Aerosols loaded with SARS-CoV-2 are believed to contribute significantly to the spread of the corona pandemic. With the addition of L for ventilation to the existing AHA* rule (AHA+L), the Federal Ministry of Health makes it clear that ventilation is an effective preventive measure. Prof. Dr. Martin Kriegel, head of the Hermann Rietschel Institute of the TU Berlin (HRI), has now developed a calculation model in cooperation with Prof. Dr. David Bermbach (ECDF/TU Berlin), with the support of the Robert Koch Institute, the Charité - Universitätsmedizin Berlin and a Berlin health authority, with which it is possible to predict a potential risk of infection via indoor aerosols. Thus, ventilation measures, the number of contacts and the duration of stay in rooms can be evaluated and adjusted with regard to their preventive character.
Although it is not known how many reproductive viruses are present on aerosol particles and how many of them have to be inhaled to actually trigger COVID-19, it is possible to predict the potential risk of infection via aerosols. These data are difficult to determine and are still not conclusively researched for other infectious diseases, such as influenza (flu). From a medical point of view, there are still some uncertainties in assessing the risk of infection with SARS-CoV-2 via aerosol particles. However, during a pandemic it is crucial to contain the spread of the virus and to find effective preventive measures.
Based on the current state of knowledge about SARS-CoV-2 and the retrospective analysis of twelve small to large outbreaks in Germany and other countries, the team around Martin Kriegel, supported by the Robert Koch Institute, the Charité and a Berlin health authority, was able to develop a model that predicts the potential risk of infection via aerosols.
"Our model has provided four key findings: First, the risk of infection can be reduced very effectively by supplying virus-free air. Secondly, the combined length of stay of an infected person with healthy individuals has a decisive influence on the probability of an infection with COVID-19. This also applies to good ventilation or filtered room air," says Martin Kriegel.
"Thirdly, limiting the number of contacts to contain the pandemic makes a lot of sense, and fourthly, the infection rate via aerosol particles can be minimized with all three measures mentioned above".
In order to make the new model accessible to the public, the HRI, together with Prof. Dr. David Bermbach from the Department of Mobile Cloud Computing at the TU Berlin and the ECDF, has developed a website on which interested parties can make a simplified assessment of the risk of infection via aerosol particles in a specific situation by entering easily accessible data such as room size, number and activity of people and quality of ventilation. (kj).
*Social distancing + hygiene + face covering