Review of animal transmission experiments of respiratory viruses: Implications for transmission risk of SARS-COV-2 in humans via different routes

Ying Li; Ning Mao; Lei Guo; Luyao Guo; Linlin Chen; Li Zhao; Qingqin Wang; Enshen Long

doi:10.1111/risa.14129

Review of animal transmission experiments of respiratory viruses: Implications for transmission risk of SARS-COV-2 in humans via different routes

Risk Anal. 2023 Mar 27. doi: 10.1111/risa.14129. Online ahead of print.

Authors

Ying Li¹, Ning Mao², Lei Guo², Luyao Guo¹, Linlin Chen², Li Zhao³, Qingqin Wang³, Enshen Long^{1

2}

Affiliations

¹ MOE Key Laboratory of Deep Earth Science and Engineering, College of Architecture and Environment, Sichuan University, Chengdu, China.
² MOE Key Laboratory of Deep Earth Science and Engineering, Institute for Disaster Management and Reconstruction, Sichuan University, Chengdu, China.
³ China Academy of Building Research, Beijing, China.

PMID: 36973964
DOI: 10.1111/risa.14129

Abstract

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.

Keywords: SARS-COV-2; animal experimentation; communicable diseases; transmission; virus inactivation.

Grants and funding

52078314/National Natural Science Foundation of China