You do have some control over whether you make it through your flight without getting sick:
1. Don't touch your eyes, nose or mouth.
2. Bring a travel-size bottle of hand sanitizer and use it after you've washed your hands in the aircraft lavatory.
3. Stay hydrated. Bottled water is horrible for the environment, but this is one instance when you're allowed to drink it guilt-free.
4. Order your drinks without ice the water onboard is teeming with bacteria.
5. Get up and walk around once an hour. Humans weren't meant to stay in a sitting position for so long.