First nosocomial cluster of COVID-19 due to the Delta variant in a major acute care hospital in Singapore: investigations and outbreak response.
Open accessAbstract
Objectives The first large nosocomial cluster of coronavirus disease 2019 (COVID-19) in Singapore in April 2021 led to partial closure of a major acute care hospital. This study examined factors associated with infection among patients, staff and visitors; investigated the possible role of aerosol-based transmission; evaluated the effectiveness of BNT162.b2 and mRNA1273 vaccines; and described the successful containment of the cluster.Methods Close contacts of patients with COVID-19 and the affected ward were identified and underwent surveillance for severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection. Patient, staff and visitor cohorts were constructed and factors associated with infection were evaluated. Phylogenetic analysis of patient samples was performed. Ward air exhaust filters were tested for SARS-CoV-2.Results In total, there were 47 cases, comprising 29 patients, nine staff, six visitors and three household contacts. All infections were of the Delta variant. Ventilation studies showed turbulent air flow and swabs from air exhaust filters were positive for SARS-CoV-2. Vaccine breakthrough infections were seen in both patients and staff. Among patients, vaccination was associated with a 79% lower odds of infection with COVID-19 (adjusted odds ratio 0.21, 95% confidence interval 0.05-0.95).Conclusions This cluster occurred despite enhancement of infection control measures that the hospital had undertaken at the onset of the COVID-19 pandemic. It was brought under control rapidly through case isolation, extensive contact tracing and quarantine measures, and led to enhanced use of hospital personal protective equipment, introduction of routine rostered testing of inpatients and staff, and changes in hospital infrastructure to improve ventilation within general wards.
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Cites
MAFFT Multiple Sequence Alignment Software Version 7: Improvements in Performance and Usability
Katoh, K., & Standley, D. M. (2013) · Molecular Biology and Evolution · doi:10.1093/molbev/mst010 · Cited by 46,209 · see citing works
IQ-TREE: A Fast and Effective Stochastic Algorithm for Estimating Maximum-Likelihood Phylogenies
Nguyen, L.-T., Schmidt, H. A., von Haeseler, A., & Minh, B. Q. (2015) · Molecular Biology and Evolution · doi:10.1093/molbev/msu300 · Cited by 26,046 · see citing works
ModelFinder: fast model selection for accurate phylogenetic estimates
Kalyaanamoorthy, S., Minh, B. Q., Wong, T. K. F., von Haeseler, A., & Jermiin, L. S. (2017) · Nature Methods · doi:10.1038/nmeth.4285 · Cited by 18,449 · see citing works
UFBoot2: Improving the Ultrafast Bootstrap Approximation
Hoang, D. T., Chernomor, O., von Haeseler, A., Minh, B. Q., & Vinh, L. S. (2018) · Molecular Biology and Evolution · doi:10.1093/molbev/msx281 · Cited by 10,881 · see citing works
Jalview Version 2—a multiple sequence alignment editor and analysis workbench
Waterhouse, A. M., Procter, J. B., Martin, D. M. A., Clamp, M. E., & Barton, G. J. (2009) · Bioinformatics · doi:10.1093/bioinformatics/btp033 · Cited by 10,011 · see citing works
GISAID: Global initiative on sharing all influenza data – from vision to reality
Shu, Y., & McCauley, J. (2017) · Eurosurveillance · doi:10.2807/1560-7917.es.2017.22.13.30494 · Cited by 3,039 · see citing works
Effectiveness of Covid-19 Vaccines against the B.1.617.2 (Delta) Variant
Lopez Bernal, J., Andrews, N., Gower, C., Gallagher, E., Simmons, R., Thelwall, S., Stowe, J., Tessier, E., Groves, N., Dabrera, G., et al. (2021) · New England Journal of Medicine · doi:10.1056/nejmoa2108891 · Cited by 2,889 · see citing works
Effectiveness of COVID-19 vaccines against the B.1.617.2 variant
Bernal, J. L., Andrews, N., Gower, C., Gallagher, E., Simmons, R., Thelwall, S., Stowe, J., Tessier, E., Groves, N., Dabrera, G., et al. (2021) · doi:10.1101/2021.05.22.21257658 · Cited by 2,888 · see citing works
Ten scientific reasons in support of airborne transmission of SARS-CoV-2
Greenhalgh, T., Jimenez, J. L., Prather, K. A., Tufekci, Z., Fisman, D., & Schooley, R. (2021) · The Lancet · doi:10.1016/s0140-6736(21)00869-2 · Cited by 930 · see citing works
Cherian, S., Potdar, V., Jadhav, S., Yadav, P., Gupta, N., Das, M., Rakshit, P., Singh, S., Abraham, P., Panda, S., et al. (2021) · doi:10.1101/2021.04.22.440932 · Cited by 730 · cited 1× · see citing works
“It is notable that this first COVID-19 nosocomial cluster occurred with the Delta variant, which has been reported to be up to 97% more transmissible than the original strain [20,21].”
