key: cord-270909-wb7mwklo
authors: Cheng, Vincent C.C.; Wong, Shuk-Ching; Chuang, Vivien W.M.; So, Simon Y.C.; Chen, Jonathan H.K.; Sridhar, Siddharth; To, Kelvin K.W.; Chan, Jasper F.W.; Hung, Ivan F.N.; Ho, Pak-Leung; Yuen, Kwok-Yung
title: Absence of nosocomial transmission of coronavirus disease 2019 (COVID-19) due to SARS-CoV-2 in the pre-pandemic phase in Hong Kong
date: 2020-05-24
journal: Am J Infect Control
DOI: 10.1016/j.ajic.2020.05.018
sha: 
doc_id: 270909
cord_uid: wb7mwklo

BACKGROUND: To describe the infection control strategy to achieve zero nosocomial transmission of symptomatic coronavirus disease (COVID-19) due to SARS-CoV-2 during the pre-pandemic phase (the first 72 days after announcement of pneumonia cases in Wuhan) in Hong Kong. METHODS: Administrative support with the aim of zero nosocomial transmission by reducing elective clinical services, decanting wards, mobilizing isolation facilities, providing adequate personal protective equipment, coordinating laboratory network for rapid molecular diagnosis under 4-tier active surveillance for hospitalized- and out-patients, and organizing staff forum and training was implemented under the framework of preparedness plan in Hospital Authority. The trend of SARS-CoV-2 in the first 72 days was compared with that of SARS-CoV 2003. RESULTS: Up to day 72 of the epidemic, 130 (0.40%) of 32,443 patients being screened confirmed to have SARS-CoV-2 by RT-PCR. Compared with SARS outbreak in 2003, the SARS-CoV-2 case load constituted 8.9% (130 SARS-CoV-2/1458 SARS-CoV) of SARS-CoV infected cases at day 72 of the outbreak. The incidences of nosocomial acquisition of SARS-CoV per-1,000-SARS-patient-day and per-100-SARS-patient-admission were 7.9 and 16.9 respectively, which were significantly higher than the corresponding incidences of SARS-CoV-2 (zero infection, p<0.001). CONCLUSION: Administrative support to infection control could minimize the risk of nosocomial transmission of SARS-CoV-2.

Pandemic infection of a coronavirus disease 2019 (COVID-19) due to severe acute respiratory syndrome-associated coronavirus-2 (SARS-CoV-2) was declared by World Health Organization (WHO) on 11 March 2020, which is 72 days after announcement of a cluster of patients with community acquired pneumonia in Wuhan, Hubei Province by National Health Commission of the People's Republic of China (NHCPRC), on 31 December 2019 (day 1) [1] . On day 72, the COVID-19 had already spread to 113 countries or territories in five continents, resulting in 118,319 confirmed cases all over the world [2] . While the epidemic of COVID-19 is slowing down in China, there is active community transmission in Europe and North America, resulting in 30% of disease burden is outside China [2] . Overwhelming number of COVID-19 infections could not only paralyze the healthcare system, but more importantly, result in nosocomial outbreak, associated with increased morbidity and mortality of the hospitalized patients and healthcare workers (HCWs). Up to 24

February 2020 (day 56), NHCPRC reported that 3,387 healthcare workers were infected with COVID-19, resulting in 22 (0.6%) deaths [3] . This has exceeded the number of HCWs death due SARS in mainland China after 6 months in 2003 [4] . In Hong Kong, eight HCWs succumbed as a result of nosocomial acquisition of SARS-CoV [5] . The top priority of our pandemic preparedness is to achieve zero COVID-19 infection among HCWs in Hong Kong.

Here, we report our infection control strategy and epidemiology of SARS-CoV-2 in the first 72 days (from the official announcement of pneumonia by NHCPRC to the declaration of pandemic infection by WHO), using the historical data on the epidemiology of SARS-CoV in Hong Kong for comparison.

