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      Survival analysis of time to SARS-CoV-2 PCR negativisation to optimise PCR prescription in health workers: the Henares COVID-19 healthcare workers cohort study

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          Abstract

          Objectives

          Reverse transcriptase PCR (RT-PCR) is considered the gold standard in diagnosing COVID-19. Infected healthcare workers do not go back to work until RT-PCR has demonstrated that the virus is no longer present in the upper respiratory tract. The aim of this study is to determine the most efficient time to perform RT-PCR prior to healthcare workers’ reincorporation.

          Materials and methods

          This is a cohort study of healthcare workers with RT-PCR-confirmed COVID-19. Data were collected using the medical charts of healthcare workers and completed with a telephone interview. Kaplan-Meier curves were used to determine the influence of several variables on the time to RT-PCR negativisation. The impact of the variables on survival was assessed using the Breslow test. A Cox regression model was developed including the associated variables.

          Results

          159 subjects with a positive RT-PCR out of 374 workers with suspected COVID-19 were included. The median time to negativisation was 25 days from symptom onset (IQR 20–35 days). Presence of IgG, dyspnoea, cough and throat pain were associated with significant longer time to negativisation. Cox logistic regression was used to adjust for confounding variables. Only dyspnoea and cough remained in the model as significant determinants of prolonged negativisation time. Adjusted HRs were 0.68 (0.48–096) for dyspnoea and 0.61 (0.42–0.88) for dry cough.

          Conclusions

          RT-PCR during the first 3 weeks leads to a high percentage of positive results. In the presence of respiratory symptoms, negativisation took nearly 1 week more. Those who developed antibodies needed longer time to negativisate.

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          Most cited references17

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          Outbreak of pneumonia of unknown etiology in Wuhan, China: The mystery and the miracle

          Since December 2019, a total of 41 cases of pneumonia of unknown etiology have been confirmed in Wuhan city, Hubei Province, China. Wuhan city is a major transportation hub with a population of more than 11 million people. Most of the patients visited a local fish and wild animal market last month. At a national press conference held today, Dr Jianguo Xu, an academician of the Chinese Academy of Engineering, who led a scientific team announced that a new‐type coronavirus, tentatively named by World Health Organization as the 2019‐new coronavirus (2019‐nCoV), had caused this outbreak. 1 The 2019‐nCoV has a different coronavirus‐specific nucleic acid sequence from known human coronavirus species, which are similar to some of the beta coronaviruses identified in bats. 2 , 3 The virus‐specific nucleic acid sequences were detected in lung fluid, blood and throat swab samples in 15 patients and the virus that was isolated showed a typical coronavirus appearance under electron microscopy. Further research will be conducted to better understand the new coronavirus to develop antiviral agents and vaccines. 4 We applauded the excellent job that has been done so far. The infection was first described in December. Within 9 days, a special team consisted of physicians, scientists and epidemiologists who ruled out several extremely contagious pathogens including SARS, which killed hundreds of people more than a decade ago, and MERS. This has surely alleviated environmental concerns as Hong Kong authorities had quickly stepped up the disinfection of trains and airplanes and checks of passengers due to this outbreak. Most of the patients visited the fish and wild animal market last month in Wuhan. This fish and wild animal market also sold live animals such as poultry, bats, marmots, and snakes. All patients received prompt supportive treatment in quarantine. Among them, seven patients were in serious condition and one patient died. All of the 42 patients so far confirmed were from China except one Thailand patient who was a traveler from Wuhan. Eight patients have been cured of the disease and were discharged from the hospital last week. The 2019‐nCoV now have been isolated from multiple patients and appears to be the culprit. But the mystery has not been completely solved yet. Until there is a formal published scientific manuscript, the facts can be argued, particularly regarding causality despite these facts having been officially announced. The data collected so far is not enough to confirm the causal relationship between the new‐type coronavirus and the respiratory disease based on classical Koch's postulates or modified ones as suggested by Fredricks and Relman. 5 The viral‐specific nucleic acids were only discovered in 15 patients, and successful virus culture was extremely limited to only a few patients. There remains considerable work to be done to differentiate between colonization, shedding, and infection. Additional strains of the 2019‐nCoV need to be isolated to study their homologies. It is expected that antigens and monoclonal antibodies will be developed so serology can be used to confirm previous and acute infection status. The episode demonstrates further the need for rapid and accurate detection and identification methods that can be used in the local hospitals and clinics bearing the burden of identifying and treating patients. Recently, the Clinical Laboratory Improvement Amendments (CLIA) of 1988 has waived highly sensitive and specific molecular devices known as CLIA‐waived devices so that these devices are gradually becoming available for point of care testing. Finally, the epidemiological similarity between this outbreak and that of SARS in 2002‐2003 6 is striking. SARS was then traced to animal markets 7 and eventually to palm civets. 8 Later bats were identified as animal reservoirs. 9 Could this novel coronavirus be originated from wild animals? The family Coronaviridae includes two subfamilies. 10 One, the subfamily Coronavirinae, contains a substantial number of pathogens of mammals that individually cause a remarkable variety of diseases, including pneumonia. In humans, coronaviruses are among the spectrum of viruses that cause the common cold as well as more severe respiratory disease—specifically SARS and MERS, which are both zoonoses. The second subfamily, Torovirinae, contains pathogens of both terrestrial and aquatic animals. The genus Torovirus includes the type species, equine torovirus (Berne virus), which was first isolated from a horse with diarrhea, and the Breda virus, which was first isolated from neonatal calves with diarrhea. White bream virus from fish is the type species of the genus Bafinivirus. However, there is no evidence so far that the seafood from the fish and animal market caused 2019‐nCoV‐associated pneumonia. This epidemiologic similarity clearly provides a starting point for the further investigation of this outbreak. In the meantime, this fish and animal market has been closed until the epidemiological work determines the animal host of this novel coronavirus. Only then will the miracle be complete.
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            Characteristics of Health Care Personnel with COVID-19 — United States, February 12–April 9, 2020

