That’s actually funny that this thread came up, I didn’t go to Barcelona but I did catch a cold on my last flight and I am fighting it now. It seems like its 50/50 on if I will catch one when I fly.
Planes recirculate oxygen therefore if one person on the plane has a cold everyone catches it. The funny thing is it would not cost much for airlines to install hepa filters on each plane as to severely reduce infection but they are too cheap for that. It would also make sense for governments to have a mandatory enforcement of this. These filters would be the cheapest way of fighting biological terrorism or natual biological threats from spreading. Airlines have long been considered the biggest threat for infections to spread fast from city to city.