Letters2 June 2020

COVID-19 and the Risk to Health Care Workers: A Case Report

    Author, Article, and Disclosure Information

    Background: Little is known about the effectiveness of personal protective equipment for health care workers who take care of patients infected with the novel coronavirus (SARS-CoV-2) that recently originated in China and has spread globally (1, 2).

    Objective: To describe the clinical outcome of health care workers who took care of a patient with severe pneumonia before the diagnosis of COVID-19 was known.

    Case Report: The patient was a middle-aged man with diabetes mellitus and hyperlipidemia who was hospitalized in February 2020 for community-acquired pneumonia. He had not traveled recently to China nor had had contact with anyone known to have COVID-19. He required supplemental oxygen on admission; the following day, he developed respiratory distress that required endotracheal intubation by the emergency airway team and mechanical ventilation in the intensive care unit (ICU). He was transferred to the ICU for intubation and had a difficult intubation that required use of a video laryngoscope and an airway bougie. He improved clinically after 3 days of mechanical ventilation and was subsequently extubated to noninvasive ventilation.

    On the day that the patient was extubated, a nasopharyngeal swab was sent as part of COVID-19 surveillance, and it was positive for SARS-CoV-2 on polymerase chain reaction (PCR) assay (3). Two other swabs obtained on subsequent days tested positive for SARS-CoV-2.

    On the basis of contact tracing, 41 health care workers were identified as having exposure to aerosol-generating procedures for at least 10 minutes at a distance of less than 2 meters from the patient. The aerosol-generating procedures included endotracheal intubation, extubation, noninvasive ventilation, and exposure to aerosols in an open circuit (4). All 41 health care workers were placed under home isolation for 2 weeks, with daily monitoring for cough, dyspnea, and myalgia and twice-daily temperature measurements. In addition, they had nasopharyngeal swabs scheduled on the first day of home isolation, which could have been day 1, 2, 4, or 5 after last exposure to patient, and a second swab scheduled on day 14 after their last exposure. The swabs were tested for SARS-CoV-2 by using a PCR assay. None of the exposed health care workers developed symptoms, and all PCR tests were negative (Table).

    Table. Number of Nasopharyngeal Swabs in Exposed Health Care Workers, by Type of Procedure, Day After Last Exposure, and Type of Mask*

    Discussion: The primary route for the spread of COVID-19 is thought to be through aerosolized droplets that are expelled during coughing, sneezing, or breathing, but there also are concerns about possible airborne transmission. In the situation we describe, 85% of health care workers were exposed during an aerosol-generating procedure while wearing a surgical mask, and the remainder were wearing N95 masks. That none of the health care workers in this situation acquired infection suggests that surgical masks, hand hygiene, and other standard procedures protected them from being infected. Our observation is consistent with previous studies that have been unable to show that N95 masks were superior to surgical masks for preventing influenza infection in health care workers (5). We emphasize, however, that nearly all experts recommend that health care workers wear an N95 mask or equivalent equipment while performing an aerosol-generating procedure.

    We recognize the limitations of this single case report and acknowledge that additional studies are necessary to determine how best to protect health care workers from becoming infected with SARS-CoV while they are providing care for patients with COVID-19.



    Kangqi Ng, Jagadesan Raghuram29 April 2020
    Authors' Response
    We thank Vivian et al for for highlighting the multiple factors that influence viral transmission to HCWs. We agree that each AGP has different aerosolization risks (1). As provided in our article, 10 out of 41 HCWs were exposed to patient during intubation, which has been shown to be of high risk in various literature (2). Viral shedding is one of the factors that affect transmission, but it is variable with various viral loads at different timelines in the disease (3). While there are factors that are difficult to determine, our experience highlights the importance of personal protective equipment and hand hygiene in protecting HCWs.
    We thank Birati et al. and Dai et al for commenting on appropriate personal protective precautions. We also agree that protecting our HCWs is of paramount concern. As previously emphasized, we believe that the combination of surgical masks for all HCWs in all clinical areas in addition to strict hand hygiene and additional PPE requirements for HCWs taking care of suspected patients are of utmost importance.
    Finally, we would like to emphasize that the virus can be found on multiple surfaces including gown and gloves (3). Therefore, while the spotlight has been on the type of masks, we should never forget the need for good hand hygiene.


