source for this information http://www.mattressfirm.com/flu-on-your-next-flight.html
More than 2500 respondents were surveyed on October 2 6, 2017 with the question, “Would you cancel a nonrefundable flight if you had a cold or the flu?” and 75.1% said “ No.”
Data for germs on a plane was taken from Travelmaths report
TRAVEL TIPS FOR STAYING HEALTHY
1. Stock Up on Sleep: Getting enough sleep before and after a trip is one of the best, easiest, and cheapest ways to boost your immune system to prevent a cold. Sleep deprivation weakens your immune system, making you more susceptible to getting sick, so be sure to take an extra nap or two before your next trip.
2. Wear a Mask: If your immune system is weak or you need to avoid becoming sick at all costs, donning a mask is the way to go. Be sure to get a medical grade N95 mask instead of a disposable paint mask as N95 masks are designed specifically to protect you from germs and other pollutants.
3. Sanitize Your Serving Tray: On your next flight, come prepared with disinfecting wipes to wipe down your seat’s serving tray before use. Do not use the serving tray if you forget to bring wipes. Your immune system will thank you.
4. Use Hand Sanitizer: Germs easily travel between your hands and mouth — especially when eating. As mentioned in the serving tray tip above, be sure to sanitize your hands before eating.
5. Stay Hydrated: Drinking plenty of water several hours before and after your flight is another way to help fight off a cold. When you are dehydrated your immune system is more susceptible to germs. Try to drink about three liters of water a day.
6. Gargle Your Cough Away: While there is little data to back up the idea that rinsing your mouth with mouthwash will stop a cold in its tracks, gargling with hot water and salt can temporarily relieve a sore throat as well as ease a cough you may have caught on your flight.
7. Prioritize Zinc over Vitamin C: If you do catch a cold, or are one of the 75% who choose to fly when sick, skip taking vitamin C (it doesn’t work, really) and opt for Zinc instead, which science suggests helps treat colds more effectively than vitamin C.
8. Switch Seats: If someone audibly and visibly ill sits next to you, and the cabin is not full, politely and quietly ask the flight attendant to switch seats.
9. Get Your Flu Shot: While a flu shot only protects you against a small subset of the flu virus, it is worth the time and investment to shield yourself from the new “big baddies” of the upcoming flu season. If you fly internationally, be sure to also be up to date on the rest of your vaccines.
10. Sleep on the Plane: This is an ideal time to catch up on your sleep — especially if you’ve booked an overnight flight. If you’re a light sleeper, bring a small pillow and blanket with you to help get more comfortable — and don’t forget the earplugs. You’ve got a lot of extra time, and naps are a great way to kill a few hours and recharge — you might as well catch up on your rest.