First and the most important remedy to improve your immune system situation is Garden Sage/Salvia potion remedy.
Here is how to you prepare Sage potion (simple and effective remedy for immunity from different illnesses) : Take a medium pot, fill it up with water, when it starts boiling, add in there 1 tea spoon of Sage herb and keep that water boiling for 3 more minutes. Then remove Sage, and add just one pinch (exactly as much as you can take with 3 fingers) of following herbs: Common Saint-John’s Wort, Pepper Mint (Brandy mint), Common Balm and Chamomile. Drink this potion regularly and none of the illnesses is a threat for you.
Common thyme is an herb that grows in the wild on rocky ground. It has antiseptic quality. During medieval times Wild thyme was used in decoction against coughs and digestive disorders.
"Chew" (kind of filter through your teeth) sunflower oil for 15-20 min. DO NOT SWALLOW. Spit it out after that and rinse your mouth with manganese solution (dissolve few crystals in a glass of water) Do it 2 times a day, and you will boost immune system to a high level dramatically.
Choose immune system remedy that better works for you and use it as often as you can. More remedies are still coming.