            As of April 9, 2020, the coronavirus disease 2019 (COVID-19) pandemic had resulted in 1,521,252 cases and 92,798 deaths worldwide, including 459,165 cases and 16,570 deaths in the United States ( 1 , 2 ). Health care personnel (HCP) are essential workers defined as paid and unpaid persons serving in health care settings who have the potential for direct or indirect exposure to patients or infectious materials ( 3 ). During February 12–April 9, among 315,531 COVID-19 cases reported to CDC using a standardized form, 49,370 (16%) included data on whether the patient was a health care worker in the United States; including 9,282 (19%) who were identified as HCP. Among HCP patients with data available, the median age was 42 years (interquartile range [IQR] = 32–54 years), 6,603 (73%) were female, and 1,779 (38%) reported at least one underlying health condition. Among HCP patients with data on health care, household, and community exposures, 780 (55%) reported contact with a COVID-19 patient only in health care settings. Although 4,336 (92%) HCP patients reported having at least one symptom among fever, cough, or shortness of breath, the remaining 8% did not report any of these symptoms. Most HCP with COVID-19 (6,760, 90%) were not hospitalized; however, severe outcomes, including 27 deaths, occurred across all age groups; deaths most frequently occurred in HCP aged ≥65 years. These preliminary findings highlight that whether HCP acquire infection at work or in the community, it is necessary to protect the health and safety of this essential national workforce. Data from laboratory-confirmed COVID-19 cases voluntarily reported to CDC from 50 states, four U.S. territories and affiliated islands, and the District of Columbia, during February 12–April 9 were analyzed. Cases among persons repatriated to the United States from Wuhan, China, and the Diamond Princess cruise ship during January and February were excluded. Public health departments report COVID-19 cases to CDC using a standardized case report form* that collects information on patient demographics, whether the patient is a U.S. health care worker, symptom onset date, specimen collection dates, history of exposures in the 14 days preceding illness onset, COVID-19 symptomology, preexisting medical conditions, and patient outcomes, including hospitalization, intensive care unit (ICU) admission, and death. HCP patient health outcomes, overall and stratified by age, were classified as hospitalized, hospitalized with ICU admission, and deaths. The lower bound of these percentages was estimated by including all cases within each age group in the denominators. Upper bounds were estimated by including only those cases with known information on each outcome as denominators. Data reported to CDC are preliminary and can be updated by health departments over time. The upper quartile of the lag between onset date and reporting to CDC was 10 days. Because submitted forms might have missing or unknown information at the time of report, all analyses are descriptive, and no statistical comparisons were performed. Stata (version 15.1; StataCorp) and SAS (version 9.4; SAS Institute) were used to conduct all analyses. Among 315,531 U.S. COVID-19 cases reported to CDC during February 12–April 9, data on HCP occupational status were available for 49,370 (16%), among whom 9,282 (19%) were identified as HCP (Figure). Data completeness for HCP status varied by reporting jurisdiction; among 12 states that included HCP status on >80% of all reported cases and reported at least one HCP patient, HCP accounted for 11% (1,689 of 15,194) of all reported cases. FIGURE Daily number of COVID-19 cases, by date of symptom onset, among health care personnel and non-health care personnel (N = 43,986)* , † — United States, February 12–April 9, 2020 Abbreviation: COVID-19 = coronavirus disease 2019. * Onset date was calculated for 5,892 (13%) cases where onset date was missing. This was done by subtracting 4 days (median interval from symptom onset to specimen collection date) from the date of earliest specimen collection. Cases with unknown onset and specimen collection dates were excluded. † Ten-day window is used to reflect the upper quartile in lag between the date of symptom onset and date reported to CDC. The figure is a bar chart showing the number of reported COVID-19 cases among health care personnel and non-health care personnel (N = 43,986), by date of illness onset, in the United States during February 12–April 9, 2020. Among the 8,945 (96%) HCP patients reporting age, the median was 42 years (IQR = 32–54 years); 6,603 (73%) were female (Table 1). Among the 3,801 (41%) HCP patients with available data on race, a total of 2,743 (72%) were white, 801 (21%) were black, 199 (5%) were Asian, and 58 (2%) were other or multiple races. Among 3,624 (39%) with ethnicity specified, 3,252 (90%) were reported as non-Hispanic/Latino and 372 (10%) as Hispanic/Latino. At least one underlying health condition † was reported by 1,779 (38%) HCP patients with available information. TABLE 1 Demographic characteristics, exposures, symptoms, and underlying health conditions among health care personnel with COVID-19 (N = 9,282) — United States, February 12–April 9, 2020 Characteristic (no. with available information) No. (%) Age group (yrs) (8,945) 16–44 4,898 (55) 45–54 1,919 (21) 55–64 1,620 (18) ≥65 508 (6) Sex (9,067) Female 6,603 (73) Male 2,464 (27) Race (3,801) Asian 199 (5) Black 801 (21) White 2,743 (72) Other* 58 (2) Ethnicity (3,624) Hispanic/Latino 372 (10) Non-Hispanic/Latino 3,252 (90) Exposures†,§ (1,423) Only health care exposure 780 (55) Only household exposure 384 (27) Only community exposure 187(13) Multiple exposure settings¶ 72 (5) Symptoms reported§,** (4,707) Fever, cough, or shortness of breath†† 4,336 (92) Cough 3,694 (78) Fever§§ 3,196 (68) Muscle aches 3,122 (66) Headache 3,048 (65) Shortness of breath 1,930 (41) Sore throat 1,790 (38) Diarrhea 1,507 (32) Nausea or vomiting 923 (20) Loss of smell or taste¶¶ 750 (16) Abdominal pain 612 (13) Runny nose 583 (12) Any underlying health condition§,*** (4,733) 1,779 (38) Abbreviation: COVID-19 = coronavirus disease 2019. * “Other” includes patients who were identified as American Indian or Alaska Native (16), Native Hawaiian or Other Pacific Islander (22), or two or more races (20). † Cases were included in the denominator if the patient reported a known contact with a laboratory-confirmed COVID-19 patient within the 14 days before illness onset in a health care, household, or community setting. § Responses include data from standardized fields supplemented with data from free-text fields. ¶ Includes all patients with contact reported in more than one of these settings: health care, household, and community. ** Cases were included in the denominator if the patient had a known symptom status for fever, cough, shortness of breath, nausea or vomiting, and diarrhea. HCP with mild or asymptomatic infections might have been less likely to be tested, thus less likely to be reported. †† Includes all patients with at least one of these symptoms. §§ Patients were included if they had information for either measured or subjective fever variables and were considered to have a fever if “yes” was indicated for either variable. ¶¶ Symptom data on loss of smell or taste was extracted only from free-text symptom fields, thus the proportion with this symptom is likely an underestimate. *** Preexisting medical conditions and other risk factors (yes, no, or unknown) included the following: chronic lung disease (inclusive of asthma, chronic obstructive pulmonary disease, and emphysema); diabetes mellitus; cardiovascular disease; chronic renal disease; chronic liver disease; immunocompromised condition; neurologic disorder, neurodevelopmental or intellectual disability; pregnancy; current smoking status; former smoking status; or other chronic disease. Among 1,423 HCP patients who reported contact with a laboratory-confirmed COVID-19 patient in either health care, household, or community settings, 780 (55%) reported having such contact only in a health care setting within the 14 days before their illness onset; 384 (27%) reported contact only in a household setting; 187 (13%) reported contact only in a community setting; 72 (5%) reported contact in more than one of these settings. Among HCP patients with data available on a core set of signs and symptoms, § a total of 4,336 (92%) reported having at least one of fever, cough, shortness of breath. Two thirds (3,122, 66%) reported muscle aches, and 3,048 (65%) reported headache. Loss of smell or taste was written in for 750 (16%) HCP patients as an “other” symptom. Among HCP patients with data available on age and health outcomes, 6,760 (90%) were not hospitalized, 723 (8%–10%) were hospitalized, 184 (2%–5%) were