Scientific article
OA Policy
English

Time trends and modifiable factors of COVID-19 contact tracing coverage, Geneva, Switzerland, June 2020 to February 2022

ContributorsMongin, Denisorcid; Bürgisser, Nils Anthonyorcid; the Covid-SMC Study Group; Courvoisier, Delphineorcid
Published inEurosurveillance, vol. 29, no. 3, 2300228
Publication date2024-01-18
Abstract

Background: Contact tracing was one of the central non-pharmaceutical interventions implemented worldwide to control the spread of SARS-CoV-2, but its effectiveness depends on its ability to detect contacts.

Aim: Evaluate the proportion of secondary infections captured by the contact tracing system in Geneva.

Methods: We analysed 166,892 concomitant infections occurring at the same given address from June 2020 until February 2022 using an extensive operational database of SARS-CoV-2 tests in Geneva. We used permutation to compare the total number of secondary infections occurring at the same address with that reported through manual contact tracing.

Results: Contact tracing captured on average 41% of secondary infections, varying from 23% during epidemic peaks to 60% during low epidemic activity. People living in wealthy neighbourhoods were less likely to report contacts (odds ratio (OR): 1.6). People living in apartment buildings were also less likely to report contacts than those living in a house (OR: 1.1–3.1) depending on the SARS-CoV-2 variant, the building size and the presence of shops. This under-reporting of contacts in apartment buildings decreased during periods of mandatory wearing of face masks and restrictions on private gatherings.

Conclusion: Contact tracing alone did not detect sufficient secondary infections to reduce the spread of SARS-CoV-2. Campaigns targeting specific populations, such as those in wealthy areas or apartment buildings, could enhance coverage. Additionally, measures like wearing face masks, improving ventilation and implementing restrictions on gatherings should also be considered to reduce infections resulting from interactions that may not be perceived as high risk.

Keywords
  • COVID-19
  • Contact tracing
  • Non-pharmaceutical interventions
  • COVID-19 / epidemiology
  • COVID-19 / prevention & control
  • Coinfection
  • Contact Tracing / methods
  • Humans
  • SARS-CoV-2
  • Switzerland / epidemiology
NoteThis work was published as a preprint article on MedRxiv (Mongin D, Bürgisser N, Courvoisier DS, the Covid-SMC Study Group. Coverage of state-initiated contact-trac- ing during COVID-19 and factors influencing it: evidence from real-world data. MedRxiv. 2023 Mar 22). https://doi. org/10.1101/2023.03.22.23287577
Citation (ISO format)
MONGIN, Denis, BÜRGISSER, Nils Anthony, COURVOISIER, Delphine. Time trends and modifiable factors of COVID-19 contact tracing coverage, Geneva, Switzerland, June 2020 to February 2022. In: Eurosurveillance, 2024, vol. 29, n° 3, p. 2300228. doi: 10.2807/1560-7917.ES.2024.29.3.2300228
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Identifiers
Journal ISSN1025-496X
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Creation07/08/2024 11:50:47 AM
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Update time02/03/2025 1:43:43 PM
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