lots of bacteria and viruses in the air and in particles, virus transfer.

air airborne bacteria bacteriological bacterium biology cleanliness coli concept contact corona coronavirus covid19 disease droplets epidemic escherichia eyes face flu global health human hygiene illustration immune infection infectious lips lots medical membranes mers microbes microbiology microscopic microworld migration mucous ncov nose organism organs outbreak pandemic pandemics particles quarantine respiratory retrovirus risk sars sick skin touch transfer tuberculosis various vector virological virology virus viruses