Primers used for real-time qPCR.

The SARS-CoV-2 virus caused the COVID-19 pandemic and brought major challenges to public health. It is transmitted via aerosols, droplets, and fomites. Among these, viral transmission through fomites is not well understood although it remains a very important transmission route. This motivated us to study how fomites play a role in viral transmission within controlled indoor environments. To achieve this, we investigated viral aerosol persistence on fomites under different humidity levels to mimic the built environment. We developed a protocol to study the effect of humidity on viral infectivity using a full-scale environmental chamber. The results show that the infectivity of aerosolized Phi6 in air decreased by ≥ 1 log10 as the relative humidity (RH) increased from 25% to 75% but then increased by ≥ 1 log10 as the RH further increased to 85%, resulting in a characteristic V-shape curve which varied with exposure time. Consistently, we show that although material properties may impact viral persistence, changes in the local humidity more significantly influence viral persistence on fomites. These results provide new insights into indoor fomite-mediated viral transmission under different environmental conditions. These findings will help guide the design of more effective strategies for viral control in indoor environments.

新型冠状病毒（SARS-CoV-2）引发了新型冠状病毒肺炎（COVID-19）大流行，对公共卫生事业造成了重大挑战。该病毒可通过气溶胶、飞沫以及媒介物（fomites）进行传播。尽管媒介物传播仍是极为重要的病毒传播途径之一，但目前学界对其介导的病毒传播机制尚未形成充分认知。基于此，本研究旨在探究媒介物在受控室内环境中参与病毒传播的具体作用机制。为达成这一研究目标，本研究模拟实际建成环境，在不同湿度条件下检测了媒介物表面气溶胶态病毒的存留情况。本研究开发了一套完整的实验方案，利用全尺寸环境舱开展湿度对病毒感染性影响的相关研究。研究结果显示，当相对湿度（RH）从25%升高至75%时，空气中气溶胶化的Phi6噬菌体感染性下降了≥1个对数值；而当RH进一步升高至85%时，其感染性则回升了≥1个对数值，由此形成随暴露时长变化的典型V型曲线。本研究同时证实，尽管材料属性会对病毒存留产生一定影响，但局部湿度变化对媒介物表面病毒存留的影响更为显著。上述研究结果为解析不同环境条件下室内媒介物介导的病毒传播机制提供了全新的研究视角。本研究成果可为制定更高效的室内病毒防控策略提供科学指导。