Study design: Systematic review and meta-analysis of 21 standard World Health Organization-specific and COVID-19-specific sources through May 3, 2020.Key findings: In a review of 25,697 patients, transmission of viruses was lower with physical distancing of 1 meter or more compared with less than 1 meter. Protection was increased as distance was lengthened (absolute risk, 3% with longer distance vs 13% with shorter distance). Face mask use could result in a large reduction in risk of interaction (adjusted risk, 3% with face masks vs 17% without). There was a stronger association with protection using N95 masks compared with disposable surgical masks or reusable cotton masks. Eye protection also was associated with less infection.Conclusion: These findings support physical distancing of 1 meter or more. Optimum use of face masks and eye protection in public and health care settings should be informed by these findings.Commentary: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causes COVID-19 and is spread person to person through close contact. With no effective pharmacologic interventions or vaccine expected in the near future, reducing the rate of infection (flattening the curve) is a priority. Added benefits are likely with even larger physical distances, such as 2 meters (6 feet, which we keep hearing about) or more. The use of face masks, including N95 and surgical or similar masks (12-to 16-layer cotton or gauze masks), and eye protection is clearly beneficial. For the general public, this report confirms previous recommendations that physical distancing of more than 1 meter is highly effective and that face masks are associated with protection. Other basic measures, such as hand hygiene, are still needed.I am growing more disheartened by my fellow man (and woman) as things open up during the pandemic. This past weekend, I went to a barbecue outside of Philadelphia, which was attended by many physicians, and to my older brother's outdoor 70th birthday party in northern New Jersey, which was especially hard-hit by the virus. At both events, none of the guests wore masks but would sidle up to my wife, my son, and me as if everything were normal. I can think of four reasons that people would not follow recommendations such as maintaining at least 3-to 6-foot distancing and wearing face masks: (1) they know they don't have the virus (even without being tested); (2) they know they won't get sick because they're young, or they're older but otherwise healthy; (3) they don't believe the science (I don't have patience for these people); or (4) they believe we are all going to get the virus anyway, so get it over with and let's move on (I know very intelligent people who support this last reason). I don't want to tread political waters, but I wish these individuals would acknowledge there may be others who don't agree with this laissez-faire reasoning. Some people may want to maintain social distancing at an outdoor eventdand maybe even wear a face mask.

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Background: In 2020, the severe acute respiratory syndrome coronavirus 2 pandemic caused serious concerns about the availability of face masks. This paper studies the technical feasibility of user-specific face mask production by 3D printing and the effectiveness of these masks. Material & methods: Six different face mask designs were produced by 3D printing and tested by subjective experimenter evaluation and using a respirator fit testing kit. Results were compared with the requirements as given for standard protective face masks. Results: None of the printed masks came anywhere near the required standards for personal protective gear. Conclusion: In spite of their euphoric presentation in the press, none of the currently advertised 3D printed mask designs are suitable as reliable personal protective equipment.

Introduction When deployed abroad, military surgeons frequently have to deal with casualties involving head trauma. The emergency treatments, as well as craniotomies, are often performed by non-neurosurgeons qualified with basic neurotraumatological skills. Previous neurotrauma courses for education of non-neurosurgeons in Germany teach surgical emergency skills but do not include the training of skills needed to successfully utilize imaging in surgical planning, which is of importance for the safety and success of the treatment. To overcome these limitations, 3D printed models of neurotrauma cases were fabricated for application in the training of non-neurosurgeons. Materials and Methods Five models of actual neurotrauma cases from our neurosurgical department were segmented from CT scans and 3D printed using multi-part fused deposition modeling. Model quality was assessed with respect to the representation of pre-defined anatomical landmarks. The models were then fixed to a wooden mount with a central light source and covered by a latex mask for skin simulation. Surgical planning by means of craniometric measurements on the basis of available CT scans of the corresponding patients was then applied to the model. Results The 3D printed models precisely represented the cranium, the lesion, and anatomical landmarks, which are taken into consideration during surgical planning. Surface covering with washable latex masks ensured sufficient masking of the now non-noticeable lesion within the semi-translucent skull. Surgical planning was performed using washable marker drawings. When lighted, the otherwise non-visible lesion within the semi-translucent 3D printed craniums became visible and facilitated immediate success control for the course participants. Conclusion The presented method provided a way to fabricate precise 3D models of neurotrauma cases, which are suitable to teach the application of medical imaging in surgical planning. For further benefit analysis, the application of the presented education tool needs to be investigated within a neurotrauma course.

An amendment to this paper has been published and can be accessed via the original article.