Question: Could sinuses be a reservoir for virus? Reply: Besides the skin, sinuses are usually the first tissue encountered by airborne viruses and other microorganisms. The sinuses are somewhat unique in that they have a strong immune system designed to destroy invading microbes as well as a mucus physical barrier to trap and remove particulate material and airborne pathogens. However, trapped viruses, bacteria and fungi can also survive and grow in this environment, and when host immune and non-immune systems respond, sinusitis can result. Could this be a reservoir for pathogens? Yes, it could, especially airborne pathogens but possibly others as well.