has_participant has participant contact and droplet transmission of SARS-CoV-2 droplet nuclei transmission of SARS-CoV-2 A SARS-CoV-2 transmission that occurs through infected droplet nuclei or aerosols, which are droplets <=5 μm in diameter. Droplet nuclei are the residue of dried respiratory aerosols (≤ 5 μm in diameter) that results from evaporation of droplets coughed or sneezed into the atmosphere or by aerosolization of infective material. Oliver He https://apps.who.int/iris/bitstream/handle/10665/112656/9789241507134_eng.pdf https://www.who.int/news-room/commentaries/detail/transmission-of-sars-cov-2-implications-for-infection-prevention-precautions infectious droplet nuclei