Sep;131(3):196-204. doi: 10.1111/bcpt.13766. Epub 2022 Jul 6. PMID: 35726121.

Bygdell M, Leach S, Lundberg L, Gyll D, Martikainen J, Santosa A, Li H, Gisslén M, Nyberg F. A comprehensive characterization of patients diagnosed with post-COVID-19 condition in Sweden 16 months after the introduction of the ICD-10 diagnosis code (U09.9): a population-based cohort study. International Journal of Infectious Diseases(2022), doi: https://doi.org/10.1016/j.ijid.2022.11.021.

Dahlén T, Li H, Nyberg F, Edgren G. A population-based, retrospective cohort study of the association between ABO blood group and risk of COVID-19. J Intern Med. 2022 Nov 13. doi: 10.1111/joim.13588. Epub ahead of print. PMID: 36372955

Xu Y, Li H, Kirui B, Santosa A, Gisslen M, Leach S, Wettermark B, Vanfleteren L E.G.W., Nyberg F. Effectiveness of COVID-19 Vaccines Over 13 Months Covering the Period of the Emergence of the Omicron Variant in the Swedish Population. Available at SSRN: https://ssrn.com/abstract=4224504. Preprint.

Anchor: links


WSAS – West Sweden Asthma Study at the University of Gothenburg
Krefting Research Centre