Cherian, S., Potdar, V. A., Jadhav, S., Yadav, P. D., Gupta, N., Das, M., Rakshit, P., Singh, S. K., Abraham, P., Panda, S., et al. (2021) · Microorganisms · doi:10.3390/microorganisms9071542 · Cited by 706 · see citing works
Airborne Transmission of SARS-CoV-2
Klompas, M., Baker, M. A., & Rhee, C. (2020) · JAMA · doi:10.1001/jama.2020.12458 · Cited by 394 · see citing works
Tang, J. W., Bahnfleth, W. P., Bluyssen, P. M., Buonanno, G., Jimenez, J. L., Kurnitski, J., Li, Y., Miller, S., Sekhar, C., Morawska, L., et al. (2021) · Journal of Hospital Infection · doi:10.1016/j.jhin.2020.12.022 · Cited by 350 · see citing works
Hoffmann, M., Hofmann-Winkler, H., Krüger, N., Kempf, A., Nehlmeier, I., Graichen, L., Arora, P., Sidarovich, A., Moldenhauer, A.-S., Winkler, M. S., et al. (2021) · Cell Reports · doi:10.1016/j.celrep.2021.109415 · Cited by 258 · see citing works
COVID-19 has redefined airborne transmission
Tang, J. W., Marr, L. C., Li, Y., & Dancer, S. J. (2021) · BMJ · doi:10.1136/bmj.n913 · Cited by 171 · see citing works
A SARS-CoV-2 Cluster in an Acute Care Hospital
Klompas, M., Baker, M. A., Rhee, C., Tucker, R. P., Fiumara, K., Griesbach, D., Bennett-Rizzo, C., Salmasian, H., Wang, R., Wheeler, N. J., et al. (2021) · Annals of Internal Medicine · doi:10.7326/m20-7567 · Cited by 129 · see citing works
Htun, H. L., Lim, D. W., Kyaw, W. M., Loh, W.-N. J., Lee, L. T., Ang, B. S. P., & Chow, A. L. (2020) · Clinical Infectious Diseases · doi:10.1093/cid/ciaa468 · Cited by 67 · see citing works
Self-citationHealthcare workers in Singapore infected with COVID‐19: 23 January‐17 April 2020
Wong, L. Y., Tan, A. L., Leo, Y., Lee, V. J. M., & Toh, M. P. H. S. (2020) · Influenza and Other Respiratory Viruses · doi:10.1111/irv.12803 · Cited by 35 · see citing works
Lee, C. Y., Amrun, S. N., Chee, R. S., Goh, Y. S., Mak, T. M., Octavia, S., Yeo, N. K., Chang, Z. W., Tay, M. Z., Torres‐Ruesta, A., et al. (2021) · Clinical & Translational Immunology · doi:10.1002/cti2.1241 · Cited by 20 · see citing works
Self-citationAsymptomatic health-care worker screening during the COVID-19 pandemic
Chow, A. L., Htun, H. L., Kyaw, W. M., Lee, L. T., & Ang, B. S. P. (2020) · The Lancet · doi:10.1016/s0140-6736(20)32208-x · Cited by 15 · see citing works
Self-citationChow, A. L., Guo, H., Kyaw, W. M., et al. (2021) · Infection Control and Hospital Epidemiology · doi:10.1017/ice.2021.268 · Cited by 11 · see citing works
Self-citationHo, H., Lim, W., Ang, B. S. P., et al. (2020) · Journal of Hospital Infection · doi:10.1016/j.jhin.2020.09.024 · Cited by 9 · see citing works
Self-citation
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Research works printed but not linked: 1
- [7]Garrison E, Marth G. Haplotype-based variant detection from short-read sequencing. arXiv Preprint 2012;arXiv:12073907.
Cited by
Sorted by citations
Ng, O. T., Marimuthu, K., Lim, N., Lim, Z. Q., Thevasagayam, N. M., Koh, V., Chiew, C. J., Ma, S., Koh, M., Low, P. Y., et al. (2022) · JAMA Network Open · doi:10.1001/jamanetworkopen.2022.28900 · Cited by 68 · see citing works
- Authors
- Lim, W.-Y., Tan, G. S. E., Htun, H. L., Phua, H. P., Kyaw, W. M., Guo, H., Cui, L., Mak, T. M., Poh, B. F., Wong, J. C. C., Setoh, Y. X., Ang, B. S. P., & Chow, A. L. P.
- Affiliations
- Nanyang Technological University (SG)
- Tan Tock Seng Hospital (SG)
- National Centre for Infectious Diseases (SG)
- National Environment Agency (SG)
- Corresponding author
- Lim, W-Y.
- ORCID
- Venue
- Journal of Hospital Infection
- Publisher
- Elsevier BV
- Published
- 2022-04
- Volume
- 122
- Pages
- 27-34
- ISSN
- 0195-6701 (ISSN-L)
- PMC
- PMC8687717
- OpenAlex
- W4200130978
- Cited by
- 26
- References
- 23
- Citations by year
- 2026: 1 · 2025: 3 · 2024: 6 · 2023: 6 · 2022: 10
- FWCI
- 3.57
- Type
- journal article
- Language
- en
- Open access
- green
- www.ncbi.nlm.nih.gov
- Locations
- Journal of Hospital Infection (publishedVersion)
- PubMed Central (publishedVersion)
- PubMed (publishedVersion)
- DR-NTU (Nanyang Technological University) (submittedVersion)
- Topics
- Health Sciences › Medicine › Pulmonary and Respiratory Medicine › Infection Control and Ventilation
- Health Sciences › Medicine › Infectious Diseases › SARS-CoV-2 and COVID-19 Research
- Health Sciences › Medicine › Infectious Diseases › Infection Control in Healthcare
- Keywords
- COVID-19 pandemic, Delta variant, hospital outbreak, hospital infection control, airborne transmission, hospital ventilation, breakthrough infection, BNT162b2, mRNA-1273 vaccine, contact tracing, personal protective equipment, phylogenetic analysis
- MeSH terms
- COVID-19, SARS-CoV-2, Cross Infection, Disease Outbreaks, Hospitals, Humans, Phylogeny, Singapore, Pandemics
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