    1. Hui DS, Chan MT, Chow B. Aerosol dispersion during various respiratory therapies: a risk assessment model of nosocomial infection to health care workers. Hong Kong Med J. 2014;20 Suppl 4:9–13.
    2. Tran K, Cimon K, Severn M et al. (2012) Aerosol generating procedures and risk of transmission of acute respiratory infections to healthcare workers: A systematic review. PLoS ONE, 7 (4):1-8.
    3. He, X., Lau, E.H.Y., Wu, P. et al. Temporal dynamics in viral shedding and transmissibility of COVID-19. Nat Med (2020). https://doi.org/10.1038/s41591-020-0869-5
    4. Phan LT, Sweeney D, Maita D, et al. Respiratory viruses on personal protective equipment and bodies of healthcare workers. Infect Control Hosp Epidemiol. 2019;40(12):1356–1360. doi:10.1017/ice.2019.298
    Kangqi Ng, Troy Hai Kiat Puar; Jessica Li Shan Quah; Yu Jun Wong, Thean Yen Tan; Jagadesan Raghuram 24 March 2020
    Authors' Response
    We thank Karolina et al. for highlighting the need to balance pre-emptive quarantine of asymptomatic exposed health care workers (HCWs) and sustainable healthcare. As reliable data on the risk of asymptomatic transmission of this novel virus was unknown, we elected to quarantine all exposed HCWs until we were certain that they were not infected [1]. Our strategy was disease containment to prevent further spread, as protecting HCWs prevents nosocomial transmission [2]. Such an approach has been adopted in areas which had “flatten the curve” such as Korea and Taiwan. We acknowledge this approach may strain the existing health care resources. However, it is also paramount to ensure the safety and trust of our HCWs, especially with the mounting pressure from the increased work demand, inadequate resources and stigmatization from the community [3].
    To address Lee et al. query, none of the HCWs involved in endotracheal intubation used eye shields. Our recommendation for HCWs during aerosol generating procedures (AGP) for suspected cases, included a powered-air purifying respirator, N95 mask, gloves and a full-body gown. For non-AGPs for suspected cases, eye protection, N95 mask, gloves, and a full-body gown were recommended.
    We thank Siu et al. for the comments, and we acknowledge that protecting health care workers (HCWs) with personal protective equipment (PPE) is paramount. It is important that readers were aware that during the exposure to our index patient, Singapore was at Disease Outbreak Response System Condition (DORSCON) alert level yellow [4]. However, without a travel history to China, or contact with COVID-19 patient, our patient did not meet national case definitions for COVID-19 testing. Following admission, enhanced testing for COVID-19 was initiated based on a revised national advisory for surveillance testing, and our patient subsequently found to be positive for COVID-19, 4 days after admission. During the early phase of the COVID-19 pandemic, several measures were set in place throughout Singapore, including ensuring excellent hand hygiene among HCWs, frequent disinfection of common areas, educating HCWs on PPE and restricting non-essential hospital visits for patients. Our hospital enforced standard droplet precautions and mandated the use of surgical masks in all clinical areas, with additional appropriate PPE (as stated above) when caring for suspect COVID-19 patients. We believe these measures collectively protected our HCWs in this exposure [5].
    We appreciate Sedgwick et al. for highlighting a trial demonstrating the continuous use of N95 mask to prevent respiratory infections in HCWs. The practical use of PPE during a global pandemic, especially in a resource-limited setting, has been a point of debate. We must emphasize that adequate protection of HCWs should not be a debate on surgical masks or N95 masks alone, but rather a continuous, strict adherence to all protective measures, whenever possible. Finally, we emphasize that all institutions have the responsibility to equip all HCWs, our frontline warrior, with adequate PPE, in fighting this long-haul war against COVID-19.

