Hi OPILOVA,
A mattress protector is always a good idea with any mattress to protect your mattress from stains and the body fluids, skin cells, oils that we release each night, to protect against spills and accidents, and to keep your sleeping surface in a clean and hygienic condition. It will also protect your warranty because mattress warranties are usually voided with any type of stain on a mattress. There is more about the pros and cons of different types of mattress protectors in post #89 here that can help you decide which type would be best for you.
Phoenix