Spatio-temporal clustering of respiratory syncytial virus in Sakon Nakhon Province, Thailand, across the COVID-19 pandemic: A retrospective space–time scan analysis, 2019–2024
DOI:
https://doi.org/10.55674/cs.v18i2.265601Keywords:
Respiratory syncytial virus, RSV, spatio-temporal clusters, SaTScanAbstract
Respiratory syncytial virus (RSV) is a leading cause of acute respiratory infections in young children and older adults. The COVID-19 pandemic and the implementation of non-pharmaceutical interventions (NPIs) profoundly altered the transmission dynamics of RSV worldwide. However, evidence describing how RSV spatio-temporal patterns evolved across pandemic-related phases at fine geographic resolution remains limited in Thailand. We conducted a retrospective spatio-temporal cluster analysis of RSV cases reported in Sakon Nakhon Province, northeastern Thailand, between January 2019 and December 2024. Monthly RSV case counts from 125 sub-districts were analyzed using Kulldorff’s space–time scan statistic implemented in SaTScan, applying a space–time permutation model. The analysis was structured into three epidemiological phases: the pre-pandemic (January 2019–March 2020), NPI-associated suppression (April 2020–December 2021), and the post-pandemic resurgence (January 2022–December 2024). Nineteen space–time clusters were identified, eleven of which were statistically significant (p < 0.05). During the pre-pandemic phase, the primary cluster occurred between February 2019 and August 2020, encompassing nine sub-districts and exhibiting more than a sixfold excess of cases (relative risk [RR] = 6.08). Only one moderate-intensity cluster was detected during the suppression phase (RR = 2.71), reflecting markedly reduced RSV activity. Following relaxation of NPIs, RSV transmission rebounded sharply, with a large primary cluster between March and May 2022 involving 15 sub-districts and 1,059 cases (RR = 1.98), followed by multiple significant clusters persisting through 2024. RSV transmission in Sakon Nakhon Province showed marked spatio-temporal shifts across the COVID-19 pandemic, transitioning from localized pre-pandemic clustering to suppressed circulation during NPIs and subsequent widespread resurgence. These findings highlight the influence of pandemic-related interventions on RSV epidemiology and the importance of sub-district–level surveillance for preparedness and response in the post-pandemic era.
GRAPHICAL ABSTRACT
HIGHLIGHTS
- This study provides the first sub-district–level spatio-temporal analysis of RSV transmission in Thailand across the COVID-19 pandemic.
- Space–time scan statistics revealed a clear shift from localized pre-pandemic RSV clusters to widespread post-pandemic resurgence.
- RSV activity was markedly suppressed during COVID-19 non-pharmaceutical interventions, followed by atypical and prolonged outbreaks after restrictions were lifted.
- High-risk locations and outbreak windows were identified that were not apparent from province-wide surveillance alone.
- Fine-scale spatio-temporal methods offer actionable insights to strengthen early warning systems and hospital preparedness for RSV in the post-pandemic era.
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