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    1. Hu Z, Song C, Xu C et al. Clinical characteristics of 24 asymptomatic infections with COVID-19 screened among close contacts in Nanjing, China. Sci China Life Sci 2020. Doi: 10.1007/s11427-020-1661-4
    2. Cheng VCC, Wong S, Chen JHK et al. Escalating infection control response to the rapidly evolving epidemiology of the Coroavirus disease 2019 (COVID-19) due to SARS-COV-2 in Hong Kong. Infect Control Hosp Epidemiol 2020; 5:1-24
    3. Su TP, Lien TC, Yang YC et al. Prevalence of psychiatric morbidity and psychological adaptation of the nurse in a structured SARS caring unit during outbreak: a prospective and periodic assessment study in Taiwan. J Psychiatr Res 2007; 41: 119-30
    4. What do the different DORSCON levels mean. The colours describe the current disease outbreak situation and what needs to be done. https://www.gov.sg/article/what-do-the-different-dorscon-levels-mean. Accessed on 20 March 2020.
    5. Atul Gawande. Keeping the Coronavirus from Infecting Health-Care Workers. What Singapore’s and Hong Kong’s success is teaching us about the pandemic. https://www.newyorker.com/news/news-desk/keeping-the-coronavirus-from-infecting-health-care-workers. Accessed 23 March 2020.
    Lau CS, TC Aw30 April 2020
    The use of protective equipment in intubation of COVID-19 patients
    Adequate personal protective equipment (PPE) is a prerequisite for the emergency airway management of respiratory distress (1, 2). We are heartened and reassured that the health care workers (HCWs) in the case report recently described (3) did not contract SARS-CoV-2. In this report 6 HCW performed/assisted in a difficult intubation (including video laryngoscopy and airway bougie) wearing N95 masks and gloves only in February 2020. The patient diagnosed as community acquired pneumonia had no travel history to China. On a quick extubation 3 days later by 2 HCW wearing surgical masks the PCR test for SARS-CoV-2 was positive. All these 8 staff and 33 others in the unit were isolated for 14 days and tested negative for SARS-Cov-2 on two occasions. In another recent report (4) describing a simulation study using manikins in the emergency department, fluorescent markers demonstrated that aerosols can still contaminate exposed areas (skin and hair) and shoes of attending HCWs despite the use of recommended PPE measures (eye protection, N95 respirator, gloves and gown). They suggested that prevailing PPE recommendations (CDC, WHO) may not be fully adequate. We are aware of another instance in USA where the use of basic PPE resulted in no COVID-19 transmission to HCW (5). A woman returned from Wuhan in mid-January 2020 and was admitted for pneumonia and subsequently tested positive for SARS-CoV-2. Out of 195 HCWs who had contact with this patient 83 were not wearing full PPE and none of them contracted Cov-19.
    While it is fortunate that basic PPE was adequate in both these instances. It is heartening and reassuring that learned societies have since augmented PPE standards in March 16 (1) and March 27 (2) in the face of COVID-19. While larger studies are awaited to establish the true infectivity of COVID-19 in intubation and other aerosol-generating procedures, the use of the N95 mask appears to be vital in the prevention of transmission of infection to HCWs. Further evidence-based research is also required before we can prove that SARS-CoV-2 is able to initiate infection at exposed skin in the face and neck. However, the full recommended PPE set with goggles, face shield, hair and foot coverings should always be used. Of course, strict hand hygiene remains paramount.

