tetano
Editor, Senior Moderator
Build Environ
. 2022 Jun 24;109323.
doi: 10.1016/j.buildenv.2022.109323. Online ahead of print.
Explosive outbreak of SARS-CoV-2 Omicron variant is associated with vertical transmission in high-rise residential buildings in Hong Kong
Vincent Chi-Chung Cheng[SUP] 1 2 [/SUP], Shuk-Ching Wong[SUP] 1 [/SUP], Albert Ka-Wing Au[SUP] 3 [/SUP], Cheng Zhang[SUP] 4 [/SUP], Jonathan Hon-Kwan Chen[SUP] 2 [/SUP], Simon Yung-Chun So[SUP] 2 [/SUP], Xin Li[SUP] 5 [/SUP], Qun Wang[SUP] 4 [/SUP], Kelvin Keru Lu[SUP] 6 [/SUP], David Christopher Lung[SUP] 7 8 [/SUP], Vivien Wai-Man Chuang[SUP] 8 [/SUP], Eric Schuldenfrei[SUP] 9 [/SUP], Gilman Kit-Hang Siu[SUP] 6 [/SUP], Kelvin Kai-Wang To[SUP] 5 [/SUP], Yuguo Li[SUP] 4 [/SUP], Kwok-Yung Yuen[SUP] 5 [/SUP]
Affiliations
Abstract
The phenomenon of vertical transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in high-rise residential buildings (HRRBs) is unique in our densely populated cosmopolitan city. The compulsory testing of a whole building under the scheme of restriction-testing declaration (RTD) during the fourth wave (non-Omicron variant) and fifth wave (mostly Omicron variant) of COVID-19 outbreak in Hong Kong allowed us to study the prevalence of this phenomenon, which may represent a form of airborne transmission. From 23-January-2021 to 24-March-2022, 25,450 (5.8%) of 436,397 residents from 223 (63.0%) of 354 HRRBs under RTD were test-positive for SARS-CoV-2. Using the clustering of cases among vertically aligned flats with shared drainage stack and lightwell as a surrogate marker of vertical transmission, the number of vertically aligned flats with positive COVID-19 cases was significantly higher in the fifth wave compared with the fourth wave (14.2%, 6471/45,531 vs 0.24%, 3/1272; p < 0.001; or 2212 vs 1 per-million-flats; p < 0.001). Excluding 22,801 residents from 38 HRRBs who were tested negative outside the 12-week periods selected in fourth and fifth waves, the positive rate among residents was significantly higher among residents during the fifth wave than the fourth wave (6.5%, 25,434/389,700 vs 0.07%, 16/23,896; p < 0.001). The proportion of HRRBs with COVID-19 cases was significantly higher during the corresponding 12-week period chosen for comparison (78.2%, 219/280 vs 11.1%, 4/36; p < 0.001). Whole-genome phylogenetic analysis of 332 viral genomes showed that Omicron BA.2 was the predominant strain, supporting the high transmissibility of BA.2 by airborne excreta-aerosol route in HRRBs of Hong Kong.
Keywords: BA.2; COVID-19; Residential building; SARS-CoV-2 Omicron variant.
. 2022 Jun 24;109323.
doi: 10.1016/j.buildenv.2022.109323. Online ahead of print.
Explosive outbreak of SARS-CoV-2 Omicron variant is associated with vertical transmission in high-rise residential buildings in Hong Kong
Vincent Chi-Chung Cheng[SUP] 1 2 [/SUP], Shuk-Ching Wong[SUP] 1 [/SUP], Albert Ka-Wing Au[SUP] 3 [/SUP], Cheng Zhang[SUP] 4 [/SUP], Jonathan Hon-Kwan Chen[SUP] 2 [/SUP], Simon Yung-Chun So[SUP] 2 [/SUP], Xin Li[SUP] 5 [/SUP], Qun Wang[SUP] 4 [/SUP], Kelvin Keru Lu[SUP] 6 [/SUP], David Christopher Lung[SUP] 7 8 [/SUP], Vivien Wai-Man Chuang[SUP] 8 [/SUP], Eric Schuldenfrei[SUP] 9 [/SUP], Gilman Kit-Hang Siu[SUP] 6 [/SUP], Kelvin Kai-Wang To[SUP] 5 [/SUP], Yuguo Li[SUP] 4 [/SUP], Kwok-Yung Yuen[SUP] 5 [/SUP]
Affiliations
- PMID: 35765578
- PMCID: PMC9225940
- DOI: 10.1016/j.buildenv.2022.109323
Abstract
The phenomenon of vertical transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in high-rise residential buildings (HRRBs) is unique in our densely populated cosmopolitan city. The compulsory testing of a whole building under the scheme of restriction-testing declaration (RTD) during the fourth wave (non-Omicron variant) and fifth wave (mostly Omicron variant) of COVID-19 outbreak in Hong Kong allowed us to study the prevalence of this phenomenon, which may represent a form of airborne transmission. From 23-January-2021 to 24-March-2022, 25,450 (5.8%) of 436,397 residents from 223 (63.0%) of 354 HRRBs under RTD were test-positive for SARS-CoV-2. Using the clustering of cases among vertically aligned flats with shared drainage stack and lightwell as a surrogate marker of vertical transmission, the number of vertically aligned flats with positive COVID-19 cases was significantly higher in the fifth wave compared with the fourth wave (14.2%, 6471/45,531 vs 0.24%, 3/1272; p < 0.001; or 2212 vs 1 per-million-flats; p < 0.001). Excluding 22,801 residents from 38 HRRBs who were tested negative outside the 12-week periods selected in fourth and fifth waves, the positive rate among residents was significantly higher among residents during the fifth wave than the fourth wave (6.5%, 25,434/389,700 vs 0.07%, 16/23,896; p < 0.001). The proportion of HRRBs with COVID-19 cases was significantly higher during the corresponding 12-week period chosen for comparison (78.2%, 219/280 vs 11.1%, 4/36; p < 0.001). Whole-genome phylogenetic analysis of 332 viral genomes showed that Omicron BA.2 was the predominant strain, supporting the high transmissibility of BA.2 by airborne excreta-aerosol route in HRRBs of Hong Kong.
Keywords: BA.2; COVID-19; Residential building; SARS-CoV-2 Omicron variant.