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

With its rapid spread and significant mortality, COVID-19 poses an enormous challenge to global public health and societal security. A central component in the work to limit the outbreak is to limit the rate of spread within populations. This requires a deep understanding of exposure risk in different environments and different situations. Risks to healthcare workers must also be addressed, given the importance of a well-functioning healthcare system in a pandemic. The NorCov2 project has collected environmental samples from hospitals, metro stations and an airport; three environments that are very important for the spread of infection. Both air and surface samples have been collected regularly (every/every two weeks depending on infection pressure) at airports and subway stations from the start of the outbreak in Norway until the end of 2020. A total of 434 surface and 135 air samples have been collected from public room. SARS-CoV-2 virus was detected in surface samples collected at subway stations and inside subway cars. Testing of SARS-CoV-2 in the air around hospitalized patients and infected persons with less severe symptoms is carried out in collaboration with Oslo University Hospital. An experiment evaluating the effect of treatment with a nebulizer on the amount of virus in air showed that the amount of virus was higher during treatment compared to control, and that this increase coincided with an increase in smaller particle sizes which can be taken as an indication of the transport of virus in aerosol particles. Only a small number of samples were positive, these taken around patients with very strong symptoms. Furthermore, viruses were detected in the air around COVID-19 positive people who were not hospitalized and had mild symptoms. All samples that were PCR positive were attempted to be cultured; none of these were positive. The results from the project showed no environmental contamination at Oslo Airport, but some positive samples were found at subway stations and in subway cars. As these results are based on a limited data set (434 surface and 135 air samples), they cannot be taken as proof of the absence of infection risk; in addition, the methodology used in the project will not be able to detect direct infection between people, which is considered the most important route of infection. Furthermore, the results indicate that there is a potentially higher risk for healthcare workers when patients are given nebulizer treatment, and that the risk is also higher when the patient has more severe symptoms. More samples taken of air around people with mild symptoms, who are not hospitalized? and which can thus cause the spread of the virus? were also positive. NorCoV2 is led by the Defense Research Institute, in collaboration with the Defense Microbiology Laboratory, Oslo University Hospital, Sporveien AS, and Avinor AS. The NorCoV2 project has also contributed data to an international environmental monitoring project for SARS-CoV-2, under the coordination of the MetaSUB consortium (metasub.org).