Field Simulation of Aerosol Transmission of SARS-CoV-2 in a Special Building Layout — Guangdong Province, China, 2021

Zhang, Zhuona; Li, Xia; Wang, Qin; Xu, Jin; Jiang, Qinqin; Jiang, Sili; Lyu, Jiayun; Liu, Shiqiang; Ye, Ling; Yuan, Jun; Feng, Weiyue; Xu, Dongqun

doi:10.46234/ccdcw2021.176

Cited by 16 publications

(9 citation statements)

References 9 publications

(11 reference statements)

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“…The risk of spread of the Delta variant increased through aerosol transmission. Three separate incidents, including five cases associated with playing squash at a sports venue in Maribor, Slovenia (29), a cluster of cases associated with a shopping mall in Wenzhou, China (30), and an outbreak occurred in the rehearsal of Skagit Valley Hymn in West Virginia, USA (31), indicated potential aerosol transmission of the Delta variant. The index case of recent domestic outbreak in Guangzhou was infected in the hospital where the imported case was isolated and tested, which was later determined to be where the aerosol transmission very likely occurred (32).…”

Section: Infectivity and Transmissibilitymentioning

confidence: 99%

Epidemiology Features and Effectiveness of Vaccination and Non-Pharmaceutical Interventions of Delta and Lambda SARS-CoV-2 Variants

Bai¹,

Gu²,

Liu³

et al. 2021

China CDC Weekly

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Section: Infectivity and Transmissibilitymentioning

confidence: 99%

Epidemiology Features and Effectiveness of Vaccination and Non-Pharmaceutical Interventions of Delta and Lambda SARS-CoV-2 Variants

Bai¹,

Gu²,

Liu³

et al. 2021

China CDC Weekly

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“…Previous viral transmissions in high-rise buildings, including the severe acute respiratory syndrome coronavirus 1 (SARS-CoV-1) outbreak in Amoy Garden in Hong Kong [1,2] and SARS-CoV-2 transmission in a high-rise building in Guangzhou [3] and so on, usually took place in vertically distributed rooms on different floors where index cases and infected cases stayed, and the virus was transmitted through vertical sanitary pipelines in the form of aerosol. In addition, viral aerosol can be transmitted from one building to an adjacent building (commonly known as handshake buildings) under a certain airflow layout that was confirmed in a study about SARS-CoV-2 in Guangzhou [4].…”

Section: Introductionmentioning

confidence: 68%

“…Collison Nebulizer (BGI, INC, Waltham, MA, USA) was used to simulate respiration of the infected person and generated 10 12 -10 13 balls per hour. Specific methods were described in previously published papers [4,9,10].…”

Section: Methodsmentioning

confidence: 99%

Simulation Studies Provide Evidence of Aerosol Transmission of SARS-CoV-2 in a Multi-Story Building via Air Supply, Exhaust and Sanitary Pipelines

Zhang¹,

Li²,

Wang³

et al. 2022

IJERPH

Self Cite

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A cross-layer non-vertical transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) occurred in a quarantine hotel in Guangzhou, Guangdong Province, China in June 2021. To explore the cross-layer transmission path and influencing factors of viral aerosol, we set up different scenarios to carry out simulation experiments. The results showed that the air in the polluted room can enter the corridor by opening the door to take food and move out the garbage, then mix with the fresh air taken from the outside as part of the air supply of the central air conditioning system and re-enter into different rooms on the same floor leading to the same-layer transmission. In addition, flushing the toilet after defecation and urination will produce viral aerosol that pollutes rooms on different floors through the exhaust system and the vertical drainage pipe in the bathroom, resulting in cross-layer vertical transmission, also aggravating the transmission in different rooms on the same floor after mixing with the air of the room and entering the corridor to become part of the air supply, and meanwhile, continuing to increase the cross-layer transmission through the vertical drainage pipe. Therefore, the air conditioning and ventilation system of the quarantine hotel should be operated in full fresh air mode and close the return air; the exhaust volume of the bathroom should be greater than the fresh air volume. The exhaust pipe of the bathroom should be independently set and cannot be interconnected or connected in series. The riser of the sewage and drainage pipeline of the bathroom should maintain vertical to exhaust independently and cannot be arbitrarily changed to horizontal pipe assembly.

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“…In the past, it was mainly transmitted through close contact, but now it can be transmitted in the same space. 63 64 The concept of close contact personnel has changed significantly, and its number and scope are much larger than the original definition. This poses a great challenge to the traditional epidemiological investigation.…”

Section: Introductionmentioning

confidence: 99%

“…The incubation period is significantly shortened and the start time of transmission is earlier. In the past, it was mainly transmitted through close contact, but now it can be transmitted in the same space 63 64. The concept of close contact personnel has changed significantly, and its number and scope are much larger than the original definition.…”

Section: Introductionmentioning

confidence: 99%

Urban monitoring, evaluation and application of COVID-19 listed vaccine effectiveness: a health code blockchain study

