Publications by authors named "Ragnar F Ingvarsson"

Background: Persistent symptoms are common after SARS-CoV-2 infection but correlation with objective measures is unclear.

Methods: We invited all 3098 adults who tested SARS-CoV-2 positive in Iceland before October 2020 to the deCODE Health Study. We compared multiple symptoms and physical measures between 1706 Icelanders with confirmed prior infection (cases) who participated, and 619 contemporary and 13,779 historical controls.

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Background: The severity of SARS-CoV-2 infection varies from asymptomatic state to severe respiratory failure and the clinical course is difficult to predict. The aim of the study was to develop a prognostic model to predict the severity of COVID-19 in unvaccinated adults at the time of diagnosis.

Methods: All SARS-CoV-2-positive adults in Iceland were prospectively enrolled into a telehealth service at diagnosis.

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Memory T-cell responses following SARS-CoV-2 infection have been extensively investigated but many studies have been small with a limited range of disease severity. Here we analyze SARS-CoV-2 reactive T-cell responses in 768 convalescent SARS-CoV-2-infected (cases) and 500 uninfected (controls) Icelanders. The T-cell responses are stable three to eight months after SARS-CoV-2 infection, irrespective of disease severity and even those with the mildest symptoms induce broad and persistent T-cell responses.

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This cohort study estimates the proportion of persons who became reinfected with SARS-CoV-2 during the Omicron wave in Iceland.

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Objective: To characterise the symptoms of coronavirus disease 2019 (covid-19).

Design: Population based cohort study.

Setting: Iceland.

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Background: Little is known about the nature and durability of the humoral immune response to infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).

Methods: We measured antibodies in serum samples from 30,576 persons in Iceland, using six assays (including two pan-immunoglobulin [pan-Ig] assays), and we determined that the appropriate measure of seropositivity was a positive result with both pan-Ig assays. We tested 2102 samples collected from 1237 persons up to 4 months after diagnosis by a quantitative polymerase-chain-reaction (qPCR) assay.

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Objective: To report the incidence rate ratios (IRR) of acute myocardial infarctions (AMI) and cerebrovascular events (CVE) in incident SLE cases from a defined population. To study the risk factors for cardiovascular events in all patients with SLE at our unit.

Methods: Patients with SLE diagnosed from 1981 to 2006 were followed through to 2016.

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Background: Given the identity between Neisseria meningitidis serogroup B (MenB) capsular polysaccharide (polysialic acid; PSA) and PSA found on neural cell adhesion molecules, it has been proposed that infection with MenB or vaccination with PSA may be associated with subsequent autoimmune or neurological disease.

Methods: We conducted 2 studies. The first was a retrospective nationwide study of invasive meningococcal disease (IMD) in Iceland (with 541 subjects) during the period 1975-2004, and we cross referenced this cohort with databases with respect to subsequent diagnosis of autoimmune disorders.

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Objective: Sexually transmitted diseases and unplanned pregnancies are social and health issues among Icelandic teenagers and are more prevalent than in neighbouring countries. In 2001 knowledge and attitudes to sexual education, sexually transmitted disease and contraception among 16-year olds were investigated by questionnaire. Knowledge was defective.

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Actinomycosis is an infectious disease that has been known since the late nineteenth century. In the pre-antibiotic era it was thought to be rather common but with increased use of antimicrobial agents its incidence has decreased significantly. The causative agent, most commonly Actinomyces israelii, is part of the commensal bacterial flora.

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Aim: To evaluate the influence of maternal smoking during pregnancy on factors influencing fetal growth.

Methods: Thirty newborns of smoking mothers were prospectively compared with 60 newborns of non-smoking mothers. Pre-albumin, albumin, triglycerides, glucose, insulin, insulin-like growth factor I, IGF binding protein 3, pH, lactic acid, erythropoietin and hemoglobin concentrations were measured in umbilical cord blood.

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