Impact of cross-border-associated cases on the SARS-CoV-2 epidemic in Switzerland during summer 2020 and 2021
Epidemics·
- DOI
- 10.1016/j.epidem.2022.100654
- PMID
- 36444785
- PMCID
- PMC9671612
- OpenAlex
- W4309631075
- Study type
- Journal article
- Publisher
- Elsevier BV
- Article type
- journal-article
- Integrity
- current
Why this research matters now
The findings indicate that cross-border-associated cases were an important component of the modeled Swiss epidemic dynamics during the studied summer periods. The abstract states that understanding this contribution may inform future surveillance strategies.
Structured evidence summary
Research question
The study examined how cases associated with exposure across national borders contributed to SARS-CoV-2 epidemic growth in Switzerland during the summers of 2020 and 2021, compared with local transmission dynamics without imported cases.
Study design
The authors analyzed routine surveillance records of confirmed SARS-CoV-2 cases and used a stochastic branching-process model incorporating superspreading. Simulated epidemic trajectories with and without imported cases were compared for two summer periods.
Population and setting
The setting was Switzerland, using confirmed SARS-CoV-2 cases reported from 1 June through 30 September in 2020 and 2021. Among cases with a known exposure location, the abstract reports that 27% in 2020 and 25% in 2021 reported exposure abroad.
Main findings
The reported case growth during both summer periods was compatible with local effective reproduction estimates above 1 when imported cases were excluded. When imports were included in the model, the estimated local effective reproduction numbers were 0.84 in 2020 and 0.82 in 2021, with both credible intervals below 1. The authors concluded that cross-border-associated cases substantially influenced local transmission dynamics and could account for the observed steady case increase.
Public-health relevance
The findings indicate that cross-border-associated cases were an important component of the modeled Swiss epidemic dynamics during the studied summer periods. The abstract states that understanding this contribution may inform future surveillance strategies.
Important limitations
The evidence is based on routine surveillance data for two defined summer intervals and a stochastic branching-process simulation, so the reported estimates depend on the data and modeling assumptions. Exposure location was not known for all cases. This summary is limited to the supplied single-article abstract and metadata; the original paper is required for decision-grade assessment of methods, assumptions, and uncertainty.
GIDS interpretation
The article is discoverable as a Switzerland-focused SARS-CoV-2 study concerning outbreak investigation, surveillance, transmission dynamics, and travel-associated exposure. Its supplied evidence provides historical study context only and does not establish or confirm any current surveillance signal.
Related GIDS surveillance
Literature context does not validate, explain, or change a surveillance signal. Exact and contextual relationships are shown separately.
Evidence relationships
This article has 11 auditable classifier relationships to diseases, places, topics, and study design.