Assessment of protection against reinfection with SARS-CoV-2 among 4 million PCR-tested individuals in Denmark in 2020: a population-level observational study / (Record no. 3790)

MARC details
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fixed length control field 03849nam a22002537a 4500
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control field DOH
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control field 20210326125246.0
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Title Assessment of protection against reinfection with SARS-CoV-2 among 4 million PCR-tested individuals in Denmark in 2020: a population-level observational study /
Statement of responsibility, etc. Christian Holm Hansen [and four others]
520 3# - SUMMARY, ETC.
Summary, etc. Background<br/>The degree to which infection with SARS-CoV-2 confers protection towards subsequent reinfection is not well described. In 2020, as part of Denmark's extensive, free-of-charge PCR-testing strategy, approximately 4 million individuals (69% of the population) underwent 10·6 million tests. Using these national PCR-test data from 2020, we estimated protection towards repeat infection with SARS-CoV-2.<br/><br/>Methods<br/>In this population-level observational study, we collected individual-level data on patients who had been tested in Denmark in 2020 from the Danish Microbiology Database and analysed infection rates during the second surge of the COVID-19 epidemic, from Sept 1 to Dec 31, 2020, by comparison of infection rates between individuals with positive and negative PCR tests during the first surge (March to May, 2020). For the main analysis, we excluded people who tested positive for the first time between the two surges and those who died before the second surge. We did an alternative cohort analysis, in which we compared infection rates throughout the year between those with and without a previous confirmed infection at least 3 months earlier, irrespective of date. We also investigated whether differences were found by age group, sex, and time since infection in the alternative cohort analysis. We calculated rate ratios (RRs) adjusted for potential confounders and estimated protection against repeat infection as 1 – RR.<br/><br/>Findings<br/>During the first surge (ie, before June, 2020), 533 381 people were tested, of whom 11 727 (2·20%) were PCR positive, and 525 339 were eligible for follow-up in the second surge, of whom 11 068 (2·11%) had tested positive during the first surge. Among eligible PCR-positive individuals from the first surge of the epidemic, 72 (0·65% [95% CI 0·51–0·82]) tested positive again during the second surge compared with 16 819 (3·27% [3·22–3·32]) of 514 271 who tested negative during the first surge (adjusted RR 0·195 [95% CI 0·155–0·246]). Protection against repeat infection was 80·5% (95% CI 75·4–84·5). The alternative cohort analysis gave similar estimates (adjusted RR 0·212 [0·179–0·251], estimated protection 78·8% [74·9–82·1]). In the alternative cohort analysis, among those aged 65 years and older, observed protection against repeat infection was 47·1% (95% CI 24·7–62·8). We found no difference in estimated protection against repeat infection by sex (male 78·4% [72·1–83·2] vs female 79·1% [73·9–83·3]) or evidence of waning protection over time (3–6 months of follow-up 79·3% [74·4–83·3] vs ≥7 months of follow-up 77·7% [70·9–82·9]).<br/><br/>Interpretation<br/>Our findings could inform decisions on which groups should be vaccinated and advocate for vaccination of previously infected individuals because natural protection, especially among older people, cannot be relied on.
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Linking entry complexity note Lancet 2021 Mar 17; S0140-6736 (21) 00575-4. <br/>doi: 10.1016/S0140-6736(21)00575-4
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Topical term or geographic name entry element SARS-CoV-2
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Topical term or geographic name entry element COVID-19
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Topical term or geographic name entry element Reinfection
General subdivision prevention and control
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Topical term or geographic name entry element Observational Study
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Personal name Hansen, Christian Holm
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Personal name Michlmay, Daniela
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Personal name Gubbels, Sophie Madeleine
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Personal name Mølbak, Kåre
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Personal name Ethelberg, Steen
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Uniform Resource Identifier <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7969130/">https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7969130/</a>
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Koha item type COVID 19 Resource
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-- 3790
-- 3790
Holdings
Withdrawn status Lost status Source of classification or shelving scheme Damaged status Not for loan Home library Current library Shelving location Date acquired Total Checkouts Full call number Barcode Date last seen Price effective from Koha item type
    National Library of Medicine     DOH Central Library DOH Central Library Electronic Resource Section 03/26/2021   C000165 D0001C000165 03/26/2021 03/26/2021 COVID 19 Resource