A study published in the journal nature has given further supportive evidence that SARS-CoV2, the virus that causes covid-19, can be transmitted by air or through surfaces. The study revealed environmental contamination of surface and air samples with the virus in places where covid-19 positive patients were isolated.
University of Nebraska Medical Center conducted the study in association with National Strategic Research Institute USA. During the initial isolation of 13 individuals with Covid-19 at the University of Nebraska Medical Center, the researchers collected air and surface samples to examine viral shedding from isolated individuals.
The researchers said they detected viral contamination among all samples, supporting the use of airborne isolation precautions when caring for covid-19 patients.
The study has highlighted that as the pandemic progressed, a continued paucity of evidence on routes of SARS-CoV-2 transmission has resulted in shifting infection prevention and control guidelines between classically-defined airborne and droplet precautions.
Patients requiring hospital care were managed in the Nebraska Biocontainment Unit (NBU), and mildly ill individuals were isolated in the National Quarantine Unit (NQU), both located on the medical center campus.
During the study, high-touch personal items sampled included cellular phones, exercise equipment, television remotes, and medical equipment. Room surfaces tested included ventilation grates, tabletops, and window ledges. Toilet samples were obtained from the rim of the bowl. Air samples were collected both in isolation rooms and in the hallways of the NBU and NQU during sampling activities, while patients were present.
For rooms in the Nebraska Biocontainment Unit, samples were taken on the windowsill, the bed rail or bedside table, under the patient’s bed and on the air-conditioning return grate nearest the door.
During the study, surface and aerosol samples were analyzed by RT-PCR targeting the E gene of SARS-CoV-2. Of the 163 samples collected in this study, 121 (72.4%) had a positive PCR result for SARS-CoV-2, according to the findings.
“We found 63.2% of in-room air samples to be positive by RT-PCR. Samples taken outside the rooms in the hallways were 58.3% positive,” the researchers said in the study.
According to the study, 77.8% of samples of cellular phones were found positive for SARS-CoV-2 and 55.6% of remote controls of in-room televisions were positive. Also, samples collected from toilets in isolation rooms were 81% positive. Further, 70.8% of the bedside tables and bed rails indicated the presence of viral RNA. Of all room surfaces sampled, the study said, 75% were positive for SARS-CoV-2 RNA.
The study suggested that patients with higher acuity of illness or levels of care may be associated with increased levels of environmental contamination.
“The data suggests that viral aerosol particles are produced by individuals that have the covid-19 disease, even in the absence of cough,” the study said.
“Our study suggests that SARS-CoV-2 environmental contamination around covid-19 patients is extensive, and hospital IPC procedures should account for the risk of fomite (objects or materials which are likely to carry infection), and potentially airborne, transmission of the virus,” it added.
Despite widespread environmental contamination and limited SARS-CoV-2 aerosol contamination associated with hospitalized and mildly ill individuals, the study said, the implementation of a standard suite of infection prevention and control procedures prevented any documented cases of covid-19 in healthcare workers, who self-monitored for 14 days after last contact with either ward and underwent two nasal swab PCR assays 24 hours apart if they reported fever or any respiratory infection symptoms.
Further study is necessary to fully quantify risk, it added.