Scientists have known for several months the new coronavirus can become suspended in microdroplets expelled by patients when they speak and breathe, but until now there was no proof that these tiny particles are infectious.

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A new study by scientists at the University of Nebraska that was uploaded to a medical preprint site this week has shown for the first time that SARS-CoV-2 taken from microdroplets, defined as under five microns, can replicate in lab conditions.

This boosts the hypothesis that normal speaking and breathing, not just coughing and sneezing, are responsible for spreading COVID-19—and that infectious doses of the virus can travel distances far greater than the six feet (two meters) urged by social distancing guidelines.