Wang

Li³

et al. 2022

BMJ Open

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ObjectiveBy using health code blockchain, cities can maximise the use of personal information while maximising the protection of personal privacy in the monitoring and evaluation of the effectiveness of listed vaccines.DesignThis study constructs an urban COVID-19 listed vaccine effectiveness (VE) monitoring, evaluation and application system based on the health code blockchain. This study uses this system and statistical simulation to analyse three urban application scenarios, namely evaluating the vaccination rate (VR) and determining the optimal vaccination strategy, evaluating herd immunity and monitoring the VE on variant.Main outcome measuresThe primary outcomes first establish an urban COVID-19 listed VE monitoring, evaluation and application system by using the health code blockchain, combined with the dynamic monitoring model of VE, the evaluation index system of VE and the monitoring and evaluation system of personal privacy information use, and then three measures are analysed in urban simulation: one is to take the index reflecting urban population mobility as the weight to calculate the comprehensive VR, the second is to calculate the comprehensive basic reproduction number (R) in the presence of asymptomatic persons, the third is to compare the difference between the observed effectiveness and the true effectiveness of listed vaccines under virus variation.ResultsCombining this system and simulation, this study finds: (1) The comprehensive VR, which is weighted to reflect urban population mobility, is more accurate than the simple VR which does not take into account urban population mobility. Based on population mobility, the algorithm principle of urban optimal vaccination strategy is given. In the simulation of urban listed vaccination involving six regions, programmes 1 and 5 have the best protective effect among the eight vaccination programmes, and the optimal vaccination order is 3-5-2-4-6-1. (2) In the presence of asymptomatic conditions, the basic reproduction number, namely R0*(1-VR*VE), does not accurately reflect the effect of herd immunity, but the comprehensive basic reproduction number (R) should be used. The R is directly proportional to the proportion of asymptomatic people (aw) and the duration of the incubation period (ip), and inversely proportional to the VR, the VE and the number of days transmitted in the ip (k). In the simulation analysis, when symptomatic R0=3, even with aw=0.2, the R decreases to nearly 1 until the VR reaches 95%. When aw=0.8, even when the entire population is vaccinated, namely VR=1, the R is 1.688, and still significantly greater than 1. If the R is to be reduced to 1, the VE needs to be increased to 0.87. (3) This system can more comprehensively and accurately grasp the impact of the variant virus on urban VE. The traditional epidemiological investigation can lose the contacts of infected persons, which leads to the deviation between the observed effectiveness and the true effectiveness. Virus variation aggravates the loss, and then increases the deviation. Simulation case 1 assumes the unvaccinated rate of 0.8, the ongoing VR of 0.1, the completed VR of 0.1 and an average infection rate of 2% for the variant virus. If a vaccine is more than 90% effectiveness against the premutant virus, but only 80% effectiveness against the mutant virus, and because 80% of the unvaccinated people who are not infected are not observed, the observed effectiveness of the vaccine is 91.76%, it will lead to the wrong judgement that the VE against the variant virus is not decreased. Simulation case 2 assumes the unvaccinated rate of 0.8, the ongoing VR of 0.1, the completed VR of 0.1 and an average infection rate of 5% for the variant virus. Simulation finds that the higher the proportion of unvaccinated infected people who are not observed, the lower the estimate of observed effectiveness; and the lower the true effectiveness, the larger the gap between observed effectiveness and true effectiveness. Simulation case 3 assumes the unvaccinated rate of 0.2, the ongoing VR of 0.2, the completed VR of 0.6 and an average infection rate of 2% for the variant virus. Simulation finds that the higher the proportion of unobserved completed vaccination patients who are not infected, the lower the estimate of observed effectiveness; and the lower the true effectiveness, the larger the gap between observed effectiveness and true effectiveness. Simulation case 4 assumes the unvaccinated rate of 0.2, the ongoing VR of 0.2, the completed VR of 0.6 and an average infection rate of 5% for the variant virus. If a vaccine is more than 90% effectiveness against the premutant virus, but only 80% effectiveness against the mutant virus, and because 80% of the infected people with complete vaccination are not observed, the observed effectiveness of the vaccine is 91.95%, similar to case 1, it will lead to the wrong judgement that the VE against the variant virus is not decreased.ConclusionCompared with traditional epidemiological investigation, this system can meet the challenges of accelerating virus variation and a large number of asymptomatic people, dynamically monitor and accurately evaluate the effectiveness of listed vaccines and maximise personal privacy without locking down the relevant area or city. This system established in this study could serve as a universal template for monitoring and evaluating the effectiveness of COVID-19 listed vaccines in cities around the world. If this system can be promoted globally, it will promote countries to strengthen unity and cooperation and enhance the global ability to respond to COVID-19.

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Field Simulation of Aerosol Transmission of SARS-CoV-2 in a Special Building Layout — Guangdong Province, China, 2021

Cited by 16 publications

References 9 publications

Epidemiology Features and Effectiveness of Vaccination and Non-Pharmaceutical Interventions of Delta and Lambda SARS-CoV-2 Variants

Epidemiology Features and Effectiveness of Vaccination and Non-Pharmaceutical Interventions of Delta and Lambda SARS-CoV-2 Variants

Simulation Studies Provide Evidence of Aerosol Transmission of SARS-CoV-2 in a Multi-Story Building via Air Supply, Exhaust and Sanitary Pipelines

Urban monitoring, evaluation and application of COVID-19 listed vaccine effectiveness: a health code blockchain study

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