Air dispersal of severe acute respiratory coronavirus virus 2 (SARS-CoV-2): Implications for hospital infection control during the fifth wave of coronavirus disease 2019 (COVID-19) due to the SARS-CoV-2 omicron variant in Hong Kong

Antimicrobial Resistance Situation and Control Measures in Hong Kong: From a One Health Perspective

Multidrug-resistant organisms pose a critical public health challenge globally, particularly in densely populated Hong Kong with a rapidly aging population, where over 90% of food is imported. This review examines the targeted surveillance and control efforts implemented under the One Health framework to combat antimicrobial resistance (AMR). Between 2010 and 2023, surveillance revealed a prevalence of extended-spectrum-beta-lactamase-producing Escherichia coli (ESBL-E.coli) in tested pigs (51.5%) and chickens (86.3%). Alarmingly, carbapenemase-producing E. coli was increasingly detected in pigs (<5 to 19.2% from 2017 to 2023). For other food items, ESBL-producing Enterobacterales were found in sashimi (11.5%), sushi (4.8%) ready-to-eat (RTE) vegetables (26.9%), RTE cut fruits (5.6%), braised dishes (19.8%), and roast meat (2.4%). Mean antimicrobial consumption in food animals was 113.4mg/kg target animal biomass for pigs from 2019 to 2022. Antimicrobial consumption in hospitals and community, expressed as defined daily doses per 1,000 inhabitants per day, declined from 20.4 to 13.8 during the COVID-19 pandemic, and gradually rebounded to 17.1 in 2023. In residential care homes for the elderly (RCHE), MRSA prevalence rapidly escalated from 2.8 to 48.7% between 2005 and 2021, triggering a pilot MRSA decolonization program in 257 RCHEs, which led to a significant reduction in community-onset MRSA infections (from 3.526 to 2.632 per 1,000-resident-days,p<0.005) and MRSA bacteremia (from 0.322 to 0.197 per 1,000-resident-days,p=0.025). These findings highlight the challenges in the control of ESBL and carbapenemase-producing E. coli in animals, compliance with food hygiene measures, and infection control in overcrowded and understaffed RCHE or hospitals in perpetuating MRSA infections in healthcare settings.

Tracking SARS-CoV-2 RNA in the air: Lessons from a COVID-19 outbreak in an infirmary unit

BACKGROUND

The duration and magnitude of SARS-CoV-2 air dispersal during nosocomial outbreaks remain uncertain. This study evaluates the impact of mobile modular high-efficiency particulate air filter units (MMHUs) on SARS-CoV-2 air dispersal.

METHODS

We investigated a nosocomial COVID-19 outbreak in an infirmary unit. The viral load (VL) of SARS-CoV-2 in air samples was correlated with the VL in nasopharyngeal swabs with or without MMHU. These samples underwent whole-genome sequencing and phylogenetic analysis.

RESULTS

Upon outbreak declaration (August 2, 2024, day 0), 44 (69.8%) of 63 patients acquired COVID-19 in Ward 2B (19 male) and 2C (25 female) by day 4. The VL of SARS-CoV-2 remained detectable in air until day 11 (2B) and day 20 (2C). The VL of air samples was significantly correlated with the VL in nasopharyngeal swabs collected on days 5, 7, 10, and 13 in 2C (r = -0.975, P = .004). Using MMHU, the mean daily ratio of SARS-CoV-2 RNA (copies/1,000 L of air/patient) in 2B was 5 times lower than in 2C from days 5 to 10. Whole-genome sequencing revealed all 41 tested strains belonged to the Omicron variant, KP.3.1.1, phylogenetically related to the prevailing community strains.

CONCLUSIONS

Using MMHU mitigates the duration and magnitude of SARS-CoV-2 air dispersal during nosocomial outbreak.

The Emergence of Candida auris is Not Associated with Changes in Antifungal Prescription at Hospitals

Purpose

This study describes the emergence of Candida auris in Hong Kong, focusing on the incidence and trends of different Candida species over time. Additionally, the study analyzes the relationship between C. auris and antifungal prescription, as well as the impact of outbreaks caused by C. auris.

Patients and Methods

Data were collected from 43 public hospitals across seven healthcare networks (A to G) in Hong Kong, including Candida species culture and antifungal prescription information. Among 150,267 patients with 206,405 hospitalization episodes, 371,653 specimens tested positive for Candida species. Trends in Candida species and antifungal prescription were analyzed before (period 1: 2015 1Q to 2019 1Q) and after (period 2: 2019 2Q to 2023 2Q) the emergence of C. auris in Hong Kong.

Results

Candida albicans was the most prevalent species, accounting for 57.1% (212,163/371,653) of isolations, followed by Candida glabrata (13.1%, 48,666), Candida tropicalis (9.2%, 34,261), and Candida parapsilosis (5.3%, 19,688). C. auris represented 2.0% of all Candida species isolations. Comparing period 2 to period 1, the trend of C. albicans remained stable, while C. glabrata, C. tropicalis, and C. parapsilosis demonstrated a slower increasing trend in period 2 than in period 1. Other species, including C. auris, exhibited a 1.1% faster increase in trend during period 2 compared to period 1. Network A, with the highest antifungal prescription, did not experience any outbreaks, while networks F and G had 40 hospital outbreaks due to C. auris in period 2. Throughout the study period, healthcare networks B to G had significantly lower antifungal prescription compared to network A, ranging from 54% to 78% less than that of network A.

