Researchers are looking into new ways that could protect women, and maybe men, from HIV infections, including tablets, insertable rings and dissolving films. Using such an approach, called a microbicide, could help overcome some risks of drug resistance that can come with taking pills that prevent infection. A flexible ring used in the vagina can continually deliver two AIDS drugs for up to a month, researchers reported, although it hasn’t been tested in people yet. Meanwhile, a vaginal tablet worked in a similar way, using a polymer that attaches to the moist vaginal lining. In another approach, a film that’s smaller and thinner than a stick of gum is used. Microbicides using HIV drugs are expected to represent a large new market for companies that make them.