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Exploring transmission risk of different routes has major implications for epidemic control. However, disciplinary boundaries have impeded the dissemination of epidemic information, have caused public panic about "air transmission," "air‐conditioning transmission," and "environment‐to‐human transmission," and have triggered "hygiene theater." Animal experiments provide experimental evidence for virus transmission, but more attention is paid to whether transmission is driven by droplets or aerosols and using the dichotomy to describe most transmission events. Here, according to characteristics of experiment setups, combined with patterns of human social interactions, we reviewed and grouped animal transmission experiments into four categories—close contact, short‐range, fomite, and aerosol exposure experiments—and provided enlightenment, with experimental evidence, on the transmission risk of severe acute respiratory syndrome coronavirus (SARS‐COV‐2) in humans via different routes. When referring to "air transmission," context should be showed in elaboration results, rather than whether close contact, short or long range is uniformly described as "air transmission." Close contact and short range are the major routes. When face‐to‐face, unprotected, horizontally directional airflow does promote transmission, due to virus decay and dilution in air, the probability of "air conditioning transmission" is low; the risk of "environment‐to‐human transmission" highly relies on surface contamination and human behavior based on indirect path of "fomite‐hand‐mucosa or conjunctiva" and virus decay on surfaces. Thus, when discussing the transmission risk of SARS‐CoV‐2, we should comprehensively consider the biological basis of virus transmission, environmental conditions, and virus decay. Otherwise, risk of certain transmission routes, such as long‐range and fomite transmission, will be overrated, causing public excessive panic, triggering ineffective actions, and wasting epidemic prevention resources. [ABSTRACT FROM AUTHOR]

Many respiratory infectious diseases are believed to be transmitted from person to person through droplet nuclei in the air or contact with droplet-contaminated surfaces. Most studies related to droplet evaporation only focus on the evaporation process, without dividing the transmission routes of diseases caused by droplet evaporation. In this paper, the actual size of droplet nuclei was analyzed, and droplet evaporation and the changes in component content were predicted. Especially considering the dynamic effect of evaporation on droplets size change, a more realistic sedimentation model was established, and the probability of pathogen transmission through different routes and the corresponding droplet size distribution range were analyzed. The results showed that the size of droplet nuclei and the rate of the evaporation process together determined the time required for droplet evaporation. The number of droplets still suspended in the air after the end of evaporation is much higher than the number of droplets settling on the ground. In addition, the differences in component content during the evaporation process may affect the inactivation of pathogens in droplets. This study provided a reference for the prevention and control strategies of respiratory infectious diseases in indoor environments. [ABSTRACT FROM AUTHOR]

Respiratory infectious diseases are more likely to occur in indoor environments. Therefore, the probability of transmission when sharing the same indoor space with an infected individual for a certain period of time has an impact on the response measures to influenza outbreaks. The experimental methods for studying indoor transmission risks present significant operational challenges. Hence, to accurately predict the process of virus transmission in human living environments, it is crucial to use animal experiments in controlled environments. This study extensively reviews classical documents, taking into account exposure methods as well as environmental factors such as temperature, humidity, viral release intensity, and ventilation frequency. Based on the reference to animal experiments, the analogy law between the animal experiment environment and the human living environment is put forward. For human society, a dynamic respiratory infectious disease model that takes environmental factors into account is developed. The incidence probability of susceptible populations and the law of respiratory virus transmission at a certain time and space are explored. Ultimately, the statistical analysis revealed that temperature and susceptible people, followed by humidity and ventilation frequency, are the most sensitive factors influencing disease outbreak. In conclusion, this research provides a new reference model for predicting the spread of respiratory infectious diseases. It expands the application scope of animal experiments and offers guidance for setting environmental factors in animal virus transmission experiments, assessing the likelihood of infection in human living environments, guiding human behavior, and preparing for future virus outbreaks. [ABSTRACT FROM AUTHOR]