“My guess is Jet Lag is actually your body fighting off all the virus exposure.”
Plus the dried out air with lower humidity than the Sahara for hours.
That dried out air allows viri to lift off the ventilation surface structures and travel into your lungs. They have to put in viral air filters or stop all flights, due to Corona and whatever else leaked out of that Chinese biomedical lab. I find just spraying lysol into the ventilation system at least wets down the dust and stuff on ventilation surfaces.