    (1) Brewster DJ, Chrimes NC, Do TBT, et al. Consensus statement: Safe Airway Society principles of airway management and tracheal intubation specific to the COVID-19 adult patient group. Med J Aust [Published online March 16. 2020]. Accessed April 30, 2020. https://www.mja.com.au/system/files/2020-04/Preprint%20Brewster%20updated%201%20April%202020.pdf
    (2) Cook TM, El-boghdadly K, McGuire B, et al. Consensus Guidelines for Managing the Airway in Patients With COVID-19: Guidelines From the Difficult Airway Society, the Association of Anaesthetists the Intensive Care Society, the Faculty of Intensive Care Medicine and the Royal College of Anaesthetists. Anaesthesia [Published online March 27, 2020]. Doi: 10.1111/anae.15054.
    (3) Ng K, Poon BH, Puar HK, et al. COVID-19 and the risk to health care workers: a case report.. Ann Intern Med [Published online March 16, 2020]. Doi: 10.7326/L20-0175.
    (4) Feldman O, Meir M, Shavit D, Idelman R, Shavit I. Exposure to a surrogate measure of contamination from simulated patients by emergency department personnel wearing personal protective equipment. JAMA [Published online April 27, 2020]. Doi: 10.1001/jama.2020.6633.
    (5) Ghinai I, McPherson TD, Hunter JC, et al. First Known Person-To-Person Transmission of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) in the USA. Lancet [Published online March 13, 2020]. Doi: 10.1016/S0140-6736(20)30607-3.
    Ting-Hsuan Dai, Wang-Huei Sheng, Chia-Yen Dai14 April 2020
    A huge threat to health-care resource and global public health systems: COVID-19 of healthcare workers
    Ng et al. described none of the 41 health care workers (HCWs) getting coronavirus disease 2019 (COVID-19) after taking care of a male patient before his confirmed diagnosis of COVID-19 (1). We have to emphasize that hospital populations are at significantly increased risk for COVID-19. With the presence of the healthcare-associated infection (HAI) of 2019 novel coronavirus (2019-nCoV) which may extremely damage the health-care resources reported in many countries globally, such as more than 150 employees at four Boston hospitals have tested positive for coronavirus reported recently (2), it’s imperative to consummate a system protecting HCWs. With the previous experiences of the SARS-CoV outbreak in 2003 and mortality of Taiwanese HCWs caused by HAI, the Taiwanese government has established a system for hospital preparedness for highly infectious diseases and measures to curb infection outside and inside the healthcare facilities earlier (3). Until April 14, 2020, 393 laboratory-confirmed patients, significantly less than other countries were reported in Taiwan with two deaths after tests for 45,890 individuals (4). Currently, one nosocomial infection reported form one patient in Taiwan resulting in three nurses and one cleaner staff getting infected diagnosed 8 days ago after testing for 94 hospital personnel who have more close contacts with the index patient (4). Although all the 4 HCWs have contact history with this case, it is indeed a crisis that firstly the quarantine of the other HCWs who have contacts with the patients and these sick personnel will make the manpower of the health caring shortage. Fortunately, there is another nosocomial infection noted till now in Taiwan. With continuously increasing patient numbers reported in European countries and the United States, calling back the retired HCWs has been considered for the encountering shortage of manpower. Fewer patient numbers in Taiwan is as a result of effective measures for preventing an outbreak in communities and health care facilities.
    As the recent report describing the quick response to COVID-19 in Taiwan (5), Taiwan’s experience by far provides an exemplary model in earlier fighting COVID-19, particularly the nosocomial infection, and deserves to share around the world. Wearing masks is universally recommended for HCWs. With the community infection and transmission, all measures trying to keep the HCWs, especially in the internal medicine and healthcare facilities safe are crucial and fundamental for the global combating of the huge threat to global public health and the medical system.

    1. Ng K, Poon BH, Kiat Puar TH, Shan Quah JL, Loh WJ, Wong YJ, et al. COVID-19 and the Risk to Health Care Workers: A Case Report. Ann Intern Med. 2020. doi: 10.7326/L20-0175.
    2. https://edition.cnn.com/2020/03/26/health/boston-coronavirus-hospitals-employees-test-positive/index.html
    3. Kao HY, Ko HY, Guo P, Chen CH, Chou SM. Taiwan's Experience in Hospital
    Preparedness and Response for Emerging Infectious Diseases. Health Secur
    4. Taiwan Center for Disease Control. https://www.cdc.gov.tw/En
    5. Wang CJ, Ng CY, Brook RH. Response to COVID-19 in Taiwan. Big Data Analytics,
    New Technology, and Proactive Testing. JAMA. (Published online March 3, 2020.)
    Yosefa Birati, Supriya Shore, Jeremy A. Mazurek, Lee R Goldberg and Edo Y. Birati.5 April 2020
    Appropriate Precautions for Healthcare Providers in the Era of COVID-19
    Infection of healthcare providers (HCP) may have a tremendous effect on the normal function of every health care system. Ng et al. described a case of massive exposure of 41 HCP to a single COVID patient resulting in a need for 2 weeks’ isolation of these providers [1]. In the current era, where the health system worldwide is handling high volume of patients with minimal manpower reserve, this may be detrimental.
    The field of occupational infection prevention and control for healthcare providers (HCP) has evolved over the years to promote universal safety for both HCP and individuals seeking medical care. More than thirty-three years ago HCP handled blood samples without using gloves or other personal protective equipment (PPE), and these precautions were used only for patients with known blood-borne infections. It was only in 1987 that the Centers for Disease Control (CDC) announced recommendations on universal precautions, stating that all bodily fluids, regardless of patient medical history, should be handled only with gloves [2]. Since then, use of gloves for handling bodily fluids has been the standard of care worldwide.
    In December 2019, an outbreak of a severe respiratory viral illness was recognized in Hubei Province, China with the clinical disease subsequently being labelled as coronavirus disease-2019 (COVID-19) [3]. This virus is highly contagious, spread through droplets with possible aerosol and fomite transmission [4]. The current understanding is that although symptomatic patients are the most contagious, asymptomatic individuals may also transmit the infection [4]. Furthermore, symptoms can be atypical in a significant proportion leading to delayed or missed diagnosis. In a recently published study, 29% of infected individuals were HCP and at least 10 of them were infected by one patient who presented with non-specific gastrointestinal symptoms [5]. In Italy alone, it is estimated that so far at least 6,205 HCP were infected from COVID-19, and 37 physicians died as a consequence of the infection [6]. Furthermore, it is estimated that 12% of the COVID-19 patients were infected due to exposure to an infected HCP or from another hospitalized patient. Accordingly, in addition to the risk for these HCP, which may adversely affect provision of health care, HCP can act as vectors transmitting the disease forward [5].
    Given the highly contagious properties of this virus [4] and lack of universal testing to detect asymptomatic individuals, at minimum, respiratory precautions using facemasks are critical to protect HCP and to prevent further downstream exposure to individuals seeking medical care.
    As in 1987, when the CDC guidelines were changed in an effort to protect HCP from HIV and Hepatitis infections, the ongoing COVID-19 pandemic mandates another update to recommend wearing, at minimum, facemasks for every patient encounter, even for individuals who are not considered at risk for COVID-19 infection.


