According to a study by the Massachusetts Institute of Technology, viral droplets expelled by coughing can create a cloud that spans 8 metres. Virus-containing droplets can then remain drifting in the air for hours, potentially extending the exposure range even further.
Given the turbulent puff cloud dynamic model, recommendations for separations of 3ft to 6ft (1-2 metres) may underestimate the distance, timescale, and persistence over which the cloud and its pathogenic payload travel, thus generating an underappreciated potential exposure range for a healthcare worker.Coronavirus latest: ‘Two metres not enough’ when social distancing. (2020). Retrieved 30 March 2020, from https://www.independent.ie/world-news/coronavirus/two-metres-not-enough-when-social-distancing-39083182.html
Some people, it seems, may need a much larger cardboard disk.
'Two metres not enough' when social distancing: https://www.independent.ie/world-news/coronavirus/two-metres-not-enough-when-social-distancing-39083182.html