admitted to an ICU, and 27 (0.3%–0.6%) died (Table 2). Although only 6% of HCP patients were aged ≥65 years, 10 (37%) deaths occurred among persons in this age group. TABLE 2 Hospitalizations,* intensive care unit (ICU) admissions, † and deaths, § by age group among health care personnel with COVID-19 — United States, February 12–April 9, 2020 Age group¶ (yrs) (no. of cases) Outcome, no. (%)** Hospitalization†† ICU admission Death 16–44 (4,898) 260 (5.3–6.4) 44 (0.9–2.2) 6 (0.1–0.3) 45–54 (1,919) 178 (9.3–11.1) 51 (2.7–6.3) 3 (0.2–0.3) 55–64 (1,620) 188 (11.6–13.8) 54 (3.3–7.5) 8 (0.5–1.0) ≥65 (508) 97 (19.1–22.3) 35 (6.9–16.0) 10 (2.0–4.2) Total (8,945) 723 (8.1–9.7) 184 (2.1–4.9) 27 (0.3–0.6) Abbreviation: COVID-19 = coronavirus disease 2019. * Hospitalization status known for 7,483 (84%) patients. † ICU status known for 3,739 (42%) patients. § Death outcomes known for 4,407 (49%) patients. ¶ Age status known for 8,945 (96%) patients. ** Lower bound of range = number of persons hospitalized, admitted to ICU, or who died among total in age group; upper bound of range = number of persons hospitalized, admitted to ICU, or who died among total in age group with known hospitalization status, ICU admission status, or death. †† Hospitalization status includes hospitalization with or without ICU admission. Discussion As of April 9, 2020, a total of 9,282 U.S. HCP with confirmed COVID-19 had been reported to CDC. This is likely an underestimation because HCP status was available for only 16% of reported cases nationwide. HCP with mild or asymptomatic infections might also have been less likely to be tested, thus less likely to be reported. Overall, only 3% (9,282 of 315,531) of reported cases were among HCP; however, among states with more complete reporting of HCP status, HCP accounted for 11% (1,689 of 15,194) of reported cases. The total number of COVID-19 cases among HCP is expected to rise as more U.S. communities experience widespread transmission. Compared with reports of COVID-19 patients in the overall populations of China and Italy ( 4 , 5 ), reports of HCP patients in the United States during February 12–April 9 were slightly younger, and a higher proportion were women; this likely reflects the age and sex distributions among the U.S. HCP workforce. Race and ethnicity distributions among HCP patients reported to CDC are different from those in the overall U.S. population but are more similar to those in the HCP workforce. ¶ , ** Among HCP patients who reported having contact with a laboratory-confirmed COVID-19 patient in health care, household, or community settings, the majority reported contact that occurred in health care settings. However, there were also known exposures in households and in the community, highlighting the potential for exposure in multiple settings, especially as community transmission increases. Further, transmission might come from unrecognized sources, including presymptomatic or asymptomatic persons ( 6 , 7 ). Together, these exposure possibilities underscore several important considerations for prevention. Done alone, contact tracing after recognized occupational exposures likely will fail to identify many HCP at risk for developing COVID-19. Additional measures that will likely reduce the risk for infected HCP transmitting the virus to colleagues and patients include screening all HCP for fever and respiratory symptoms at the beginning of their shifts, prioritizing HCP for testing, and ensuring options to discourage working while ill (e.g., flexible and nonpunitive medical leave policies). Given the evidence for presymptomatic and asymptomatic transmission ( 7 ), covering the nose and mouth (i.e., source control) is recommended in community settings where other social distancing measures are difficult to maintain. †† Assuring source control among all HCP, patients, and visitors in health care settings is another promising strategy for further reducing transmission. Even if everyone in a health care setting is covering their nose and mouth to contain their respiratory secretions, it is still critical that, when caring for patients, HCP continue to wear recommended personal protective equipment (PPE) (e.g., gown, N95 respirator [or facemask if N95 is not available], eye protection, and gloves for COVID-19 patient care). Training of HCP on preventive measures, including hand hygiene and PPE use, is another important safeguard