    1. Ng K, Poon BH, Kiat Puar TH, Shan Quah JL, Loh WJ, Wong YJ, Tan TY, Raghuram J.Ng K, et al. COVID-19 and the Risk to Health Care Workers: A Case Report Ann Intern Med. 2020 Mar 16:L20-0175

    2. Centers for Disease Control. Recommendations for prevention of HIV transmission in health-care settings. MMWR 1987;36(suppl no. 2S).

    3. Zhou F, Yu T, Du R, et al. Clinical course and risk factors for mortality of adult inpatients with COVID-19 in Wuhan, China: a retrospective cohort study. Lancet. 2020.

    4. Transmission of Coronavirus Disease 2019 (COVID-19). Centers for Disease Control and Prevention. https://www.cdc.gov/coronavirus/2019-ncov/prepare/transmission.html. Published March 4, 2020. Accessed March 25, 2020.
    5. Wang D, Hu B, Hu C, et al. Clinical Characteristics of 138 Hospitalized Patients With 2019 Novel Coronavirus-Infected Pneumonia in Wuhan, China. JAMA. 2020;323:1061.

    6. Integrated surveillance of COVID-19 in Italy. https://www.epicentro.iss.it/coronavirus/bollettino/Infografica_25marzo%20ENG.pdf
    Vivian Ip MBChB FRCA 1, Rakesh V. Sondekoppam MBBS MD 2, Timur J.P. Ozelsel MD DESA 1, Ban C.H. Tsui MD MSC FRCPC 331 March 2020
    COVID-19: Protecting healthcare workers is first an d foremost
    To the editor,

