Researchers assess the risks of SARS-CoV-2 surface contamination in a hospital setting

The high incidence and rapid transmission of coronavirus syndrome 2 (SARS-CoV-2) infection has required several tests. Early in the 2019 pandemic of coronavirus infection (COVID-19), caused by SARS-CoV-2 infection, scientists tested everywhere for the risks of live virus contamination – skin, food, water, door handles, surface made of copper, stainless steel, cardboard, and plastic.

However, there is still a lack of data on the survival and infectivity of the surface SARS-CoV-2 in confined environments. Also, the environmental viability of SARS-CoV-2 is not yet understood.

Although qRT-PCR (quantitative reverse transcriptase-polymerase chain reaction) studies have shown that viral RNA has been present for up to several weeks, the lack of viral RNA detected in oncology ward hosts patients with COVID-19. Contradictory perceptions undermine the importance of the presence and infectivity of this virus on the surface of an environment.

In this context, an interdepartmental team from the University of California Davis, USA, analyzed the surface swabs for SARS-CoV-2 RNA and their infectivity in a hospital setting with both qRT-PCR and viral culture assay. They also determined its suitability for order analysis and phylogenetically identified the source of the virus.

The team says this is the first report of an overgrowth of SARS-CoV-2 genome sequences that are virtually direct from environmental surface swabs.

They found little likelihood of SARS-CoV-2 contamination on hospital surfaces with an infectious virus, controversy over the importance of ‘fomites’ in COVID-19 transmission. Also, infectious viruses were not found from the landlords; this is in line with previous studies.

However, the researchers found almost complete genome sequences from two surfaces, suggesting that some viral genomes are present even though they are not infectious. The researchers extended the viral sequences from several samples, which seemed negative with qRT-PCR. Interestingly, this clarifies the ability to obtain viral sequences in some negative PCR samples.

The phylogenetic analysis helped the team identify the source of the advanced SARS-CoV-2 genomes – derived from hospitalized patients. In particular, the environmental contamination was linked to a single line of the virus, possibly from a single patient.

For this study, the team collected the samples during the two waves of COVID-19 at the University of California, Davis Medical Center, in COVID-19 patient and staff conference areas. They collected the first set of samples in April 2020 and the second set between the end of July and the beginning of August 2020.

They examined the advanced qRT-PCR samples in Vero cell cultures for cytopathic effects and then phylogenetically evaluated the samples by whole genome sequencing. The complete protocol used can be found here online.

Even though we found almost complete genome sequences in some, none of the advanced samples (11 of 224 in total) produced cytopathic effects in cultured cells suggested that this nucleic acid was not associated with incomplete virions, or were not present in sufficient numbers for infection. . ”

In this study, the researchers found that improved patient cleaning and management practices between April and August 2020 were associated with less reduction of SARS-CoV-2 RNA from hospital surface samples. Significant reduction of SARS-CoV-2 qRT-PCR imaging (from 11% to 2%) is observed in hospital surface samples.

Improved patient management of respiratory secretion included earlier intubation, rapid series ventilation, and changes in the management of nasal cannulas of high O2 flow.

The researchers identified, in mid-August, 2020, when the second increase of COVID-19 cases was admitted, significantly increasing the number of hospitalized patients.

However, the improved cleaning practices and patient management helped to reduce the environmental presence of the facts.

They also found that the SARS-CoV-2 RNA from the hospital surface did not reveal an infectious nature in the Vero cell culture model in vitro.

The researchers reported that the PCR and whole-genome sequence produce a more efficient detection of SARS-CoV-2 than the qRT-PCR. The genomic sequences separated from negative qRT-PCR samples show improved sensitivity of viral detection by sequencing.

From two different patient rooms (from the floor and top of a dirty net basket), they also obtained two almost complete genomes.

Phylogenetic analysis suggested that the SARS-CoV-2 genomes of the advanced samples were derived from hospitalized patients. The researchers noted that the genome sequences recovered from shoreline were 19B – possibly from a single patient or multiple patients with identical viruses.

In this study, the researchers reported that the 11% of samples collected at UC Davis Medical Center in April 2020 were positive for SARS-CoV-2, but although a larger follow-up test in August found no only 2% of swabs were positive. This is likely due to better cleaning protocols and better management of patients ’respiratory tract. Some viral genomes are present but infectious. This study highlights the potential for viral sequences in some PCR-negative samples.

In the ongoing fight against pandemic, this study sheds light on the importance of protocols and procedures in research studies. Results from the specific observations will help health care workers, and researchers adopt better SOPs.

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