against transmission in health care settings. Among HCP with COVID-19 whose age status was known, 8%–10% were reported to be hospitalized. This is lower than the 21%–31% of U.S. COVID-19 cases with known hospitalization status described in a recent report ( 8 ) and might reflect the younger median age (42 years) of HCP patients compared with that of reported COVID-19 patients overall, as well as prioritization of HCP for testing, which might identify less severe illness. Similar to earlier findings ( 8 ), increasing age was associated with a higher prevalence of severe outcomes, although severe outcomes, including death, were observed in all age groups. Preliminary estimates of the prevalence of underlying health conditions among all patients with COVID-19 reported to CDC through March 2020 ( 9 ) suggested that 38% had at least one underlying condition, the same percentage found in this HCP patient population. Older HCP or those with underlying health conditions ( 8 , 9 ) should consider consulting with their health care provider and employee health program to better understand and manage their risks regarding COVID-19. The increased prevalence of severe outcomes in older HCP should be considered when mobilizing retired HCP to increase surge capacity, especially in the face of limited PPE availability §§ ; one consideration is preferential assignment of retired HCP to lower-risk settings (e.g., telemedicine, administrative assignments, or clinics for non–COVID-19 patients). The findings in this report are subject to at least five limitations. First, approximately 84% of patients were missing data on HCP status. Thus, the number of cases in HCP reported here must be considered a lower bound because additional cases likely have gone unidentified or unreported. Second, among cases reported in HCP, the amount of missing data varied across demographic groups, exposures, symptoms, underlying conditions, and health outcomes; cases with available information might differ systematically from those without available information. Therefore, additional data are needed to confirm findings about the impact of potentially important factors (e.g., disparities in race and ethnicity or underlying health conditions among HCP). Third, additional time will be necessary for full ascertainment of outcomes, such as hospitalization status or death. Fourth, details of occupation and health care setting were not routinely collected through case-based surveillance and, therefore, were unavailable for this analysis. Finally, among HCP patients who reported contact with a confirmed COVID-19 patient in a health care setting, the nature of this contact, including whether it was with a patient, visitor, or other HCP, and the details of potential occupational exposures, including whether HCP were unprotected (i.e., without recommended PPE) or were present during high risk procedures (e.g., aerosol-generating procedures) are unknown ( 10 ). It is critical to make every effort to ensure the health and safety of this essential national workforce of approximately 18 million HCP, both at work and in the community. Surveillance is necessary for monitoring the impact of COVID-19-associated illness and better informing the implementation of infection prevention and control measures. Improving surveillance through routine reporting of occupation and industry not only benefits HCP, but all workers during the COVID-19 pandemic. Summary What is already known about this topic? Limited information is available about COVID-19 infections among U.S. health care personnel (HCP). What is added by this report? Of 9,282 U.S. COVID-19 cases reported among HCP, median age was 42 years, and 73% were female, reflecting these distributions among the HCP workforce. HCP patients reported contact with COVID-19 patients in health care, household, and community settings. Most HCP patients were not hospitalized; however, severe outcomes, including death, were reported among all age groups. What are the implications for public health practice? It is critical to ensure the health and safety of HCP, both at work and in the community. Improving surveillance through routine reporting of occupation and industry not only benefits HCP, but all workers during the COVID-19 pandemic.
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              COVID-19: the case for health-care worker screening to prevent hospital transmission