    We read with interest the case report describing the favorable outcome (i.e., negative RT-PCR of nasopharyngeal swab) in 41 health care workers (HCW) who were inadvertently exposed to SARS-CoV-2 (COVID-19) after aerosol-generating medical procedures (AGMPs), where only 15% wore N95 masks and 85% surgical masks.[1] We are pleased to know of the wellbeing of all 41 HCW, but would like to highlight several issues which may make generalization of this case difficult. Details as to which HCW donned what level of personal protective equipment (PPE) for which specific type of AGMPs performed is needed to determine if the risk of exposure coincided with the level of PPE. Not all AGMPs have the same risk of infection as seen with the SARS epidemic, with the most consistent association across multiple studies being tracheal intubation.[2] Several factors influence infection to HCW, such as viral shedding by the patient, close-range aerosol transmission as in AGMPs or ventilation/air-flows.[3-4] Further, the possibility of recall bias by the HCW cannot be ruled out. Most importantly, this case should not be misinterpreted as N95 respirators and surgical masks having equal safety value for HCP, or a lack of close-range aerosol transmission,* especially in view of increased risk of COVID infection with lower level of PPE.** Rather it shows that 41 HCP could have been infected by one patient, and the requirement for quarantine.
    What also caught our attention was the seeming lack of heightened awareness for potential COVID-19 infection, when the patient presented in February 2020 with pneumonia amid the epidemic. Admittedly, missing a new disease could have happened anywhere. With COVID-19 a pandemic now, HCW should consider all patients presenting with influenza-like illness to be infected with COVID-19.[5] In other words, there is an urgent need for treating all untested patients as presumed infectious in the presence of increasing community spread.
    HCW need to be extra vigilant in protecting themselves and others from infection. Proper PPE with N95 masks for AGMPs is paramount. While the present shortage of PPE world-wide amid the pandemic may make the use of surgical masks instead of N95 masks attractive, exposing HCW to infection due to potentially inferior PPE may be short-sighted and needs to be avoided. As production of PPE worldwide is increasing, together with sustainable strategies being developed to overcome shortages, HCW must be protected first and foremost to fight the pandemic.
    * Alberta Health Services Response to Media reports about COVID-19 being airborne https://www.albertahealthservices.ca/assets/info/ppih/if-ppih-covid-19-response-airborne.pdf (Accessed 29 Mar 2020)
    ** Spinal anaesthesia for patients with coronavirus disease 2019 and possible transmission rates in anaesthetists: retrospective, single-centre, observational cohort study https://doi.org/10.1016/j.bja.2020.03.007 (Accessed 29 March 2020)
    *** FDA approved reusable respirator

    1. Ng K, Poonn BH, Puar T et al. COVID-19 and the risk to health care workers: a case report. Annal of int med 2020, march 16.
    2. Tran K, Cimon K, Severn M et al. Aerosol generating procedures and risk of transmission of acute respiratory infections to healthcare workers: a systematic review. PLoS One 2012;7(4):e35797.
    3. Cowling BJ, Ip DK, Fan VJ et al. Aerosol transmission is an important mode of influenza A virus spread. Nat Commun 2013;4(4):1935.
    4. Lee N, Hui D, We A et al. A major outbreak of severe acute respiratory syndrome in Hong Kong. N Engl J Med 2003, 15;348:1986-94.
    5. Bogoch II, Watts A, Thomas-Bachli A, Huber C, Kraemer MU, Khan K. Potential for global spread of a novel coronavirus from China. J Travel Med 2020; DOI: https://doi.org/10.1093/jtm/taaa011.
    Jacqueline Sedgwick, MD, MPH20 March 2020
    Prior randomized clinical trial demonstrated N95 superiority -decreased infection transmission including influenza
    Please review: "A randomized clinical trial of three options for N95 respirators and medical masks in health workers", Am J Respir Crit Care Med Vol 187, Iss. 9, pp 960-966, May 1 2013 by C. Raina MacIntyre, Quanyi Wang, et al which found continuous use (not just for procedures, but for all possible exposures) to result in significantly lower rates of clinical respiratory infection in HCWs compared with targeted use or medical (surgical) masks.
    James Siu Ki Lau, Chi Kit Yuen19 March 2020
    Staying vigilant against COVID-19: Awareness and Proper Personal Protective Equipment
    Dear editor,
    We read the published article by Kangqi Ng et al [1] titled "COVID-19 and the Risk to Health Care Workers: A Case Report" with great interest.

    However, we would like to voice some concerns regarding the infection control in severe acute respiratory disease in health care workers which is seemingly substandard in the study.

    Firstly, awareness of the COVID-19 is paramount. In Ng’s case, the surveillance of COVID-19, which should have been done on the first day after admission, was performed only after the patient was mechanically ventilated for 3 days and after extubation.

    The delay in surveillance for COVID-19 also results in delay in contact tracing and isolation of unprotected HCWs (2). By the end of January in the Asia Pacific region, the highly infectious virus with significant morbidity and mortality COVID-19 (novel coronavirus at that time) was already on the news daily. The lack of awareness of the possibility of COVID-19 by the team could have devastating consequences such as spreading the disease into the community by healthcare workers. In addition to not allowing family/friends to visit the hospitals except in very special circumstances, hospitals in Hong Kong have exercised an enhanced surveillance strategy very early on in February to combat the spread of the disease in hospital wards and community. It screens all patients admitted with the diagnosis of pneumonia for COVID-19 in designated isolation wards.

