Drink plenty of pure water. Take supplements of vitamins A, C, E and zinc. Echinacea and Goldenseal have also proved helpful. Some folks suggest daily doses of colloidal silver as well as gargling with it. This is not a cure-all, but it will help.
Hot water helps kill bacteria, mold and yeast particles.
If you get a severe sore throat or cough up green phlegm, go to the doctor immediately. Green phlegm means a bacterial infection either in the lungs or in the upper respiratory tract. Bacterial infections multiply rapidly and can only be killed by antibiotics and then, they are not always effective. Based on their published agenda, we know that the US Air Force is currently engaged in extensive weather modification and control techniques. If the purpose were for mass depopulation, one would think that people-dense countries like India, China, Africa and Indonesia would be targeted.