In German hospitals, the burden is increasing due to the increasing number of Covid 19 patients. In addition to the work pressure, the medical staff has to worry about infecting themselves. This fear also discourages patients with other illnesses from visiting the clinic. French scientists now report in the journal “Jama Network Open” that air samples from intensive care units, corridors and toilets can be contaminated. However, the particles of the SARS-CoV-2 pathogen are usually not viable.
At the end of 2019, a new disease began to spread in China, the lung disease COVID-19 caused by the novel coronavirus SARS-CoV-2. Quarantine measures to contain the virus lead to production losses and increasingly severe consequences for the economy and everyday life.
Studies evaluated in meta-analysis
The team led by pharmacologist Gabriel Birgand from Nantes University Hospital evaluated 24 studies for the meta-analysis, four of which were unpublished. One paper from Great Britain and one from Italy are the only studies from Europe. Ten studies come from China.
The respective teams had taken an average of 24 samples from the air from different hospital areas and analyzed them for viral load using PCR methods. In those areas frequented by patients, a good sixth sample was positive – 82 out of 471 (17.4 percent).
Corridors and toilets polluted
More than 25 percent of the samples in intensive care units were contaminated, compared to just under 11 percent in other wards. The highest percentage of positive samples came from publicly accessible corridors (56 percent) – but only 16 samples were taken there. In general, every third test (33.3 percent) from public clinical areas was positive.
Toilets and bathrooms with a positive rate of almost 24 percent – 5 out of 21 samples – turned out to be additional risk locations. The authors suspect that this is probably due to the fact that these rooms are small and poorly ventilated. Studies had previously shown that the stools of Covid 19 patients contain traces of SARS-CoV-2 and that flushing a toilet can stir up virus-contaminated aerosol clouds.
Risk of transmission in staff rooms
A good twelve percent of the samples in the staff rooms were positive, and a good 19 percent in conference rooms. This goes with a possible transmission of SARS-CoV-2 among employees during breaks, the authors write: During this time, the protective masks in the often small rooms are often removed.
Petra Gastmeier, Director of the Institute for Hygiene and Environmental Medicine at the Berlin Charité, reported at the National Quality Congress on Health at the end of November that a large part of the SARS-CoV-2 transmissions took place in the hospital among employees.
Virus residues are not always infectious
The authors of the meta-analysis admit that the direct comparison of the studies is problematic because the respective teams had very different methodological approaches. They also emphasize that it is mostly unclear whether the virus residues in the positive samples were infectious or not. Virus cultures were only created in five studies; cultivation was only successful in 7 of a total of 81 attempts (8.6 percent).
Further investigations are necessary here. Nonetheless, the high viral loads in toilets, bathrooms, staff areas and hallways meant “that these areas should be carefully considered to prevent Covid-19 transmission”.