The other stops viruses being taken into the cells of the vaginal wall, from which they can spread to the rest of the body.

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But an even less intrusive and to a man invisible form of protection would be a vaginal microbicide that kills the virus before it can cross the vaginal wall.

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It is believed that their strong electric charges attract them either to the viruses (thus inactivating them) or to the cells of the vaginal wall (thus covering those cells like a coat of paint and preventing viruses from entering the body).

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