is that assuming there is someone on the flight with Covid, or does it factor in the probability that the flight is Covid free? Likely the latter, because On the Zante flight 3% boarded with it and 4.5% got it somewhere during the journey. Further, for cash, leaving the centre seat empty halves the risk. Which takes us back to coaches and long distance trains where every other seat is blocked.... I do not understand why KN95 masks are not mandatory on flights.