Conclusion

There is no evidence showing correlation between the emergence of C. auris and antifungal prescription in Hong Kong. Proactive infection control measures should be implemented to prevent nosocomial transmission and outbreak of C. auris.

Investigation of air dispersal during a rhinovirus outbreak in a pediatric intensive care unit

BACKGROUND

While airborne transmission of rhinovirus is recognized in indoor settings, its role in hospital transmission remains unclear.

METHODS

We investigated an outbreak of rhinovirus in a pediatric intensive care unit (PICU) to assess air dispersal. We collected clinical, environmental, and air samples, and staff's surgical masks for viral load and phylogenetic analysis. Hand hygiene compliance and the number of air changes per hour in the PICU were measured. A case-control analysis was performed to identify nosocomial rhinovirus risk factors.

RESULTS

Between March 31, 2023, and April 2, 2023, three patients acquired rhinovirus in a cubicle (air changes per hour: 14) of 12-bed PICU. A portable air-cleaning unit was placed promptly. Air samples (72,000 L in 6 hours) from the cohort area, and outer surfaces of staff's masks (n = 8), were rhinovirus RNA-negative. Hand hygiene compliance showed no significant differences (31/34, 91.2% vs 33/37, 89.2%, P = 1) before and during outbreak. Only 1 environmental sample (3.8%) was positive (1.86 × 103 copies/mL). Case-control and next-generation sequencing analysis implicated an infected staff member as the source.

CONCLUSIONS

Our findings suggest that air dispersal of rhinovirus was not documented in the well-ventilated PICU during the outbreak. Further research is needed to better understand the dynamics of rhinovirus transmission in health care settings.

Epidemiology of COVID-19 in Infants in the United States: Incidence, Severity, Fatality, and Variants of Concern

BACKGROUND

The clinical spectrum of infant COVID-19 ranges from asymptomatic infection to life-threatening illness, yet epidemiologic surveillance has been limited for infants.

METHODS

Using COVID-19 case data (restricted to reporting states) and national mortality data, we calculated incidence, hospitalization, mortality and case fatality rates through March 2022.

RESULTS

Reported incidence of COVID-19 was 64.1 new cases per 1000 infant years (95% CI: 63.3-64.9). We estimated that 594,012 infants tested positive for COVID-19 nationwide by March 31, 2022. Viral variant comparisons revealed that incidence was 7× higher during the Omicron (January-March 2022) versus the pre-Delta period (June 2020-May 2021). The cumulative case hospitalization rate was 4.1% (95% CI: 4.0%-4.3%). For every 74 hospitalized infants, one infant death occurred, but overall COVID-19-related infant case fatality was low, with 7.0 deaths per 10,000 cases (95% CI: 5.6-8.7). Nationwide, 333 COVID-19 infant deaths were reported. Only 13 infant deaths (3.9%) were the result of usually lethal congenital anomalies. The majority of infant decedents were non-White (28.2% Black, 26.1% Hispanic, 8.1% Asian, Indigenous or multiracial).

CONCLUSIONS

More than half a million US infants contracted COVID-19 by March 2022. Longitudinal assessment of long-term infant SARS-CoV-2 infection sequelae remains a critical research gap. Extremely low infant vaccination rates (<5%), waning adult immunity and continued viral exposure risks suggest that infant COVID-19 will remain a persistent public health problem. Our study underscores the need to increase vaccination rates for mothers and infants, decrease viral exposure risks and improve health equity.

Infection of healthcare workers despite a high vaccination rate during the fifth wave of COVID-19 due to Omicron variant in Hong Kong

Background

No nosocomial infection was recorded in our healthcare workers (HCWs) during the early phase of the coronavirus disease 2019 (COVID-19) pandemic. With the emergence of the Omicron variant of increased transmissibility, infection in HCWs occurred as expected. We aimed to study the epidemiology of infection in HCWs and to describe the infection control measures during the outbreak of the Omicron variant.

Methods

With daily rapid antigen testing and molecular confirmation test for COVID-19, infected HCWs were interviewed by infection control nurses (ICNs) to investigate the potential source of infection. The epidemiology of COVID-19 in Hong Kong served as reference.

Results

During the fifth wave of COVID-19 (31 December 2021 to 31 May 2022), 1,200,068 cases were reported (incidence 95 times higher than in preceding waves in Hong Kong; 162,103 vs 1,707 per million population respectively, P<0.001). The proportion of infected HCWs was significantly higher than that of the general population (24.9%, 1,607/6,452 vs 16.2%, 1,200,068/7,403,100 respectively; P<0.01). The proportion of infected non-clinical staff was significantly higher than that of clinical staff (31.8%, 536/1,687 vs 22.5%, 1,071/4,765 respectively; P<0.001). Of 82.8% (1,330/1,607) infected HCWs interviewed by ICNs, 99.5% (1,324/1,330) had been fully vaccinated; 49.5% (659/1,330) had no identifiable source; 40.7% (541/1,330) were probably infected from household members; 9.8% (130/1,330) had possible exposure to confirmed patients or HCWs, but no lapse in infection control measures or inappropriate use of personal protective equipment was recalled.

Conclusion

Omicron variant is highly transmissible such that breakthrough infection occurred despite high level of vaccination.