I'm very pleased with this purchase. Too early to tell yet how effective it will be, having been only a few days. But this cover is very well made of soft material, and a tight zipper. It is easy to slip on. Mine is for a double bed. If all of the attributes built into the product and material prove accurate, it will be a very good purchase and well worth the cost. In any case it is much better than the old, shreddy, wrinkled un-zippered-in mattress-top covers that I have always used. My mattress is now entirely covered, zipped closed and fits the mattress well so there are no wrinkles under the top sheet.
I don't have allergies but I bought as a precaution. So I can't say it works but it's made well and now I have them on the guest mattresss as well as mine.
Always use on bedding at home and cottage. We have 8 beds and yearly we wash the mattress pads and pillow protectors as was blankets and bedspreads. Always comes out great.