Nothing…I repeat NONE of the masks in the face diaper category are effective in blocking ANY type of virus. The only thing that would 100% effectively protect you from anything closely relating to this is the hermetically sealed HAZMAT full body suits.
I have many years experience with masking and HAZMAT protective equipment. I have extensive training in every type of mask or breathing apparatus associated with filtration. They lie to you blatantly on television, especially regarding the latest crap about N95 masks. They are not designed to filter any kind of viral contagion. They are mainly designed to prevent anything from doctors or staff from entering a patient, nothing more.