Most often I use vitamins C, D, E, as well as Omega 3 and whey protein. In order not to talk for a long time, I advise you to pay attention to the site https://www.vitaminexpress.org/uk/ where you can find detailed information about vitamins and nutritional supplements that will help strengthen your immunity. You can also order on this site with delivery of these vitamins and nutritional supplements anywhere in the UK.