The novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) originated in Wuhan, China in late 2019, and its resulting coronavirus disease, COVID-19, was declared a pandemic by the World Health Organization on March 11, 2020. The rapid global spread of COVID-19 represents perhaps the most significant public health emergency in a century. As the pandemic progressed, a continued paucity of evidence on routes of SARS-CoV-2 transmission has resulted in shifting infection prevention and control guidelines between classically-defined airborne and droplet precautions. During the initial isolation of 13 individuals with COVID-19 at the University of Nebraska Medical Center, we collected air and surface samples to examine viral shedding from isolated individuals. We detected viral contamination among all samples, supporting the use of airborne isolation precautions when caring for COVID-19 patients.

Lack of evidence on SARS-CoV-2 transmission dynamics has led to shifting isolation guidelines between airborne and droplet isolation precautions. During the initial isolation of 13 individuals confirmed positive with COVID-19 infection, air and surface samples were collected in eleven isolation rooms to examine viral shedding from isolated individuals. While all individuals were confirmed positive for SARS-CoV-2, symptoms and viral shedding to the 15 environment varied considerably. Many commonly used items, toilet facilities, and air samples had evidence of viral contamination, indicating that SARS-CoV-2 is shed to the environment as expired particles, during toileting, and through contact with fomites. Disease spread through both direct (droplet and person-to-person) as well as indirect contact (contaminated objects and airborne transmission) are indicated, supporting the use of airborne isolation precautions. 20

A novel highly pathogenic avian influenza (HPAI) H5N8 virus, first detected in January 2014 in poultry and wild birds in South Korea, has spread throughout Asia and Europe and caused outbreaks in Canada and the United States by the end of the year. The spread of H5N8 and the novel reassortant viruses, H5N2 and H5N1 (H5Nx), in domestic poultry across multiple states in the United States pose a potential public health risk. To evaluate the potential of cross-species infection, we determined the pathogenicity and transmissibility of two Asian-origin H5Nx viruses in mammalian animal models. The newly isolated H5N2 and H5N8 viruses were able to cause severe disease in mice only at high doses. Both viruses replicated efficiently in the upper and lower respiratory tracts of ferrets; however, the clinical symptoms were generally mild, and there was no evidence of systemic dissemination of virus to multiple organs. Moreover, these influenza H5Nx viruses lacked the ability to transmit between ferrets in a direct contact setting. We further assessed viral replication kinetics of the novel H5Nx viruses in a human bronchial epithelium cell line, Calu-3. Both H5Nx viruses replicated to a level comparable to a human seasonal H1N1 virus, but significantly lower than a virulent Asian-lineage H5N1 HPAI virus. Although the recently isolated H5N2 and H5N8 viruses displayed moderate pathogenicity in mammalian models, their ability to rapidly spread among avian species, reassort, and generate novel strains underscores the need for continued risk assessment in mammals. O n 16 December 2014, the U.S. Department of Agriculture (USDA) confirmed the presence of a novel highly pathogenic avian influenza (HPAI) H5N8 virus in a captive gyrfalcon and H5N2 virus in a northern pintail duck from Whatcom County, Washington (1). This represented the first appearance of HPAI H5 virus in the United States since 2004 when H5N2 subtype virus was confirmed on a poultry farm in Texas (2). HPAI H5N8 viruses were first reported in duck farms in eastern China in 2010, and in early 2014 a novel reassortant H5N8 virus was detected in poultry in South Korea (3-5). The novel virus, belonging to Eurasian lineage clade 2.3.4.4 (formerly clade 2.3.4.6), subsequently spread to China, Japan, and five countries in Europe (6, 7). In November 2014, the virus was detected on chicken and turkey farms in British Columbia, Canada, followed by Washington State, USA, the following month (8). The novel H5N8 viruses continue to spread to multiple regions and have been found in three North America flyways (Pacific, Central, and Mississippi), where wild-bird migrations occur (USDA, Animal and Plant Health Inspection Service [http://www.aphis.usda.gov]). In addition, genetic reassortment with circulating North American avian influenza viruses has resulted in novel HPAI viruses, including H5N2 and H5N1 subtypes. These novel reassortant viruses carry a Eurasian-origin hemagglutinin (HA) gene genetically related to H5N8 viruses detected in South Korea in 2014 and the neura...