key: cord-0883857-sg1grxlq authors: Richard, Mathilde; Kok, Adinda; de Meulder, Dennis; Bestebroer, Theo M.; Lamers, Mart M.; Okba, Nisreen M.A.; van Vlissingen, Martje Fentener; Rockx, Barry; Haagmans, Bart L.; Koopmans, Marion P.G.; Fouchier, Ron A.M.; Herfst, Sander title: SARS-CoV-2 is transmitted via contact and via the air between ferrets date: 2020-04-17 journal: bioRxiv DOI: 10.1101/2020.04.16.044503 sha: 880d92ba33ee1bc8704bf2a9cd8a501319699ce0 doc_id: 883857 cord_uid: sg1grxlq SARS-CoV-2, a coronavirus that newly emerged in China in late 2019 1,2 and spread rapidly worldwide, caused the first witnessed pandemic sparked by a coronavirus. As the pandemic progresses, information about the modes of transmission of SARS-CoV-2 among humans is critical to apply appropriate infection control measures and to slow its spread. Here we show that SARS-CoV-2 is transmitted efficiently via direct contact and via the air (via respiratory droplets and/or aerosols) between ferrets. Intranasal inoculation of donor ferrets resulted in a productive upper respiratory tract infection and long-term shedding, up to 11 to 19 days post-inoculation. SARS-CoV-2 transmitted to four out of four direct contact ferrets between 1 and 3 days after exposure and via the air to three out of four independent indirect recipient ferrets between 3 and 7 days after exposure. The pattern of virus shedding in the direct contact and indirect recipient ferrets was similar to that of the inoculated ferrets and infectious virus was isolated from all positive animals, showing that ferrets were productively infected via either route. This study provides experimental evidence of robust transmission of SARS-CoV-2 via the air, supporting the implementation of community-level social distancing measures currently applied in many countries in the world and informing decisions on infection control measures in healthcare settings 3. Current epidemiological data suggest that SARS-CoV-2 is transmitted primarily via respiratory 47 droplets and contact 8-10,14,15 , which is used as the basis for mitigation of spread through physical and 48 social distancing measures. However, scientific evidence that SARS-CoV-2 can be efficiently 49 transmitted via the air is weak. Previous studies have shown that ferrets were susceptible to infection with SARS-CoV 16-20 , and that 51 SARS-CoV was efficiently transmitted to co-housed ferrets via direct contact 16 . Here, we used a 52 ferret transmission model to assess whether SARS-CoV-2 spreads through direct contact and/or 53 through the air (via respiratory droplets and/or aerosols). For this purpose, individually housed donor ferrets were inoculated intranasally with a strain of SARS-CoV-2 isolated from a German 55 traveller returning from China. Six hours post-inoculation (hpi), a direct contact ferret was added to 56 each of the cages. The next day, indirect recipient ferrets were placed in adjacent cages, separated 57 from the donor cages by two steel grids, 10 cm apart, allowing viruses to be transmitted only via the 58 air (Supplementary Figure 1) . On alternating days to prevent cross-contamination, throat, nasal and 59 rectal swabs were collected from each ferret in the inoculated and direct contact groups and from 60 the indirect recipient group, followed by SARS-CoV-2 detection by RT-qPCR and virus titration. Table 1) . In contrast, no infectious virus was isolated from the rectal swabs. Infectious virus titers ranged from 91 10 0,75 to 10 2,75 TCID 50 /ml (median tissue culture infectious dose per ml) in the donor ferrets, from 92 10 0,75 to 10 3,5 TCID 50 /ml in the direct contact ferrets and from 10 0,75 to 10 4,25 TCID 50 /ml in the indirect 93 recipient ferrets. All SARS-CoV-2 positive ferrets seroconverted 21 dpi/dpe, and the antibody levels After the last wash, a 10 μl multi-channel pipet was used to remove residual ethanol. Plates were 280 air-dried for 6 min at room temperature. Plates were removed from the magnetic block and 30 μl of 281 PCR grade water was added to each well and mixed by pipetting up and down 10 times. Plates were 282 incubated for 5 min at room temperature and then placed back on the magnetic block for 2 min to 283 allow separation of the beads. Supernatants were pipetted in a new plate and RNA was kept at 4 o C. The RNA was directly used for RT-qPCR using primers and probes targeting the E gene of SARS-CoV-2 285 as previously described 30 . The primers and probe for PDV detection were described previously 29 . Pattern of early human-to-human transmission of Wuhan Nowcasting and forecasting the potential domestic and 178 international spread of the 2019-nCoV outbreak originating in Wuhan, China: a modelling 179 study Transmission routes of 181 respiratory viruses among humans Community Transmission of Severe Acute Respiratory Syndrome Coronavirus Active Monitoring of Persons Exposed to Patients with Confirmed COVID-186 19 -United States Virology: SARS virus infection of cats and ferrets Human monoclonal antibody as prophylaxis for SARS coronavirus 191 infection in ferrets Immunization with modified vaccinia virus Ankara-based recombinant 193 vaccine against severe acute respiratory syndrome is associated with enhanced hepatitis in 194 ferrets The SARS-CoV ferret model in an infection-challenge study Pathology of experimental SARS coronavirus infection in cats and 198 ferrets Infection and Rapid Transmission of SARS-CoV-2 in Ferrets Simulation of the clinical and pathological manifestations of Coronavirus 202 Disease 2019 (COVID-19) in golden Syrian hamster model: implications for disease 203 pathogenesis and transmissibility Susceptibility of ferrets, cats, dogs, and other domesticated animals to SARS-205 coronavirus 2 Pathogenesis and transmission of swine-origin 2009 A(H1N1) influenza 207 virus in ferrets Prolonged presence of SARS-CoV-2 viral RNA in faecal samples Air, Surface Environmental, and Personal Protective Equipment 211 Contamination by Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) From a 212 Symptomatic Patient Aerosol and Surface Stability of SARS-CoV-2 as Compared with 214 SARS-CoV-1 Escalating infection control response to the rapidly evolving 216 epidemiology of the Coronavirus disease 2019 (COVID-19) due to SARS-CoV-2 in Hong Kong Development and implementation of real-time nucleic acid amplification for the detection of 220 enterovirus infections in comparison to rapid culture of various clinical specimens Detection of 2019 novel coronavirus (2019-nCoV) by real-time RT-PCR All data are available from the corresponding author (S.H.) on reasonable request. No custom software was used in this study. Correspondence and requests for materials should be addressed to Sander Herfst: 324 s.herfst@erasmusmc.nl