Detection and temporal monitoring of SARS-CoV-2 in Norwegian hospitals and other high transmission risk environments (NorCoV2)

The extremely rapid spread of COVID-19 has resulted in a severe global impact. To stem the tide of the current pandemic, understanding how COVID-19 spreads within populations is of paramount importance. One way to reduce transmission is to reduce exposure, which requires knowledge about the exposure risk in different environments and scenarios. Risk of transmission to health personnel must also be addressed, given the importance of a well-functioning health service for dealing with the pandemic. The NorCoV2 project has collected environmental samples in hospital-, subway- and airport environments, which are all important with regard to spreading infectious diseases. Air and surface samples were collected weekly/every other week from the start of the outbreak in Norway to the end of 2020. A total of 434 surface, and 135 air samples were collected in public spaces. SARS-CoV-2 was found in surface samples collected at subway stations and in subway cars. In collaboration with Oslo University Hospital, air surrounding admitted patients was sampled. An experiment that evaluated the effect of nebulizer treatment on the viral load in patient room air revealed that the treatment correlated with a higher viral load, and that this increase coincided with an increase in smaller air particles. This finding may indicate that viral particles were transported in aerosol particles. Only a small number of air samples near patients with very severe symptoms were positive. Furthermore, we observed SARS-CoV-2 in air surrounding non-admitted, COVID-positive persons?with mild symptoms. Virus cultivation was performed on all PCR-positive samples, but none were positive. The results from NorCoV2 showed no environmental contamination in airports, but some in subways and subway cars. Importantly, these results are based on only a few samples (434 surface; 135 air), and a lack of SARS-CoV-2 in environmental samples is not to be taken as evidence of low risk; direct transmission among people?the most important transmission pathway?is not detectable in the utilized sampling methodology. Results from NorCoV2 indicate that there is potentially higher risk for health personnel when patients are given nebulizer treatment, and that the amount of virus in air is likely dependent on disease severity. Lastly, NorCoV2 has demonstrated that COVID-19 infected individuals that have mild symptoms?i.e., not hospitalized and are thus potential sources of viral spreading?indeed have detectable levels of SARS-CoV-2 in the air surrounding them. Project members include important stakeholders from the hospital and mass transit sector. NorCoV2 has contributed data to a large international SARS-CoV-2 mapping effort coordinated by the MetaSUB Consortium.

Outcomes: 1. The project identified SARS-CoV-2 in the subway environment, but not at Oslo Airport. 2. Surface swabbing was identified as a useful monitoring strategy in public areas. 3. Air sampling in a controlled setting revealed that SARS-CoV-2 is detectable in air up to ~4 meters away from subjects showing mild symptoms. 4. Experimental work indicated that nebulizer treatment is associated with higher viral loads in patient room air, which may entail higher risk for healthcare workers. Impact: The utilized methodologies has proven useful with regard to environmental monitoring and risk assessment, showing its utility in current and future pandemics. While no air samples from public spaces were positive, controlled tests, using infected individuals and admitted COVID-19 patients, has improved our understanding of the methodology's sensitivity. Importantly, a potential risk-driver for healthcare workers was identified, namely nebulizer treatment.

The extremely rapid spread of COVID-19 has resulted in a severe global impact. To stem the tide of the current pandemic, reducing transmission rates within populations and understanding the epidemiological dynamics of COVID-19 is of paramount importance. One way to reduce transmission is to reduce exposure, which requires knowledge about the exposure risk in different environments and scenarios. Further, identifying the sources of observed SARS-CoV-2 strains could identify important transmission routes. The NorCoV2 project will utilize environmental sampling in hospital, subway and airport environments, which are all important with regard to spreading infectious diseases. Air and surface samples will be collected weekly for a period of six months. The presence and abundance of SARS-CoV-2 will be analyzed with Real-Time Quantitative Reverse Transcription PCR (qRT-PCR), and samples where SARS-CoV-2 is detected will be direct RNA long-read sequenced on the Oxford Nanopore Technologies (ONT) MinION platform. The results from NorCoV2 will provide information on exposure risk in important infrastructures, examine the effectiveness of cleaning procedures and infection control measures, provide a high-resolution time series analysis of the current outbreak, and perform critical geographic tracking analyses of environmentally observed SARS-CoV-2 strains. Project members include important stakeholders from the hospital and mass transit sector. NorCoV2 will contribute to a large international SARS-CoV-2 mapping effort coordinated by the MetaSUB Consortium.