              The outbreak of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has placed unprecedented strain on health-care services worldwide, leading to more than 100 000 deaths worldwide, as of April 15, 2020. 1 Most testing for SARS-CoV-2 aims to identify current infection by molecular detection of the SARS-CoV-2 antigen; this involves a RT-PCR of viral RNA in fluid, typically obtained from the nasopharynx or oropharynx. 2 The global approach to SARS-CoV-2 testing has been non-uniform. In South Korea, testing has been extensive, with emphasis on identifying individuals with respiratory illness, and tracing and testing any contacts. Other countries (eg, Spain) initially limited testing to individuals with severe symptoms or those at high risk of developing them. Here we outline the case for mass testing of both symptomatic and asymptomatic health-care workers (HCWs) to: (1) mitigate workforce depletion by unnecessary quarantine; (2) reduce spread in atypical, mild, or asymptomatic cases; and (3) protect the health-care workforce. Staff shortages in health care are significant amidst the global effort against coronavirus disease 2019 (COVID-19). In the UK, guidance for staffing of intensive care units has changed drastically, permitting specialist critical care nurse-to-patient ratios of 1:6 when supported by non-specialists (normally 1:1) and one critical care consultant per 30 patients (formerly 1:8–1:15). 3 Fears of the impact of this shortage have led to other measures that would, in normal circumstances, be considered extreme: junior doctors’ rotations have been temporarily halted during the outbreak; annual leave for staff has been delayed; and doctors undertaking research activities have been redeployed. Workforce depletion will not only affect health care; the Independent Care Group, representing care homes in the UK, has suggested that social care is already “at full stretch”, 4 with providers calling for compulsory testing of social and health workers to maintain staffing. In spite of this, a lack of effective testing has meant that a large number of HCWs are self-isolating (125 000 HCWs, according to one report 5 ). In one small sample, only one in seven self-isolating HCWs were found to have the virus. 6 A letter to National Health Service (NHS) Trust executives on April 12, 2020, outlined that priority is being given to staff in critical care, emergency departments, and ambulance services to prevent the impact of absenteeism in those areas. 7 Increased testing capacity will enable all staff who are self-isolating unnecessarily to bolster a depleted workforce. Asymptomatic HCWs are an underappreciated potential source of infection and worthy of testing. The number of asymptomatic cases of COVID-19 is significant. In a study of COVID-19 symptomatic and asymptomatic infection on the Diamond Princess cruise ship, 328 of the 634 positive cases (51·7%) were asymptomatic at the time of testing. 8 Estimated asymptomatic carriage was 17·9%. 8 Among 215 obstetric cases in New York City, 29 (87·9%) of 33 positive cases were asymptomatic, 9 whereas China's National Health Commission 10 recorded on April 1, 2020, that 130 (78%) of 166 positive cases were asymptomatic. Moreover, transmission before the onset of symptoms has been reported11, 12, 13, 14 and might have contributed to spread among residents of a nursing facility in Washington, USA. 15 Furthermore, evidence from modelled COVID-19 infectiousness profiles suggests that 44% of secondary cases were infected during the presymptomatic phase of illnesses from index cases, 16 whereas a study of COVID-19 cases in a homeless shelter in Boston, MA, USA, implies that individual COVID-19 symptoms might be uncommon and proposed universal testing irrespective of symptomatic burden. 17 Substantial asymptomatic transmission might also mean that current estimates of the basic reproduction number, R0, for COVID-19 are inaccurate. 18 HCW testing could reduce in-hospital transmission. In a retrospective, single-centre study in Wuhan, 41% of 138 patients were thought to have acquired infection in hospital. 19 At the Royal Gwent Hospital in Newport, Wales, approximately half of the emergency room workforce have tested positive. 20 Blanket testing near Venice, Italy, helped to identify asymptomatic cases and might have helped eliminate SARS-CoV-2 in a village. 21 Moreover, asymptomatic and presymptomatic HCWs continue to commute to places of work where personal protective equipment (PPE) might be suboptimal. This disease spread could, in turn, propagate out of hospitals: during a period of lockdown asymptomatic COVID-19 carriage among hospital staff could conceivably act as a potent source of ongoing transmission. Protecting the health of HCWs is paramount when staffing is limited. As well as by the provision of adequate PPE, the wellbeing of HCWs can be promoted by ensuring that infected colleagues are promptly tested and isolated. The scale of this problem is not yet fully understood, nor is the full potential for asymptomatic and presymptomatic HCWs to transmit infection to patients who do not have COVID-19, other HCWs, or the public. However, given that asymptomatic transmission has been documented, utmost caution is urged.11, 12, 13, 14 Our own NHS Trust at University College London Hospitals, London, UK, will soon be testing asymptomatic HCWs. In partnership with the Francis Crick Institute in London, UK, where COVID-19 testing will be performed, this initiative is an attempt to further limit nosocomial transmission. It could also alleviate a critical source of anxiety for HCWs. 22 A healthy, COVID-19-free workforce that is not burned out will be an asset to the prolonged response to the COVID-19 crisis. As testing facilities increase in number and throughput in the coming weeks, testing should aim to accommodate weekly or fortnightly screening of HCWs working in high-risk areas. There is a powerful case in support of mass testing of both symptomatic and asymptomatic HCWs to reduce the risk of nosocomial transmission. At the time of writing, the UK is capable of performing 18 000 tests per day, 23 with the Health Secretary targeting a capacity of 100 000 tests per day by the end of April, 2020. Initially, the focus of testing was patients, with NHS England stating only 15% of available testing would be used to test NHS staff. 24 Although this cap has been lifted, symptomatic HCWs, rather than asymptomatic HCWs, are currently prioritised in testing. This approach could mean that presymptomatic HCWs who are capable of transmitting the virus are not being tested; if they were tested and found to be COVID-19 positive, they could be advised to isolate and await the onset of symptoms or, if no symptoms develop, undergo repeat testing. As countries seek to flatten the growth phase of COVID-19, we see a significant opportunity in expanding testing among HCWs; this will be critical when pursuing an exit strategy from strict lockdown measures that curb spread of the virus.
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                Author and article information

