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. 2025 Apr;19(4):e70098.
doi: 10.1111/irv.70098.

Excess Respiratory Hospitalisations Associated with Influenza, Respiratory Syncytial Virus and SARS-CoV-2 in Singapore from 2015 to 2023

Chia Hui Qi  1 , Robyn Lim  1 , Rachael Pung  1   2
Affiliations

Excess Respiratory Hospitalisations Associated with Influenza, Respiratory Syncytial Virus and SARS-CoV-2 in Singapore from 2015 to 2023

Chia Hui Qi et al. Influenza Other Respir Viruses. 2025 Apr.

Abstract

Background: The patterns of circulation and burden of influenza and respiratory syncytial virus (RSV) in Singapore are affected by the COVID-19 pandemic containment measures. These patterns in relation to SARS-CoV-2 in a post-pandemic era are unclear.

Methods: Using data from 2015 to 2023, we estimated excess influenza-, RSV- and SARS-CoV-2-associated hospitalisation in Singapore, adjusted for rhinovirus/enterovirus activity in generalised additive models. The data include pneumonia and influenza (P&I) hospitalisation from a national inpatient database and a community-wide acute respiratory infection (ARI) sentinel surveillance programme, stratified by age groups.

Results: Across all age groups, the proportion of hospitalisation associated with influenza, SARS-CoV-2 and RSV was 13.2% (95% CI 5.0%-21.6%), 19.3% (95% CI 13.8%-25.0%) and 4.0% (95% CI 0.9%-12.1%) in 2023, respectively. From 2019 to 2023, all-age influenza-associated hospitalisation declined from 264.4 per 100,000 person-years (95% CI 214.2-313.2) to 203.7 per 100,000 person-years (95% CI 76.8-333.6). In contrast, all-age RSV-associated hospitalisation after the pandemic was 62.2 per 100,000 person-years (95% CI 13.8-186.9), similar to pre-pandemic observations. Peak seasonal influenza occurred 3-8 weeks later as compared with the time of pre-pandemic peak influenza activity.

Conclusion: The overall burden of influenza has declined after the COVID-19 pandemic and its burden is comparable with SARS-CoV-2. Furthermore, shifts in the timing of peak influenza activity suggest a potential need to review the timing of vaccine recommendations in Singapore.

Keywords: RSV; SARS‐CoV‐2; Singapore; hospitalisation; influenza; respiratory.

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Conflict of interest statement

The authors declare no conflicts of interest.

Figures

FIGURE 1
FIGURE 1
Weekly viral and respiratory infection surveillance from 2015–2023. Weekly proportions of respiratory samples from the sentinel ARI surveillance programme tested positive for (A) influenza, (B) RSV, (C) SARS‐CoV‐2 and (D) rhinovirus/enterovirus. Weekly number of hospital admissions by diagnosis codes (E). Horizontal axis labels represent the first e‐week of each year.
See this image and copyright information in PMC

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