Asymptomatic health-care worker screening during the COVID-19 pandemic
Authors: Kevin Fennelly, Christopher C Whalen
Journal: The Lancet (2020)

We applaud the establishment of the COVIDsortium by Thomas Treibel and colleagues1Treibel TA Manisty C Burton M et al.COVID-19: PCR screening of asymptomatic health-care workers at London hospital.Lancet. 2020; 395: 1608-1610Summary Full Text Full Text PDF PubMed Scopus (221) Google Scholar as a bioresource focusing on asymptomatic health-care workers (HCWs).1Treibel TA Manisty C Burton M et al.COVID-19: PCR screening of asymptomatic health-care workers at London hospital.Lancet. 2020; 395: 1608-1610Summary Full Text Full Text PDF PubMed Scopus (221) Google Scholar However, we disagree with the authors' conclusion that "the rate of asymptomatic infection among HCWs more likely reflects general community transmission than in-hospital exposure". This report was an ecological study subject to the ecological fallacy. Moreover, the figure compares symptomatic inpatients who were tested in hospital with asymptomatic HCWs. It is possible that HCWs were exposed to asymptomatic patients who were infectious in the hospital or to patients with false-negative tests. The number of infections among HCWs was also most likely underestimated, as HCWs with symptoms or who were self-isolating were excluded. The role of hospital exposures versus community exposures has been problematic for assessments of the occupational risk of other infectious diseases (eg, multidrug-resistant tuberculosis). Valid risks for disease were not appreciated until HCWs were compared with controls with similar educational and economic status, such as medical students versus chemical-engineering students.2Silva VMC Cunha AJLA Oliveira JR et al.Medical students at risk of nosocomial transmission of Mycobacterium tuberculosis.Int J Tuberc Lung Dis. 2000; 4: 420-426PubMed Google Scholar Finally, evidence exists that the risk to HCWs from severe acute respiratory syndrome coronavirus 2 is not only from community exposures but also from other types of exposures. Among 1423 HCWs in the USA with COVID-19, 780 (55%) HCWs reported contact with a patient with confirmed COVID-19 in the 14 days before the onset of their symptoms, whereas 384 (27%) reported contact only with a household member, 187 (13%) in a community setting, and 72 (5%) in more than one of these settings.3Burrer SL De Perio MA Hughes MM et al.Characteristics of health care personnel with COVID-19—United States, February 12–April 9, 2020.MMWR Morb Mortal Wkly Rep. 2020; 69: 477-481Crossref PubMed Scopus (569) Google Scholar Some HCW exposures confer a higher risk than do others, and personal protective equipment and infection control training are associated with a decreased risk of infection.4Chou R Dana T Buckley DI Selph S Fu R Totten AM Epidemiology of and risk factors for coronavirus infection in health care workers: a living rapid review.Ann Intern Med. 2020; 173: 120-136Crossref PubMed Scopus (425) Google Scholar We declare no competing interests. COVID-19: PCR screening of asymptomatic health-care workers at London hospitalThe exponential growth in coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) across the UK has been successfully reversed by social distancing and lockdown.1 RNA testing for prevalent infection is a key part of the exit strategy, but the role of testing for asymptomatic infection remains unclear.2 Understanding the determinants of asymptomatic or pauci-symptomatic infection will provide new opportunities for personalised risk stratification and reveal much-needed correlates of protective immunity, whether induced by vaccination or natural exposure. Full-Text PDF Asymptomatic health-care worker screening during the COVID-19 pandemicMass testing of asymptomatic health-care workers (HCWs) has been suggested to reduce nosocomial transmission of COVID-19.1 This level of testing might not be necessary in hospitals with protocols for personal protective equipment,2 despite recommendations by Thomas Treibel and colleagues.3 The 1600-bed Tan Tock Seng Hospital, Singapore, is colocated with the 330-bed National Centre for Infectious Diseases, Singapore, which, together, manage most patients with COVID-19 in Singapore. At this hospital, HCWs use fit-tested N95 respirators, eye protection, gloves, and gowns in areas where patients with COVID-19 are treated and wear surgical masks across the campus. Full-Text PDF Asymptomatic health-care worker screening during the COVID-19 pandemic – Authors' replyKevin Fennelly and Christopher Whalen emphasise that health-care workers (HCWs) are at a higher risk of severe acute respiratory syndrome coronavirus 2 infection than are the general population. Angela Chow and colleagues describe their experience in Singapore of very low rates of HCW infections and nosocomial transmission when effective personal protective equipment is implemented. We agree with both perspectives, and our Correspondence1 did not contradict either of these viewpoints. Full-Text PDF