Universal Admission Screening for SARS-CoV-2 Infections among Hospitalized Patients, Switzerland, 2020

I n late 2019, a pneumonia of unknown etiology emerged in Wuhan, Hubei Province, China.In early 2020, public health officials identified the illness as coronavirus disease (COVID-19) and its causative agent as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).The World Health Organization declared a pandemic on March 11, 2020 (1-3), in response to the rapid international spread of COVID-19.The transmission mode of SARS-CoV-2 is not fully understood; it is thought to be spread mostly by respiratory droplets and direct contact (4-6).The median incubation period is ≈5 days (7,8).Among symptomatic patients, men are affected slightly more frequently than women (9,10).COVID-19 has many manifestations, ranging from mild upper airway symptoms to acute respiratory distress syndrome.Common signs and symptoms of COVID-19 include fever, cough, sputum production, and fatigue (11,12).A high proportion of hospitalized CO-VID-19 patients have concurrent conditions such as arterial hypertension, diabetes mellitus, or coronary heart disease (13-17).In March 2020, Rothe et al. published evidence of asymptomatic SARS-CoV-2 transmission (18), and evidence that asymptomatic or presymptomatic persons can transmit SARS-CoV-2 infection has continued to increase (19,20).In many healthcare settings, the number of persons with asymptomatic SARS-CoV-2 infection is unknown.Asymptomatic persons and healthcare workers can contract and spread the infection among hospitalized patients.Many hospitalized patients, who frequently are >65 years of age, have concurrent conditions, or both, are at risk for severe COVID-19.In consideration of these circumstances, hospitals must take precautions to prevent the spread of SARS-CoV-2.For example, some hospitals might screen patients for SARS-CoV-2 infection within 24 hours before an elective intervention (21).Some well-resourced healthcare settings in high incidence areas might benefit from testing patients without COVID-19 symptoms (22).In the canton of Zurich, Switzerland, 4 hospitals introduced universal admission screening of all hospitalized patients in April 2020.We used the results of this screening to assess SARS-CoV-2 prevalence among hospitalized patients and to evaluate the additional yield of a universal screening strategy compared to a symptomdriven approach.