TY - JOUR
T1 - Nosocomial Outbreak of Coronavirus Disease 2019 by Possible Airborne Transmission Leading to a Superspreading Event
AU - Cheng, Vincent Chi Chung
AU - Fung, Kitty Sau Chun
AU - Siu, Gilman Kit Hang
AU - Wong, Shuk Ching
AU - Cheng, Lily Shui Kuen
AU - Wong, Man Sing
AU - Lee, Lam Kwong
AU - Chan, Wan Mui
AU - Chau, Ka Yee
AU - Leung, Jake Siu Lun
AU - Chu, Allen Wing Ho
AU - Chan, Wai Shan
AU - Lu, Kelvin Keru
AU - Tam, Kingsley King Gee
AU - Ip, Jonathan Daniel
AU - Leung, Kenneth Siu Sing
AU - Lung, David Christopher
AU - Tse, Herman
AU - To, Kelvin Kai Wang
AU - Yuen, Kwok Yung
N1 - Publisher Copyright:
© The Author(s) 2021.
PY - 2021/9/15
Y1 - 2021/9/15
N2 - Background. Nosocomial outbreaks with superspreading of coronavirus disease 2019 due to a possible airborne transmission have not been reported. Methods. Epidemiological analysis, environmental samplings, and whole-genome sequencing (WGS) were performed for a hospital outbreak. Results. A superspreading event that involved 12 patients and 9 healthcare workers (HCWs) occurred within 9 days in 3 of 6 cubicles at an old-fashioned general ward with no air exhaust built within the cubicles. The environmental contamination by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA was significantly higher in air grilles (>2 m from patients' heads and not within reach) than on high-touch clinical surfaces (36.4%, 8 of 22 vs 3.4%, 1 of 29, P = .003). Six (66.7%) of 9 contaminated air exhaust grilles were located outside patient cubicles. The clinical attack rate of patients was significantly higher than of HCWs (15.4%, 12 of 78 exposed patients vs 4.6%, 9 of 195 exposed HCWs, P = .005). Moreover, the clinical attack rate of ward-based HCWs was significantly higher than of nonward-based HCWs (8.1%, 7 of 68 vs 1.8%, 2 of 109, P = .045). The episodes (mean ± standard deviation) of patient-care duty assignment in the cubicles was significantly higher among infected ward-based HCWs than among noninfected ward-based HCWs (6.0 ± 2.4 vs 3.0 ± 2.9, P = .012) during the outbreak period. The outbreak strains belong to SARSCoV-2 lineage B.1.36.27 (GISAID clade GH) with the unique S-T470N mutation on WGS. Conclusions. This nosocomial point source superspreading event due to possible airborne transmission demonstrates the need for stringent SARS-CoV-2 screening at admission to healthcare facilities and better architectural design of ventilation systems to prevent such outbreaks. Portable high-efficiency particulate filters were installed in each cubicle to improve ventilation before resumption of clinical service.
AB - Background. Nosocomial outbreaks with superspreading of coronavirus disease 2019 due to a possible airborne transmission have not been reported. Methods. Epidemiological analysis, environmental samplings, and whole-genome sequencing (WGS) were performed for a hospital outbreak. Results. A superspreading event that involved 12 patients and 9 healthcare workers (HCWs) occurred within 9 days in 3 of 6 cubicles at an old-fashioned general ward with no air exhaust built within the cubicles. The environmental contamination by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA was significantly higher in air grilles (>2 m from patients' heads and not within reach) than on high-touch clinical surfaces (36.4%, 8 of 22 vs 3.4%, 1 of 29, P = .003). Six (66.7%) of 9 contaminated air exhaust grilles were located outside patient cubicles. The clinical attack rate of patients was significantly higher than of HCWs (15.4%, 12 of 78 exposed patients vs 4.6%, 9 of 195 exposed HCWs, P = .005). Moreover, the clinical attack rate of ward-based HCWs was significantly higher than of nonward-based HCWs (8.1%, 7 of 68 vs 1.8%, 2 of 109, P = .045). The episodes (mean ± standard deviation) of patient-care duty assignment in the cubicles was significantly higher among infected ward-based HCWs than among noninfected ward-based HCWs (6.0 ± 2.4 vs 3.0 ± 2.9, P = .012) during the outbreak period. The outbreak strains belong to SARSCoV-2 lineage B.1.36.27 (GISAID clade GH) with the unique S-T470N mutation on WGS. Conclusions. This nosocomial point source superspreading event due to possible airborne transmission demonstrates the need for stringent SARS-CoV-2 screening at admission to healthcare facilities and better architectural design of ventilation systems to prevent such outbreaks. Portable high-efficiency particulate filters were installed in each cubicle to improve ventilation before resumption of clinical service.
KW - COVID-19
KW - airborne transmission
KW - hospital outbreak
KW - ventilation system
KW - whole genome sequencing
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U2 - 10.1093/cid/ciab313
DO - 10.1093/cid/ciab313
M3 - Article
C2 - 33851214
AN - SCOPUS:85116958765
SN - 1058-4838
VL - 73
SP - E1356-E1364
JO - Clinical Infectious Diseases
JF - Clinical Infectious Diseases
IS - 6
ER -