{
  "abstract": "Background: While COVID-19 lockdowns have been systematically associated with increased incidence rate of type 1 diabetes, less is known about the disease rates after lockdowns. We compared the incidence of type 1 diabetes after the COVID-19 pandemic-related closure of society (i) to the time when lockdown was implemented and to (ii) the time before the pandemic in Finland. Methods and findings: The incidence of type 1 diabetes after the lockdown (09/2021–12/2022) was compared to the incidence during the lockdown (03/2020–08/2021) and before the lockdown (three 18-month terms 2014–2019) in Finnish children under the age of 15 years. Previous exposure to SARS-CoV-2 was identified by combining information on COVID-19 vaccination with data on SARS-CoV-2 antibodies analyzed in blood samples. The temporal cohort included 3,467 pediatric type 1 diabetes cases, distributed across post-lockdown (n = 586), lockdown (n = 785), and pre-pandemic (n = 2,096) periods. The incidence of type 1 diabetes after the lockdown was significantly lower than the incidence during the lockdown [incidence rate ratio (IRR = 0.85; 95% Cl [0.77,0.95]; p = 0.004)]. The rate of type 1 diabetes after the lockdown did not significantly differ from the time before lockdown (IRR = 1.00; 95% Cl [0.91,1.09]; p = 0.932). The frequency of children testing positive for infection-associated SARS-CoV-2 antibodies increased from 0.9% during the lockdown to more than 40% after the lockdown. Study limitations include a relatively short follow-up period after the lockdown and the lack of explicit modeling of the underlying long-term secular trend in type 1 diabetes incidence. Conclusions: The lockdown represents a peak in childhood type 1 diabetes incidence in Finland compared to both the pre-pandemic and post-lockdown periods. However, the reversion toward historical levels after the lockdown does not necessarily establish a return to the expected historical trajectory, nor can it fully distinguish a transient change from temporal compensation superimposed on the background secular trend. The contrasting patterns between type 1 diabetes incidence and SARS-CoV-2 antibody prevalence during and after the lockdown suggest an indirect rather than a direct role of the virus in triggering the observed changes in incidence. Why was this study done?: What did the researchers do and find?: What do these findings mean?: In this observational study, Susanna Tall and colleagues found that childhood type 1 diabetes incidence declined in Finland after COVID-19 lockdown restrictions ended, returning to levels comparable with those observed before the pandemic. Their findings suggest that the elevated incidence seen during the lockdown period represented a temporary peak.",
  "abstract_shown": true,
  "affiliations": [
    "Research Program for Clinical and Molecular Metabolism, Faculty of Medicine, University of Helsinki, Helsinki, Finland",
    "Department of Public Health, Finnish Institute for Health and Welfare, Helsinki, Finland",
    "Pediatric Research Center, New Children’s Hospital, Helsinki University Hospital, Helsinki, Finland",
    "Department of Virology, Medicum, University of Helsinki, Helsinki, Finland",
    "Department of Veterinary Biosciences, University of Helsinki, Helsinki, Finland",
    "Biostatistics Consulting, Department of Public Health, Helsinki University Hospital, University of Helsinki, Helsinki, Finland",
    "Erzurum Technical University, Erzurum, Turkey",
    "Virology and Immunology, Helsinki University Hospital Diagnostic Center, Helsinki, Finland",
    "Immunogenetics Laboratory, Institute of Biomedicine, University of Turku, Turku, Finland",
    "Tampere Center for Child, Adolescent and Maternal Health Research, Tampere University and Tampere University Hospital, Tampere, Finland",
    "Tampere University Hospital, Wellbeing Services County of Pirkanmaa, Tampere, Finland",
    "Faculty of Social Sciences, Unit of Health Sciences, Tampere University, Tampere, Finland",
    "Turku, Bioscience Centre, University of Turku and Åbo Akademi University, Turku, Finland"
  ],
  "article_type": "Research Article",
  "arxiv": null,
  "author_total": 16,
  "authors": [
    {
      "affs": [
        0
      ],
      "name": "Susanna Tall"
    },
    {
      "affs": [
        1
      ],
      "name": "Maaret Turtinen"
    },
    {
      "affs": [
        2
      ],
      "name": "Anna Parviainen"
    },
    {
      "affs": [
        3
      ],
      "name": "Jenni Pettersson"
    },
    {
      "affs": [
        4
      ],
      "name": "Anna But"
    },
    {
      "affs": [
        5
      ],
      "name": "Taina Härkönen"
    },
    {
      "affs": [
        6
      ],
      "name": "Jussi Hepojoki"
    },
    {
      "affs": [
        7
      ],
      "name": "Tarja Sironen"
    },
    {
      "affs": [
        8
      ],
      "name": "Rommel Iheozor-Ejiofor"
    },
    {
      "affs": [
        9
      ],
      "name": "Hasan Uğurlu"
    },
    {
      "affs": [
        10
      ],
      "name": "Kalle Saksela"
    },
    {
      "affs": [
        11
      ],
      "name": "Jorma Ilonen"
    },
    {
      "affs": [
        12
      ],
      "name": "Suvi M. Virtanen"
    },
    {
      "name": "Olli Vapalahti"
    },
    {
      "name": "Mikael Knip"
    },
    {
      "name": "on behalf of the Finnish Pediatric Diabetes Register"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/2vrs3hka0q12a.bib",
  "cited_by": 1,
  "doi": "10.1371/journal.pmed.1005288",
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  "licence": "CC-BY-4.0",
  "licence_label": "CC BY 4.0",
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  "published": "2026-11-02",
  "publisher": "Public Library of Science",
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  "title": "Trends in the incidence of childhood type 1 diabetes after the COVID-19 lockdown in Finland: An observational study",
  "title_text": "Trends in the incidence of childhood type 1 diabetes after the COVID-19 lockdown in Finland: An observational study",
  "type": "peer-reviewed",
  "updated_at": "2026-11-04T12:20:44Z",
  "url": "https://research.draconitic.com/paper/2vrs3hka0q12a",
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