Estimation of serial intervals and time-varying reproduction numbers across SARS-CoV-2 variants in childcare clusters: symptom onset vs. reporting dates
BMC Infectious Diseases·
- DOI
- 10.1186/s12879-026-14296-1
- PMID
- —
- PMCID
- —
- OpenAlex
- —
- Study type
- Journal article
- Publisher
- Springer Science and Business Media LLC
- Article type
- journal-article
- Integrity
- current
Why this research matters now
The findings suggest that relying on reporting dates in surveillance systems may underestimate real-time transmission intensity and distort epidemic risk assessment in childcare settings, which are high-risk environments for respiratory virus transmission.
Structured evidence summary
Research question
The study investigated whether the choice of temporal reference (symptom onset dates versus reporting dates) affects estimates of serial intervals and time-varying reproduction numbers (Rt) in COVID-19 childcare clusters across different SARS-CoV-2 variant periods.
Study design
This was a retrospective analysis of nationwide surveillance data from the Korea Disease Control and Prevention Agency spanning January 2020 through February 2022, examining four genotype-confirmed childcare clusters (one Before Delta, two Delta, and one Omicron) with at least 50 epidemiologically linked cases each.
Population and setting
The study analyzed COVID-19 outbreak clusters in Korean childcare settings across three SARS-CoV-2 variant periods (Before Delta, Delta, and Omicron), using genotype-confirmed cases from a national surveillance system.
Main findings
Onset-based mean serial interval declined from 9.85 days (Before Delta) to 5.34 days (Omicron), while reporting-based estimates were longer at 8.87 days during Omicron. Reporting-based Rt estimates were consistently lower than onset-based estimates across all variant periods; during Delta, mean Rt was 1.90 using onset dates versus 1.08 using reporting dates.
Public-health relevance
The findings suggest that relying on reporting dates in surveillance systems may underestimate real-time transmission intensity and distort epidemic risk assessment in childcare settings, which are high-risk environments for respiratory virus transmission.
Important limitations
This summary is limited to the supplied single-article abstract/metadata and requires the original paper for decision-grade interpretation. The analysis was based on a small number of clusters (n=4) from a single country, which may limit generalizability.
GIDS interpretation
This study provides methodological evidence about surveillance parameter estimation in childcare outbreak settings. The findings pertain to the accuracy of transmission parameter estimates when using different temporal references and do not directly address any specific 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 8 auditable classifier relationships to diseases, places, topics, and study design.