Fair enough, you might say, that isn't nice, but there's probably other sick people on that flight. However, that response is surely begging an interesting moral question: should he (and them) have canceled their trip in order to prevent innocent other air travelers from getting infected by the flu virus? I think that there can be no doubt, passing knowingly such an infection on to other parties in a confined space such an airplane for the duration of several hours constitutes a case of harm to others. Nobody on the plane volunteered to be subjected to that sort of infection risk and almost certainly everybody (not already vaccinated) on that particular flight would have preferred not to have been on that flight, considering the risk of reasonably serious disease. It's not that the flu is 'just' a nasty illness keeping us sick for 10-14 days, no, it actually kills a lot of people each year. Up to 1500 people die each year of flu related complications in Canada alone. Worse, those people infected on the plane, doing what people usually do when they go on Caribbean vacations (eg drink, increase the skin cancer risk by means of roasting in the sun for no good reason, have sex), will almost certainly ensure that folks on Barbados will also pick up the flu from them. A lot of people will get sick as a result of Mr Doe's decision to board a flight to Barbados today.
Well, before the divorce papers arrive in the mail, what reasons could be deployed against this analysis: For starters, the volenti non fit iniuria principle can probably be deployed. After all, we all know prior to boarding planes that there's bound to be some irresponsible passenger or other who dragged his infectious illness onto the plane. Unlike with multiple drug-resistant TB, of course, we can actually protect ourselves against the flu reasonably well, and at low risk for ourselves, simply by getting vaccinated. So, if we board a plane anyway, voluntarily and unprotected, this can arguably be read as consenting to the risk of catching an infection. That doesn't mean that we want it, but we surely didn't go out of our way to prevent it from happening. Another reason in support of Mr Doe's decision to fly anyway, is that most airlines will almost certainly not reimburse for tickets canceled that late in the day, so he would have suffered a substantial financial loss had he chosen to stay in bed. Corporate policies in other words, incentivise people to follow courses of action that are detrimental to public health. Quite possibly some employers might have required him to take his leave anyway, as scheduled, instead of taking sick leave.
All of that is regrettable. Surely we should have policies in place that reward people like Mr Doe for behaving responsibly and in a slightly more caring manner toward fellow travelers. That we do not is remarkably short-sighted.