Outbreak investigation of airborne transmission of Omicron (B.1.1.529) - SARS-CoV-2 variant of concern in a restaurant: Implication for enhancement of indoor air dilution

Cheng, Vincent Chi-Chung; Wong, Shuk-Ching; Au, Albert Ka-Wing; Wang, Qun; Chen, Hong; Li, Xin; Chu, Allen Wing-Ho; Ip, Jonathan Daniel; Chan, Wan-Mui; Tsoi, Hoi-Wah; Tse, Herman; Ng, Ken Ho-Leung; Kwan, Mike Yat-Wah; Chuang, Shuk-Kwan; To, Kelvin Kai‐Wang; Li, Yuguo; Yuen, Kwok‐Yung

doi:10.1016/j.jhazmat.2022.128504

Cited by 30 publications

(28 citation statements)

References 37 publications

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“…The rst local case of the fth wave was reported on Dec 31, 2021. There was limited local transmission in January 2022 due to several Omicron variant-related clusters which could be traced to imported cases (n=836), including a BA.1 outbreak in a restaurant and a large Omicron BA.2 outbreak in a housing estate which we reported previously 40,41 (Figure 4A). There was also a cluster of pet-storerelated Delta variant AY.127 42 .…”

Section: The Fth Wave Of Covid-19 In Hong Kongmentioning

confidence: 79%

“…We have previously reported our viral genome sequencing results for specimens collected up to February 2, 2022, including those from an Omicron BA.1 restaurant outbreak 41 , an Omicron BA.2 housing estate outbreak 40 , and a Delta AY.127 outbreak related to pet stores 42 . Here, we have performed additional sequencing for specimens collected in Hong Kong up to March 11, 2022 (Supplementary Table S2).…”

Section: Genomic Epidemiology Of the Fth Wave From January To March 2022mentioning

confidence: 99%

“…Results of the surrogate NAb and live virus NAb against the ancestral virus for serum specimens collected between January and April 2021 was reported in our previous publication 30 , but the result of NAb against the Omicron sublineages BA.1 or BA.2 has not been reported before. For viral genome sequencing, 382 sequences were reported in our previous publications 40,41,42 . In the current study, we have performed genome sequencing for 163 randomly selected archived respiratory specimens collected from patients admitted to Queen Mary Hospital.…”

Section: Patientsmentioning

confidence: 99%

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Contribution of low population immunity to the severe Omicron BA.2 outbreak in Hong Kong

Chen

Abdullah

Chan

et al. 2022

Preprint

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Monitoring population protective immunity against SARS-CoV-2 variants is critical for risk assessment. In this serosurveillance study, older adults show much lower seropositive rates of neutralizing antibody (NAb) against ancestral virus than the younger population. The increase in NAb seopositive rate generally follows the population vaccination uptake rate, but older adults have a much lower NAb seropositive rate than vaccination uptake rate. For all age groups, the seropositive rates of NAb against Omicron variant are much lower than those against the ancestral virus. During the fifth wave of COVID-19 in Hong Kong which is dominated by Omicron sublineage BA.2, the case-fatality rate is exceptionally high in the ≥80 year-old age group (9.2%). Our study suggests that the severe BA.2 outbreak in Hong Kong can be attributed by the lack of protective immunity in the population, especially among the vulnerable older adults, and highlights the importance of continual surveillance of protective immunity against emerging variants of SARS-CoV-2.

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Section: The Fth Wave Of Covid-19 In Hong Kongmentioning

confidence: 79%

Section: Genomic Epidemiology Of the Fth Wave From January To March 2022mentioning

confidence: 99%

Section: Patientsmentioning

confidence: 99%

See 1 more Smart Citation

Contribution of low population immunity to the severe Omicron BA.2 outbreak in Hong Kong

Chen

Abdullah

Chan

et al. 2022

Preprint

Self Cite

View full text Add to dashboard Cite

show abstract

“…The first local case of the fifth wave was reported on Dec 31, 2021. There was limited local transmission in January 2022 due to several Omicron variant-related clusters which could be traced to imported cases ( n = 836), including a BA.1 outbreak in a restaurant and a large Omicron BA.2 outbreak in a housing estate which we reported previously 39 , 40 (Fig. 4a ).…”

Section: Resultsmentioning

confidence: 65%

“…We have previously reported our viral genome sequencing results for specimens collected up to February 2, 2022, including those from an Omicron BA.1 restaurant outbreak 40 , an Omicron BA.2 housing estate outbreak 39 , and a Delta AY.127 outbreak related to pet stores 41 . Here, we have performed additional sequencing for specimens collected in Hong Kong up to March 11, 2022 (Supplementary Data 1 ).…”

Section: Resultsmentioning

confidence: 99%

Contribution of low population immunity to the severe Omicron BA.2 outbreak in Hong Kong

et al. 2022

Self Cite

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Monitoring population protective immunity against SARS-CoV-2 variants is critical for risk assessment. We hypothesize that Hong Kong’s explosive Omicron BA.2 outbreak in early 2022 could be explained by low herd immunity. Our seroprevalence study using sera collected from January to December 2021 shows a very low prevalence of neutralizing antibodies (NAb) against ancestral virus among older adults. The age group-specific prevalence of NAb generally correlates with the vaccination uptake rate, but older adults have a much lower NAb seropositive rate than vaccination uptake rate. For all age groups, the seroprevalence of NAb against Omicron variant is much lower than that against the ancestral virus. Our study suggests that this BA.2 outbreak and the exceptionally high case-fatality rate in the ≥80 year-old age group (9.2%) could be attributed to the lack of protective immunity in the population, especially among the vulnerable older adults, and that ongoing sero-surveillance is essential.

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Occupancy-aided ventilation for airborne infection risk control: Continuously or intermittently reduced occupancies?

2022

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Ventilation is an important engineering measure to control the airborne infection risk of acute respiratory diseases, e.g., Corona Virus Disease 2019 (COVID-19). Occupancy-aided ventilation methods can effectively improve the airborne infection risk control performance with a sacrifice of decreasing working productivity because of the reduced occupancy. This study evaluates the effectiveness of two occupancy-aided ventilation methods, i.e., the continuously reduced occupancy method and the intermittently reduced occupancy method. The continuously reduced occupancy method is determined by the steady equation of the mass conservation law of the indoor contaminant, and the intermittently reduced occupancy method is determined by a genetic algorithm-based optimization. A two-scenarios-based evaluation framework is developed, i.e., one with targeted airborne infection risk control performance (indicated by the mean rebreathed fraction) and the other with targeted working productivity (indicated by the accumulated occupancy). The results show that the improvement in the airborne infection risk control performance linearly and quadratically increases with the reduction in the working productivity for the continuously reduced occupancy method and the intermittently reduced occupancy method respectively. At a given targeted airborne infection risk control performance, the intermittently reduced occupancy method outperforms the continuously reduced occupancy method by improving the working productivity by up to 92%. At a given targeted working productivity, the intermittently reduced occupancy method outperforms the continuously reduced occupancy method by improving the airborne infection risk control performance by up to 38%.

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Outbreak investigation of airborne transmission of Omicron (B.1.1.529) - SARS-CoV-2 variant of concern in a restaurant: Implication for enhancement of indoor air dilution

Cited by 30 publications

References 37 publications

Contribution of low population immunity to the severe Omicron BA.2 outbreak in Hong Kong

Contribution of low population immunity to the severe Omicron BA.2 outbreak in Hong Kong

Contribution of low population immunity to the severe Omicron BA.2 outbreak in Hong Kong

Occupancy-aided ventilation for airborne infection risk control: Continuously or intermittently reduced occupancies?

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