Escalating infection control response to the rapidly evolving epidemiology of the coronavirus disease 2019 (COVID-19) due to SARS-CoV-2 in Hong Kong

Abstract

Objective: To describe the infection control preparedness measures undertaken for coronavirus disease (COVID-19) due to SARS-CoV-2 (previously known as 2019 novel coronavirus) in the first 42 days after announcement of a cluster of pneumonia in China, on December 31, 2019 (day 1) in Hong Kong.

Methods: A bundled approach of active and enhanced laboratory surveillance, early airborne infection isolation, rapid molecular diagnostic testing, and contact tracing for healthcare workers (HCWs) with unprotected exposure in the hospitals was implemented. Epidemiological characteristics of confirmed cases, environmental samples, and air samples were collected and analyzed.

Results: From day 1 to day 42, 42 of 1,275 patients (3.3%) fulfilling active (n = 29) and enhanced laboratory surveillance (n = 13) were confirmed to have the SARS-CoV-2 infection. The number of locally acquired case significantly increased from 1 of 13 confirmed cases (7.7%, day 22 to day 32) to 27 of 29 confirmed cases (93.1%, day 33 to day 42; P < .001). Among them, 28 patients (66.6%) came from 8 family clusters. Of 413 HCWs caring for these confirmed cases, 11 (2.7%) had unprotected exposure requiring quarantine for 14 days. None of these was infected, and nosocomial transmission of SARS-CoV-2 was not observed. Environmental surveillance was performed in the room of a patient with viral load of 3.3 × 106 copies/mL (pooled nasopharyngeal and throat swabs) and 5.9 × 106 copies/mL (saliva), respectively. SARS-CoV-2 was identified in 1 of 13 environmental samples (7.7%) but not in 8 air samples collected at a distance of 10 cm from the patient's chin with or without wearing a surgical mask.

Conclusion: Appropriate hospital infection control measures was able to prevent nosocomial transmission of SARS-CoV-2.

Fig. 1.

Active and enhanced laboratory surveillance for diagnosis of SARS-CoV-2 in Hong Kong. Both calendar date and day after official announcement of a cluster of pneumonia in Wuhan, Hubei Province, by the PRC National Health Commission on December 31, 2019, are shown. From day 1 to day 20, pan-coronavirus PCR with modification to detect 23 coronaviruses known to be present in human, animals, and bats was used. From day 21 onward, real-time PCR targeting the E gene of the SARS-CoV-2/SARS-like coronavirus was performed using the LightMix Modular SARS and Wuhan CoV E-gene mix (TIB Molbiol, Berlin, Germany) and the LightCycler Multiplex RNA Virus Master Kit (Roche Diagnostics, Mannheim, Germany).