Factors affecting stability and infectivity of SARS-CoV-2

Chan, Kwok-Hung; Sridhar, Siddharth; Zhang, Ricky Ruiqi; Chu, Hin; Fung, Agnes Yim-Fong; Chan, Gabriella; Chan, Jasper Fuk-Woo; To, Kelvin Kai-Wang; Hung, Ivan Fan-Ngai; Cheng, Vincent Chi-Chung; Yuen, Kwok-Yung

BACKGROUND: In late 2019, a novel human coronavirus, SARS-CoV-2, emerged in Wuhan, China. This virus has caused a global pandemic involving more than 200 countries. SARS-CoV-2 is highly adapted to humans and readily transmits from person-to-person. AIM: The aim of this study was to investigate the infectivity of SARS-CoV-2 under various environmental factors, disinfectants and different pH conditions. The efficacy of a variety of laboratory virus inactivation methods and home disinfectants against SARS-CoV-2 were investigated. METHODS: The residual virus in dried form or in solution was titrated on Vero E6 cell line at day 0, 1, 3, 5, and 7 after incubation at different temperatures. The viability of virus was determined after treatment with different disinfectants and pH solutions at room temperature (20∼25(o)C). FINDINGS: SARS-CoV-2 was able to retain viability for 3-5 days in dried form or 7 days in solution at room temperature. SARS-CoV-2 could be detected under a wide range of pH conditions from pH4 to pH11 for several days and 1 to 2 days in stool at room temperature but lost 5 logs of infectivity. A variety of commonly used disinfectants and laboratory inactivation procedures were found to reduce viral viability effectively. CONCLUSION: This study demonstrates the stability of SARS-CoV-2 on environmental surfaces and raises the possibility of faecal-oral transmission. Commonly used fixatives, nucleic acid extraction methods and heat inactivation were found to significantly reduce viral infectivity that could ensure hospital and laboratory safety during the COVID-19 pandemic.