                Journal
                Occup Environ Med
                Occup Environ Med
                oemed
                oem
                Occupational and Environmental Medicine
                BMJ Publishing Group (BMA House, Tavistock Square, London, WC1H 9JR )
                1351-0711
                1470-7926
                April 2021
                28 April 2021
                : oemed-2020-106903
                Affiliations
                [1 ]departmentOphthalmology , Henares University Hospital , Coslada, Madrid, Spain
                [2 ]departmentFacultad de Medicina , Universidad Francisco de Vitoria , Pozuelo de Alarcon, Comunidad de Madrid, Spain
                [3 ]departmentAllergy and Immunology , Henares University Hospital , Coslada, Madrid, Spain
                [4 ]departmentRheumatology , Henares University Hospital , Coslada, Madrid, Spain
                [5 ]departmentENT , Henares University Hospital , Coslada, Madrid, Spain
                [6 ]departmentICU , Severo Ochoa University Hospital , Leganés, Madrid, Spain
                [7 ]departmentOphthalmology , Hospital Ramón y Cajal , Madrid, Madrid, Spain
                [8 ]departmentOphthalmology , Clínica Rementería , Madrid, Madrid, Spain
                Author notes
                [Correspondence to ] Dr Julio González Martin-Moro, Ophthalmology, Henares University Hospital, Coslada 28080, Spain; juliogazpeitia@ 123456gmail.com
                Author information
                http://orcid.org/0000-0002-8056-2630
                Article
                oemed-2020-106903
                10.1136/oemed-2020-106903
                8103550
                33910984
                66413ca7-601b-4733-8827-edda1b95653f
                © Author(s) (or their employer(s)) 2021. No commercial re-use. See rights and permissions. Published by BMJ.

                This article is made freely available for use in accordance with BMJ’s website terms and conditions for the duration of the covid-19 pandemic or until otherwise determined by BMJ. You may use, download and print the article for any lawful, non-commercial purpose (including text and data mining) provided that all copyright notices and trade marks are retained.

                History
                : 17 July 2020
                : 31 January 2021
                : 06 March 2021
                Funding
                Funded by: Fundación para la Investigación e Innovación Biomédica del Hospital Universitario Infanta Sofía y Hospital Universitario del Henares.;
                Award ID: FHH20/COVID05
                Categories
                Workplace
                2474
                Original research
                Custom metadata
                free

                Occupational & Environmental medicine
                virology,risk assessment,investigation of outbreaks of illness,immunology,hygiene / occupational hygiene

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