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March 15, 2020 Kelvin Droegemeier, Ph.D. Office of Science and Technology Policy Executive Office of the President Eisenhower Executive Office Building 1650 Pennsylvania Avenue Washington, DC 20504 Dear Dr. Droegemeier: You requested immediate feedback on two crucial questions. The following expert members of the Standing Committee on Emerging Infectious Diseases and 21st Century Health Threats were involved in preparing this document: Kent Kester, David Relman, David Walt, and me. Ellen Clayton, Vanderbilt University, reviewed this document. Question 1: Survival of virus on surfaces. One of the most thorough and informative studies is just now under consideration for publication and has not undergone full peer review. The investigators are a highly reputable group, and we can expect that their study was carefully conducted. They tested both the current coronavirus (SARS-CoV-2) and the original SARS virus (SARS-CoV-1). Results were similar for both viruses. They tested the viability (survival) of virus after controlled aerosolization and on a variety of surfaces. The aerosol (particles smaller than 5 microns that can float in the air) showed viral detection up to 3 hours post aerosolization. Following surface contamination, the virus could be detected up to 4 hours on copper, up to 24 hours on cardboard and up to 2-3 days on plastic and on stainless steel. These results are consistent with the plausibility of both aerosol and surface (fomite) transmission of SARS-CoV-2. The difference in survival on copper (4 hours) and on stainless steel (2-3 days) is noteworthy. Note that this study excludes what is probably the most common route of spread, direct droplet transmission by cough or sneeze, or even exhalation by an infected person. Additionally, the members of the standing committee identified above note that the National Biodefense Analysis and Countermeasures Center (NBACC) is conducting environmental survival studies of the SARS- CoV-2 virus and their results should be taken into account. Question 2: Incubation period (time between exposure and onset of symptoms). Note that it is possible for viral shedding to begin prior to onset of symptoms. Also, we are not considering here the question of how long viral shedding can continue in someone who has been infected. Rather, as we understand it, the question here pertains to the appropriate period of quarantine for an exposed individual. One of the more informative reports on incubation period studied 181 patients in China who had identifiable dates of exposure and of symptom onset (Lauer, et al.). In this study, the mean incubation period was estimated to be 5.1 days (95% confidence interval, 4.5 to 5.8 days) and 97.5 percent of those who develop symptoms will do so within 11.5 days (95% confidence interval 8.2 to 15.6 days) of exposure. These estimates imply that only about 1 percent of cases (101 out of 10,000) will develop symptoms following 14 days after exposure. Shortening quarantine to fewer than 14 days would increase the fraction who were still to develop symptoms. Note that Lauer and colleagues acknowledged that publicly reported cases may overrepresent severe cases, the incubation period for which may differ from that of mild cases. Respectfully, Harvey V. Fineberg, M.D., Ph.D. Chair Standing Committee on Emerging Infectious Diseases and 21st Century Health Threats 500 Fifth Street, NW, Washington, DC 20001