One of the measures proposed by the Dutch government to minimise the risk of spreading/acquiring the Covid-19 virus is keeping a distance of 1.5 meters from other people. Similar advice is given in other countries, see this related question.
I understand the mechanism: infected people spread droplets when they sneeze, cough or even speak, these droplets contain enough virus to infect a person that inhales a droplet or maybe rubs it in their eyes or mouth when they touch their face.
But is there any empirical evidence that standing 1.5 meters apart significantly reduces infection risk for airborne diseases? It does not have to be evidence on Covid-19 per se, the flu or the common cold would suffice.