Review of the efficacy of HEPA filtered air to control coronavirus risks in cleanrooms

The risk of viral transmission in the built environment is a matter of concern in the era of the novel coronavirus pandemic, for most of society, given that humans spent the majority of their time indoors. For pharmaceuticals and healthcare, there is an additional concern about working in cleanrooms and the degree to which protective measures are appropriate. With cleanrooms, an important concern is with the efficacy of HEPA filters. This article looks at the risks stemming from SARS-CoV-2 and applies these to the cleanroom context. The article concludes that the cleanroom environment does not contribute to the risk of viral transmission, and certain design aspects can, in fact, reduce the risk compared with other built environments. Characteristics of the novel coronavirus Coronaviruses (CoV) are a large family of viruses that cause illness ranging from the common cold to more severe diseases such as Middle East Respiratory Syndrome (MERS-CoV) and SARS-CoV). Coronaviruses are zoonotic, meaning they can be transmitted between animals and people ¹. Coronaviruses are classified as RNA ‘enveloped’ viruses, whereas viruses such as rotavirus, or poliovirus are termed non-enveloped. Enveloped viruses have an envelope or outer coating which is needed by the virus to help it attach to the host cell. If this outer coating is destroyed, for example by a disinfectant, the virus cannot survive. The mode of transmission for enveloped viruses is characterized by the specific virus; however, the most common routes are via indirect or direct contact of infectious virus particles, contact with or inhalation of respiratory droplets ². The specific coronavirus of concern is SARS-CoV-2, with SARS standing for ‘severe acute respiratory syndrome’ and CoV representing ‘coronavirus’. The associated respiratory disease is termed COVID-19 (to represent ‘coronavirus disease 2019). This particular virus can cause severe respiratory disease because cells in the lung are damaged and no longer able to transport oxygen into the bloodstream. Some symptoms of disease such as fever and fatigue result from the activities of the immune system trying to eliminate the infection from the body. Heat (fever) inactivates viruses and fatigue results from the high energy demands of the immune system fighting the virus ³.