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Open Access 01-12-2022 | SARS-CoV-2 | Research article

Lower transmissibility of SARS-CoV-2 among asymptomatic cases: evidence from contact tracing data in Oslo, Norway

Authors: Fredrik Methi, Elisabeth Henie Madslien

Published in: BMC Medicine | Issue 1/2022

Abstract

Background

Asymptomatic COVID-19 cases have complicated the surveillance and tracking of the pandemic. Previous studies have estimated that 15–25% of all infectees remain asymptomatic.

Methods

Based on contact tracing data from Oslo, Norway, we estimated transmission and susceptibility dynamics among symptomatic and asymptomatic cases and their contacts as identified by manual contact tracing between September 1, 2020, and September 1, 2021.

Results

Among 27,473 indexes and 164,153 registered contacts, the secondary attack rate (SAR-14) was estimated to be 28% lower through asymptomatic exposure (13%) compared to symptomatic exposure (18%). Furthermore, those infected by asymptomatic cases were almost three times more likely to be asymptomatic compared to those infected by symptomatic cases.

Conclusions

Symptomatic cases spread the virus to a greater extent than asymptomatic, and infectees are more likely to be asymptomatic if their assumed infector was asymptomatic.

Available only for authorised users

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Title: Lower transmissibility of SARS-CoV-2 among asymptomatic cases: evidence from contact tracing data in Oslo, Norway
Authors: Fredrik Methi
Elisabeth Henie Madslien
Publication date: 01-12-2022
Publisher: BioMed Central
Keywords: SARS-CoV-2
COVID-19
Published in: BMC Medicine / Issue 1/2022
Electronic ISSN: 1741-7015
DOI: https://doi.org/10.1186/s12916-022-02642-4

At a glance: The ONWARDS insulin icodec trials

Springer Medicine

Lower transmissibility of SARS-CoV-2 among asymptomatic cases: evidence from contact tracing data in Oslo, Norway

Abstract

Background

Methods

Results

Conclusions

At a glance: The ONWARDS insulin icodec trials

Springer Medicine

Abstract

Background

Methods

Results

Conclusions

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