U.S. DHS Provides “Master Question List” Summarizing What’s Known About COVID-19 (Caused by SARS-CoV-2)
Posted: April 22, 2020
The Department of Homeland Security Science and Technology Directorate (DHS S&T) has developed a “Master Question List for COVID-19 (caused by SARS-CoV-2).” This resource is designed to quickly summarize what is known, what additional information is needed, and who may be working to address such fundamental questions as, “What is the infectious dose?” and “How long does the virus persist in the environment?”
As DHS S&T explains, “the Master Question List (MQL) is intended to quickly present the current state of available information to government decision makers in the operational response to COVID-19 and allow structured and scientifically guided discussions across the federal government…to prevent duplication of efforts by highlighting and coordinating research.”
The information contained in the MQL has been assembled and evaluated by experts from publicly available sources, including reports and articles found in scientific and technical journals, selected sources on the internet, and various media reports. All information sources are cited so that individual users may independently evaluate the source content.
According to DHS S&T, the Master Question List is intended to serve as a quick reference tool and should not be regarded as a comprehensive source of information. It is a living document that will be updated as needed when new information becomes available.
We provide excerpts from this document (April 14, 2020 version) below:
Transmissibility – How does it spread from one host to another? How easily is it spread?
SARS-CoV-2 is passed easily between humans, likely through close contact with relatively large droplets and possibly through smaller aerosolized particles.
Individuals can transmit SARS-CoV-2 to others before they have symptoms. Undetected cases play a major role in transmission.
Identifying the contribution of asymptomatic or pre-symptomatic transmission is important for implementing control measures. Additionally, the relative contribution of different infection sources – fomites, droplets, aerosols, and potentially feces – are unknown.
Incubation Period – How long after infection do symptoms appear? Are people infectious during this time?
The majority of individuals develop symptoms within 14 days of exposure. For most people, it takes at least 2 days to develop symptoms, and on average symptoms develop 5 days after exposure. Some individuals never develop symptoms but can still transmit disease.
While the incubation period is well-characterized, less is known about how long individuals are infectious before, during, and after symptoms. Additionally, the possibility of reinfection warrants more research.
Environmental Stability – How long does the agent live in the environment?
SARS-CoV-2 can persist on surfaces for at least 3 days and on the surface of a surgical mask for up to 7 days depending on conditions. If aerosolized intentionally, SARS-CoV-2 is stable for at least several hours. The seasonality of COVID-19 transmission is unknown.
Decontamination – What are effective methods to kill the agent in the environment?
Soap and water, as well as common alcohol and chlorine-based cleaners, hand sanitizers, and disinfectants are effective at inactivating SARS-CoV-2 on hands and surfaces.
Methods for decontaminating N95 masks have been approved by the U.S. Food and Drug Administration (FDA) under Emergency Use Authorization (EUA). Additional decontamination studies, particularly with regard to Personal Protective Equipment (PPE) and other items in short supply, are needed.