{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,5,27]],"date-time":"2026-05-27T21:30:15Z","timestamp":1779917415278,"version":"3.53.1"},"reference-count":38,"publisher":"BMJ","license":[{"start":{"date-parts":[[2022,4,11]],"date-time":"2022-04-11T00:00:00Z","timestamp":1649635200000},"content-version":"unspecified","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/"}],"content-domain":{"domain":["bmj.com"],"crossmark-restriction":true},"short-container-title":["BMJ"],"accepted":{"date-parts":[[2022,2,23]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:sec>\n                    <jats:title>Objectives<\/jats:title>\n                    <jats:p>To assess the risk of acute and post-acute adverse events after SARS-CoV-2 infection in children and adolescents in Denmark and to evaluate the real world effectiveness of the BNT162b2 mRNA vaccine (Pfizer-BioNTech) among adolescents.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Design<\/jats:title>\n                    <jats:p>Cohort study.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Setting<\/jats:title>\n                    <jats:p>Nationwide Danish healthcare registers.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Participants<\/jats:title>\n                    <jats:p>All Danish people younger than 18 years who were either tested for SARS-CoV-2 using reverse transcriptase polymerase chain reaction (RT-PCR) or vaccinated with BNT162b2 to 1 October 2021.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Main outcome measures<\/jats:title>\n                    <jats:p>Risk of hospital admissions (any hospital contact of \u226512 hours); intensive care unit (ICU) admissions; serious complications, including multisystem inflammatory syndrome in children (MIS-C), myocarditis, and neuroimmune disorders; and initiating drug treatment and health service use up to six months after being tested. Vaccine effectiveness in vaccine recipients compared with unvaccinated peers was evaluated as one minus the risk ratio at 20 days after the first dose and 60 days after the second dose.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>Of 991\u2009682 children and adolescents tested for SARS-CoV-2 using RT-PCR in Denmark, 74\u2009611 (7.5%) were positive. The risk of hospital admission with any variant for \u226512 hours was 0.49% (95% confidence interval 0.44% to 0.54%; 361\/74\u2009350), and 0.01% (0.01% to 0.03%; 10\/73\u2009187) of participants were admitted to an ICU within 30 days of testing positive. The risk of MIS-C within two months of SARS-CoV-2 infection was 0.05% (0.03% to 0.06%; 32\/70\u2009666), whereas no participants had myocarditis outside of MIS-C or encephalitis and fewer than five had Guillain-Barr\u00e9 syndrome. In the post-acute phase (1-6 months after infection), participants who tested positive for SARS-CoV-2 showed a 1.08-fold (95% confidence interval 1.06-fold to 1.10-fold) increase in rate of contacts with general practitioners compared with a reference cohort sampled among all children tested for SARS-CoV-2 during the study period. Overall, 278\u2009649 adolescents received BNT162b2. Compared with unvaccinated adolescents, the estimated vaccine effectiveness among 229\u2009799 adolescents vaccinated with one dose was 62% (95% confidence interval 59% to 65%) after 20 days, and among 175\u2009176 vaccinated with two doses was 93% (92% to 94%) after 60 days during a period when delta was the dominant variant.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusions<\/jats:title>\n                    <jats:p>The absolute risks of adverse events after SARS-CoV-2 infection were generally low in Danish children and adolescents, although MIS-C occurred in 0.05% (32\/70\u2009666) of participants with RT-PCR confirmed SARS-CoV-2 infection. In adjusted analyses, rates of general practitioner visits were slightly increased in SARS-CoV-2 positive children and adolescents, which could indicate persisting symptoms. BNT162b2 appeared to be effective in reducing the risk of SARS-CoV-2 infection with the delta variant in adolescents.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.1136\/bmj-2021-068898","type":"journal-article","created":{"date-parts":[[2022,4,11]],"date-time":"2022-04-11T06:25:13Z","timestamp":1649658313000},"page":"e068898","update-policy":"https:\/\/doi.org\/10.1136\/crossmarkpolicy","source":"Crossref","is-referenced-by-count":32,"title":["Risk of adverse events after covid-19 in Danish children and adolescents and effectiveness of BNT162b2 in adolescents: cohort study"],"prefix":"10.1136","volume":"377","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-1930-5851","authenticated-orcid":false,"given":"Helene","family":"Kildegaard","sequence":"first","affiliation":[{"name":"Clinical Pharmacology, Pharmacy and Environmental Medicine, Department of Public Health, University of Southern Denmark, DK-5000 Odense C, Denmark"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Lars Christian","family":"Lund","sequence":"additional","affiliation":[{"name":"Clinical Pharmacology, Pharmacy and Environmental Medicine, Department of Public Health, University of Southern Denmark, DK-5000 Odense C, Denmark"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Mikkel","family":"H\u00f8jlund","sequence":"additional","affiliation":[{"name":"Clinical Pharmacology, Pharmacy and Environmental Medicine, Department of Public Health, University of Southern Denmark, DK-5000 Odense C, Denmark"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Lone Graff","family":"Stensballe","sequence":"additional","affiliation":[{"name":"Department of Paediatrics and Adolescent Medicine, The Juliane Marie Centre, Rigshospitalet, Denmark"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Anton","family":"Potteg\u00e5rd","sequence":"additional","affiliation":[{"name":"Clinical Pharmacology, Pharmacy and Environmental Medicine, Department of Public Health, University of Southern Denmark, DK-5000 Odense C, Denmark"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"239","published-online":{"date-parts":[[2022,4,11]]},"reference":[{"key":"2025110101482636000_377.apr11_2.e068898.1","unstructured":"Johns Hopkins University of Medicine. 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