At your advanced age, your immune system is what it is. If I'm travelling, especially flying, I use "Airborne". You can get it from Trader Joe's. It's a vitamin and immune system booster that has helped me ward off colds my toddler brings home. Have SO take it before leaving and before returning, and maybe you do the same.
Try that, or cut out the tonsil-hockey for a few days after he returns.