Seroprevalence and infection fatality rate of the SARS-CoV-2 Omicron variant in Denmark : A nationwide serosurveillance study

© 2022 The Authors..

Background: Introduction of the Omicron variant caused a steep rise in SARS-CoV-2 infections despite high vaccination coverage in the Danish population. We used blood donor serosurveillance to estimate the percentage of recently infected residents in the similarly aged background population with no known comorbidity.

Methods: To detect SARS-CoV-2 antibodies induced due to recent infection, and not vaccination, we assessed anti-nucleocapsid (anti-N) immunoglobulin G (IgG) in blood donor samples. Individual level data on SARS-CoV-2 RT-PCR results and vaccination status were available. Anti-N IgG was measured fortnightly from January 18 to April 3, 2022. Samples from November 2021 were analysed to assess seroprevalence before introduction of the Omicron variant in Denmark.

Findings: A total of 43 088 donations from 35 309 Danish blood donors aged 17-72 years were screened. In November 2021, 1·2% (103/8 701) of donors had detectable anti-N IgG antibodies. Adjusting for test sensitivity (estimates ranging from 74%-81%) and November seroprevalence, we estimate that 66% (95% confidence intervals (CI): 63%-70%) of the healthy, similarly aged Danish population had been infected between November 1, 2021, and March 15, 2022. One third of infections were not captured by SARS-CoV-2 RT-PCR testing. The infection fatality rate (IFR) was 6·2 (CI: 5·1-7·5) per 100 000 infections.

Interpretation: Screening for anti-N IgG and linkage to national registers allowed us to detect recent infections and accurately assess assay sensitivity in vaccinated or previously infected individuals during the Omicron outbreak. The IFR was lower than during previous waves.

Funding: The Danish Ministry of Health.

Medienart:

E-Artikel

Erscheinungsjahr:

2022

Erschienen:

2022

Enthalten in:

Zur Gesamtaufnahme - volume:21

Enthalten in:

The Lancet regional health. Europe - 21(2022) vom: 01. Okt., Seite 100479

Sprache:

Englisch

Beteiligte Personen:

Erikstrup, Christian [VerfasserIn]
Laksafoss, Anna Damkjær [VerfasserIn]
Gladov, Josephine [VerfasserIn]
Kaspersen, Kathrine Agergård [VerfasserIn]
Mikkelsen, Susan [VerfasserIn]
Hindhede, Lotte [VerfasserIn]
Boldsen, Jens Kjærgaard [VerfasserIn]
Jørgensen, Signe Winther [VerfasserIn]
Ethelberg, Steen [VerfasserIn]
Holm, Dorte Kinggaard [VerfasserIn]
Bruun, Mie Topholm [VerfasserIn]
Nissen, Janna [VerfasserIn]
Schwinn, Michael [VerfasserIn]
Brodersen, Thorsten [VerfasserIn]
Mikkelsen, Christina [VerfasserIn]
Sækmose, Susanne Gjørup [VerfasserIn]
Sørensen, Erik [VerfasserIn]
Harritshøj, Lene Holm [VerfasserIn]
Aagaard, Bitten [VerfasserIn]
Dinh, Khoa Manh [VerfasserIn]
Busch, Michael P [VerfasserIn]
Jørgensen, Charlotte Sværke [VerfasserIn]
Krause, Tyra Grove [VerfasserIn]
Ullum, Henrik [VerfasserIn]
Ostrowski, Sisse Rye [VerfasserIn]
Espenhain, Laura [VerfasserIn]
Pedersen, Ole Birger Vesterager [VerfasserIn]

Links:

Volltext

Themen:

Infection fatality rate
Journal Article
SARS-CoV-2
Seroprevalence

Anmerkungen:

Date Revised 13.08.2022

published: Print-Electronic

Citation Status PubMed-not-MEDLINE

doi:

10.1016/j.lanepe.2022.100479

funding:

Förderinstitution / Projekttitel:

PPN (Katalog-ID):

NLM344782085