    Secondly, according to guidelines of both CDC and WHO (3), N95 or higher-level respirators should be used during aerosol-generating procedures. A large proportion of the 41 healthcare workers involved in caring the index patient were not in proper personal protective equipment when performing aerosol generating procedures. It is an unacceptable risk to any healthcare worker worldwide. In Tran’s study with WHO (4), they concluded aerosol generating procedures such as tracheal intubation, non-invasive ventilation, tracheotomy, and manual ventilation before intubation were associated with increased risk of SARS transmission to healthcare workers (4). Underlying reason for non-compliance to international guideline for proper application of PPE was not investigated in the study. Inadequate protection during aerosol generating procedures not just affects healthcare workers, but also their family, community, country and the world.

    In conclusion, we agree with Ng that their negative yielding study is limited and we follow what most experts recommend so far on the use of N95 masks when performing aerosol generating procedures. We advocate staying vigilant against COVID-19 and not leaving our health and world to luck.

    1. Ng K, Poon BH, Puar THK et al. COVID-19 and the Risk to Health Care Workers: A Case Report. Annals of Internal Medicine, 2020. doi:10.7326/L20-0175
    2. World Health Organization. Infection prevention and control of epidemic-and pandemic-prone acute respiratory diseases in health care. June 2014. Accessed at https://apps.who.int/iris/bitstream/handle/10665/112656/9789241507134_eng.pdf?sequence=1 on 19 March 2020
    3. World Health Organization. Rational use of personal protective equipment for coronavirus disease 2019 (COVID-19). 27 February 2020. Accessed at https://apps.who.int/iris/bitstream/handle/10665/331215/WHO-2019-nCov-IPCPPE_use-2020.1-eng.pdf on 19 March 2020.
    4. Tran K, Cimon K, Severn M et al. (2012) Aerosol generating procedures and risk of transmission of acute respiratory infections to healthcare workers: A systematic review. PLoS ONE, 7 (4):1-8.
    Jeffery Lee19 March 2020
    Eye shield
    Could you comment on whether the healthcare workers were using eye shields or other eye protection?
    Karolina Akinosoglou, Charalambos Gogos17 March 2020
    Self-isolation of COVID-19-exposed asymptomatic health care workers (HCW): Wise or Worrying ?
    Ng et al describe the clinical outcome of health care workers (HCW) who took care of a patient with COVID-19 pneumonia (1). Following 14-day isolation and serial PCR testing, none of the HCW involved were infected. However, as the pandemic progresses, and the need for increased testing and mitigation of HCW shortages increases, a number of concerns rise reagrding HCW exposure.
    Recent data has shown us that COVID-19 transmission can go undetected, by asymptomatic individuals (2). Exposed HCW could potentially become asymptomatic carriers, and, infect patients and/or colleagues. Hence, self-isolation is crucial to prevent transmission. However, in the case of HCW one should carefully weigh against the reality of the existing struggling health care system, that is required to respond to increased needs and workload. Where the fine line between risk to transmit to inpatient vulnerable groups, and establish the epidemic from “within”, and risk to push the system beyond repairable damage from existing non-sufficient personnel burn out, lies, remains elusive. Either way, the result would be the same, while it has become clear that health care resource availability, including HCW shows a clear association with disease mortality. (3)
    Even if one can afford asymptomatic exposed HCW self-isolation, timing of return to work is an open question, due to delayed virus shedding. Repeated negative testing has been adopted by many settings to optimize return to community, similar to follow up of discharged patients (4). However, in the case of exposed asymptomatic HCW, during the peak of a pandemic crisis, things can become more complex, since the actual risk and clinical impact of transmission via asymptomatic carriers still remains to be clearly quantified by mathematical models (5). Non-isolation and close monitoring via for example every other day screening of asymptomatic - high risk to develop symptoms - HCW could be an option in high income countries, that for example next-generation sequencing technology is available and affordable. Nonetheless, in the growing needs of an evolving epidemic, all settings should be managed as potentially resource-limited and any decision made should well justify its cost-effectiveness. Testing to confirm freedom-of-disease in asymptomatic individuals may come second, in view of the increased needs of diagnosis of symptomatic patients
    The days to come will challenge health care systems to unforeseen limits. Temporary self-isolation of asymptomatic HCW, should be well balanced against unbearable needs, and alternative ways of close monitoring should be explored, to ensure best outcomes