Department of Environmental Health Sciences, University of Michigan School of Public Health, Ann Arbor, MI, USA.
J Expo Sci Environ Epidemiol. 2022 Sep;32(5):751-758. doi: 10.1038/s41370-022-00442-9. Epub 2022 Apr 27.
Evidence is needed on the presence of SARS-CoV-2 in various types of environmental samples and on the estimated transmission risks in non-healthcare settings on campus.
The objective of this research was to collect data on SARS-CoV-2 viral load and to examine potential infection risks of people exposed to the virus in publicly accessible non-healthcare environments on a university campus.
Air and surface samples were collected using wetted wall cyclone bioaerosol samplers and swab kits, respectively, in a longitudinal environmental surveillance program from August 2020 until April 2021 on the University of Michigan Ann Arbor campus. Quantitative rRT-PCR with primers and probes targeting gene N1 were used for SARS-CoV-2 RNA quantification. The RNA concentrations were used to estimate the probability of infection by quantitative microbial risk assessment modeling and Monte-Carlo simulation.
In total, 256 air samples and 517 surface samples were collected during the study period, among which positive rates were 1.6% and 1.4%, respectively. Point-biserial correlation showed that the total case number on campus was significantly higher in weeks with positive environmental samples than in non-positive weeks (p = 0.001). The estimated probability of infection was about 1 per 100 exposures to SARS-CoV-2-laden aerosols through inhalation and as high as 1 per 100,000 exposures from contacting contaminated surfaces in simulated scenarios.
Viral shedding was demonstrated by the detection of viral RNA in multiple air and surface samples on a university campus. The low overall positivity rate indicated that the risk of exposure to SARS-CoV-2 at monitored locations was low. Risk modeling results suggest that inhalation is the predominant route of exposure compared to surface contact, which emphasizes the importance of protecting individuals from airborne transmission of SARS-CoV-2 and potentially other respiratory infectious diseases.
Given the reoccurring epidemics caused by highly infectious respiratory viruses in recent years, our manuscript reinforces the importance of monitoring environmental transmission by the simultaneous sampling and integration of multiple environmental surveillance matrices for modeling and risk assessment.
需要了解 SARS-CoV-2 在各种环境样本中的存在情况，以及在校园非医疗保健环境中估计的传播风险。
本研究旨在收集 SARS-CoV-2 病毒载量的数据，并检查在密歇根大学安娜堡分校校园内公共可进入的非医疗保健环境中接触病毒的人可能存在的感染风险。
在 2020 年 8 月至 2021 年 4 月期间，使用湿壁旋风生物气溶胶采样器和拭子套件分别对空气和表面样本进行了纵向环境监测。使用针对基因 N1 的引物和探针的定量 RT-PCR 对 SARS-CoV-2 RNA 进行定量。使用定量微生物风险评估模型和蒙特卡罗模拟来估算 RNA 浓度估计感染概率。
在研究期间共采集了 256 份空气样本和 517 份表面样本，阳性率分别为 1.6%和 1.4%。点双列相关显示，校园内总病例数在环境样本阳性的周明显高于非阳性的周（p=0.001）。在模拟场景中，通过吸入感染 SARS-CoV-2 气溶胶的暴露量约为每 100 次暴露 1 次，而接触污染表面的暴露量高达每 100000 次暴露 1 次。
在大学校园的多个空气和表面样本中检测到病毒 RNA，证明了病毒的脱落。整体阳性率较低表明在监测地点暴露于 SARS-CoV-2 的风险较低。风险模型结果表明，与表面接触相比，吸入是主要的暴露途径，这强调了保护个人免受 SARS-CoV-2 及潜在其他呼吸道传染病空气传播的重要性。
鉴于近年来高传染性呼吸道病毒反复引发的流行，我们的论文强调了通过同时采样和整合多种环境监测矩阵进行建模和风险评估来监测环境传播的重要性。
