key: cord-0012967-lauw7o1o authors: Küpper, J.-H.; Jung, F.; Krieger, V.; Hufert, F. title: A comparison of COVID-19 mortality rates between European and Asian States date: 2020-07-22 journal: nan DOI: 10.3233/ch-209008 sha: 9e68b94e99388a33114e7c79a3962695b6e55aa5 doc_id: 12967 cord_uid: lauw7o1o nan sneezing. The spread of COVID-19 is assumed to be occurring through aerosols produced by asymptomatic individuals during breathing and speaking [3, 4] . Droplet size, inertia, gravity, and evaporation determines how far emitted droplets or aerosols remain suspended in the air for minutes-to-hours after a cough or sneeze [5] [6] [7] . Droplets sediment fast, contaminate surfaces and lead to contact transmission while aerosols accumulate in indoor air for hours, remain infectious and can be inhaled deep into the lungs. Thus, two respiratory virus transmission pathways exist: contact (between people and with contaminated surfaces) and airborne inhalation. The transmission of the SARS-Cov2 virus is discussed to occur largely via large cough or sneeze droplets, which comprise the vast portion of the sprayed liquid in cough/sneeze and will land in the nasopharynx due to their size -precisely where the receptors for the virus are present, allowing viral attachment and entry into the host cells. Obviously, this route of transmission could be effectively blocked by simple physical barrier like face masks [8] . Therefore, the wearing of face masks might reduce virus infection induced by: i.) direct contact with respiratory secretions such as on hands and surfaces, ii.) the infection of other persons through speaking, coughing, and sneezing, and 3.) the inhalation of aerosols. Indeed, face mask usage has been shown to decrease infection and was successfully implemented during former coronavirus outbreaks (i.e. SARS and MERS [9] ). Asian countries demonstrate that -among continual isolation, prompt identification of cases and contacts, strict quarantines, travel restrictions, social distancing, and personal hygiene -wearing a mask when on public transit or shopping might help to limit the spread of SARS-COV-2 [10] [11] [12] . The findings of a systematic review of 172 studies on COVID-19, SARS, and MERS provide the best available evidence that wearing face masks protects people against infection by coronaviruses (and that eye protection could confer additional benefit) [13] . However, none of these interventions afforded complete protection from infection. Assuming that masks would only reduce transmissions by 22%, then after 10 cycles of the infection, mask-wearing would reduce the level of infection in the population by 91.7%, as compared with a non-mask wearing population [1] . It is highly unlikely that entire countries or populations will ever be randomized to either wear, or not wear, face masks. Therefore, there is not enough data to quantify risk reduction from the use of masks and it is not possible to establish the evidence for wearing masks with certainty. Though masks alone cannot stop the pandemic, studies might indicate that mask wearing should be implemented as early as possible and, especially indoors, should be maintained until the end of the pandemic to successfully combat mortality from SARS-COV-2. The Asian states show that this is possible without a general lock-down. Final Country-wide Mortality from the Novel Coronavirus (COVID-19) Pandemic and Notes Regarding Mask Usage by the Public Herd immunity or suppression strategy to combat COVID-19 Airborne Transmission of SARS-CoV-2: The World Should Face the Reality Consideration of the Aerosol Transmission for COVID-19 and Public Health Recognition of aerosol transmission of infectious agents: A commentary The flow physics of COVID-19 Translating transmissibility measures into recom-mendations for coronavirus prevention Professional and Home-Made Face Masks Reduce Exposure to Respiratory Infections among the General Population Journey through an epidemic: some observations of contrasting public health responses to SARS the-use-of-masks-in-the-community-during-home-care-and-in-healthcare Respiratory virus shedding in exhaled breath and efficacy of face masks Reducing transmission of SARS-CoV-2 Physical distancing, face masks, and eye protection to prevent person-to-person transmission of SARS-CoV-2 and COVID-19: a systematic review and meta-analysis The authors have no conflict of interest to declare.