After the outbreak of SARS-CoV in 2003, a total of 1755 persons were infected and 299 persons (17.0%) died [6] . Of 386 healthcare workers (HCWs) infected with SARS-CoV in Hong Kong, 8 of them (2.2%) succumbed. Six HCWs (2 doctors, 1 nurse, and 3 healthcare assistants) of 8 were the employee of Hospital Authority, the governing body of all 43 public hospitals, divided into 7 cluster-networks, responsible for 90% of inpatient service in Hong Kong. A "Select Committee to inquire into the handling of the Severe Acute Respiratory Syndrome outbreak by the Government and the Hospital Authority" was established by the Legislative Council of the Hong Kong Special Administrative Region, China to in order to examine the performance and accountability of the Government and Hospital Authority and their officers at policymaking and management levels [7] . The report includes temporal sequence of events and daily statistics on SARS patients with breakdown by healthcare workers and patients. The information is retrieved for analyzing the epidemiology of SARS in 2003 [8] . When a novel coronavirus disease, known as COVID-19 due to SARS-CoV-2 emerged 17 years later, Hospital Authority immediately activated our response plan to combat the epidemic and to prevent nosocomial transmission and outbreaks of SARS-CoV-2. The clinical perspective of infection control measures was reported recently [9] . The epidemiology of SARS-CoV-2 until 11 March 2020 (at day 72 after the official announcement of a cluster of pneumonia of unknown etiology in Wuhan, Hubei Province, by NHCPRC in Hong Kong) was analyzed. This is also the date when WHO declared the COVID-19 pandemic. Our results were compared with the epidemiological data of SARS-CoV at day 72 (11 April 2003) after the official announcement of atypical pneumonia in Guangdong Province, China on 11 February 2003. In addition, we also compared the epidemiology of SARS-CoV-2 in Hong Kong with Hubei Province, China, which is the most severe affected region by SARS-CoV-2, and the other countries or areas with uncontrolled local transmission at day 72, including Republic of Korea, Islamic Republic of Iran, and Italy, using the publicly accessible information from the WHO website [10] .

After the SARS outbreak in 2003, a preparedness plan for emerging infectious diseases, including pandemic influenza and Middle East Respiratory Syndrome-associated coronavirus, was formulated under the governance of Hospital Authority.

The preparedness plan to combat against SARS-CoV-2 is basically referring to the framework of these plans. According to the risk assessment, the response levels can be categorized into alert level, serious response level 1 (S1), serious response level 2 (S2), and emergency response level [11] . The command structure depends on the different response levels ( Figure 1 ). In the alert and S1 level, the response plan is coordinated by ad hoc Central Committee on Infectious Disease and Emergency Responses (ad hoc CCIDER). In the S2 and emergency response level, the governance will be under the command of Central Command Committee, which is chaired by Chief Executive of Hospital Authority, or Emergency Executive Committee, which is chaired by Chairman of Hospital Authority. The response measures at each response level comprises of a series of action, including active surveillance and electronic notification, laboratory network for rapid molecular diagnostic, infection control measures, provision of essential medical services, facility management in the hospital, human resources and staff deployment, staff training, research, and communication. Contact tracing for potential secondary cases was performed to investigate for any possible nosocomial infection as reported previously [12, 13] .

Clinical specimens including nasopharyngeal aspirates, nasopharyngeal swabs, throat swab, saliva, sputum, endotracheal aspirates, or bronchoalveolar lavage were subjected to nucleic acid extraction by the eMAG extraction system (bioMérieux, Marcy-l'Étoile France) as previously described [9, 11] . The presence of the SARS-CoV-2 RNA in the specimens was first determined by the LightMix Modular SebeccoV E-gene commercial kit (TIB Molbiol, Berlin, Germany) and further confirmed by another in-house real-time RT-PCR assay targeting the SARS-CoV-2 RNA-dependent RNA polymerase/helicase gene [14] .

