乌鸦传媒

No healthcare workers developed COVID-19 coronavirus infection and there were no hospital-acquired infections at one Hong Kong hospital, with environmental transmission not appearing to be a predominant route of transmission for this virus, researchers found.

Also, no coronavirus was found in air samples taken around the face of one COVID-19 patient with a moderate viral load when the patient was breathing, speaking, or coughing, reported Kwok-Yung Yuen, MD, of the University of Hong Kong, and colleagues.

In fact, virus was detected on only one environmental sample: a window bench in the room, the authors wrote in .

"The descriptive study employed unique environmental and air samples with the results suggesting that environmental transmission may play less of a role than person to person transmission in disease propagation," said Gonzalo Bearman, MD, of Virginia Commonwealth University, in a statement; Bearman reviewed the study, but was not involved in the research.

Yuen and colleagues also outlined a series of enhanced infection control measures by the Hospital Authority in Hong Kong, including "a bundle of early recognition, isolation, notification and molecular diagnostic for all suspected cases."

Even prior to a suspected case being isolated in an airborne infection isolation room, there was active surveillance upon a patient's admission to the hospital, based on a set of clinical and epidemiological criteria. The patient could be cared for in the isolated room or a hospital ward with "1 meter" (a few feet) of space between patients.

Staff education played a key role, including practical training sessions for using personal protective equipment and "enhanced infection control measures" with personal protective equipment clearly illustrated, the authors said.

Most importantly, once a case was identified, infection control teams would follow up with healthcare workers and patients with "unprotected exposure." Close contact with unprotected exposure required 14 days quarantine following last exposure, and 14 days of medical surveillance afterwards, during which time they would be "advised to wear a surgical mask in the hospital and community."

In fact, there were 11 healthcare workers out of 413 who were quarantined for 14 days, and none developed the infection.

Of the 1,275 patients fulfilling clinical and epidemiological criteria for COVID-19, 42 tested positive. Cases were a median age of 59, with about a 50/50 split between the sexes. Thirty-three patients were Hong Kong residents. There were 27 locally acquired cases of the virus. One patient died and four remained in critical condition at the end of the study.

A study in published Wednesday also examined environmental samples, including air samples, from three patients in airborne isolation rooms in Singapore and found similar results in terms of air sampling.

However, the researchers found "swabs taken from the air exhaust outlets tested positive, suggesting that small virus-laden droplets may be displaced by airflows and deposited on equipment such as vents." Personal protective equipment tested negative except for the surface of a shoe front.

Samples taken from one patient's room prior to routine cleaning were positive on 13 of 15 room sites, including air outlet fans and three of five toilet sites including toilet bowl, sink, and door handle. Researchers noted that this patient had "upper respiratory tract involvement with no pneumonia and 2 positive stool samples ... despite not having diarrhea."

"Viral shedding in stool could be a potential route of transmission," the authors said, noting that this patient had greater viral shedding than the other two patients.

However, all post-cleaning samples tested negative, "suggesting that current decontamination measures are sufficient," the researchers wrote. They added that contamination through "respiratory droplets and fecal shedding" supports the need for strict adherence to environmental and hand hygiene procedures.

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