The Fisher's exact test was used to compare independent categorical variables between groups. All reported p values were two-sided. A p value of <0.05 was considered statistically significant. Computation was performed using the SPSS Version 15.0 for Windows.

Up to 11 March 2020 (day 72 after the official announcement of a cluster of pneumonia of unknown etiology in Wuhan, Hubei Province, a total of 130 cases of SARS-CoV-2 infection were confirmed in Hong Kong, while the first 42 patients were reported previously [9] . With these additional cases, there were 63 males and 67 HCWs were infected with SARS. 293 (75.9%) of them were investigated for nosocomial acquisition of SARS-CoV in 8 acute hospitals [15] . The incidences of nosocomial acquisition of SARS-CoV per 1,000 SARS-patient-day and per 100 SARS-patient-admission were 7.9 and 16.9 respectively, which were significantly higher than the corresponding incidences of nosocomial acquisition of SARS-CoV-2 (p<0.001).

In the first 72 days, the incidence of SARS-CoV-2 in Hong Kong was 0.16 per 10,000 populations, which was lower than China (Hubei province), Europe (Italy), Asia (Republic of Korea, and Singapore), and Middle East (Iran) ( Table 1) .

Upon receiving the official announcement of a cluster of pneumonia of unknown etiology in Wuhan, Hubei Province, on 31 December 2020 (day 1), the infection control responses were stepped up by Hospital Authority according to the rapidly evolving epidemiology in Hong Kong [9] . The level of response towards emerging infectious disease was directly elevated from alert to S2 on day 5. Ad hoc CCIDER was regularly held among infection control professionals in 7 clusternetworks and senior management team in the head office of Hospital Authority 

Infection of healthcare workers due to occupational exposure to infectious diseases is always a great challenge to hospital administration and infection control professionals. Sporadic cases of occupation related infection among HCWs due to various infectious diseases such as Mycobacterium tuberculosis, hepatitis B virus, and hepatitis C virus were occasionally reported [16] . However, the impact of SARS transmission among HCWs was unprecedentedly high. According to WHO, HCWs accounted for 1,707 (21%) of 8,098 cases of SARS patients in 2003 [6] . It produced a significant psychosocial effects and long-term psychological effects on HCWs [17] .

Therefore, when the COVD-19 emerged, it is important to maximize our administrative resources and infection control measures to protect our HCWs, which is particularly relevant in Hong Kong as we had 8 HCWs died in 2003 as a result of nosocomial acquisition of SARS-CoV [5, 18] .

Administrative support to infection control is important to prevent nosocomial outbreak but it is not well studied in recent years [19] . However, suboptimal administrative support was attributed to the prolonged outbreak of carbapenemaseproducing Enterobacteriaceae in a tertiary care hospital in France [20] , as well as the major outbreak of SARS in Hong Kong [7] . Therefore, the command structure for serially updated along with the evolving epidemic of COVID-19 [9] .

With the support of hospital administration, the infrastructure of hospitals was improved from the period of SARS-CoV to SARS-CoV-2 by the provision of 1400 AIIRs in Hong Kong. Early isolation of patients with SARS-CoV and their close contacts was found to be effective in termination of chain of transmission [5, 18] when the viral load SARS was peaked at day 10 after symptoms onset [5] . For SARS-CoV-2, high viral load was detected soon after onset of symptoms onset [21] . a The evolving criteria of active surveillance was reported [9] . b AAMI level 1 isolation gown is used when small amounts of fluid exposure is anticipated. AAMI level 3 isolation gown can be considered when splashing is anticipated. Alternatively, a waterproof apron on top of the AAMI level 1 isolation gown is also acceptable (with effect from 19 February 2020, day 51) c The fourth tier enhanced laboratory surveillance was updated since 20 February 2020 (day 52). 

The Centre for Health Protection closely monitors cluster of pneumonia cases on Mainland. Press release of the Department of Health

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All authors report no conflicts of interest relevant to this article. 
