The Lea Shield is a barrier that covers the cervix. Made of silicone, it does not require fitting by a clinician. It can be used by those allergic to latex and is not damaged by petroleum-based lubricants (34). When it is used with spermicide, it appears to prevent pregnancy at least as well as conventional barrier methods (64, 120, 165). The device is not yet approved by the USFDA for use in the US but is available in Canada and Europe (153).

Femcap is a cervical cap that fits snugly and comfortably but does not grab the cervix as tightly as conventional cervical caps (64, 120, 165). Because it is made of silicone, women allergic to latex can use it. Femcap is awaiting USFDA approval in the US and is not yet available elsewhere.

The Protectaid sponge, which contains three spermicides that may also protect against STIs, works as a contraceptive in three ways: as a barrier that prevents sperm from entering the uterus, as an absorber of semen, and as a spermicide (435). It can be inserted up to 12 hours before intercourse and provides protection for repeated acts of intercourse during that period (120). It can be obtained over the counter in Canada and other countries (40). A similar device, the Today contraceptive sponge, is being reintroduced in the US.

Microbicides. Some see vaginal microbicides—creams, foams, and gels that kill HIV and other STIs and sperm in the—vagina as the future of woman-controlled protection (154, 180). Researchers are developing more than 45 microbicides for possible use against HIV and other STIs, but so far there is no microbicide that is suitable for topical, vaginal, or rectal use and capable of killing or inactivating specific microorganisms, such as HIV or other STIs (474).

Johns Hopkins University scientists have created a new type of contraceptive gel (called BufferGel) that may prevent STIs and pregnancy (116, 571). In early 1999 BufferGel safety studies were near completion in India, Malawi, Thailand, and Zimbabwe, and studies of BufferGel used alone and with a diaphragm also were nearing completion (114).

Microbicides that form a barrier to disease transmission include a polymer-based "liquid condom" being developed at Laval University's Infectious Diseases Research Center in Canada. Applied as a transparent liquid to genital or anal areas before sex, the nontoxic, tasteless material forms a gel at body temperature that physically blocks the transmission of HIV and herpes simplex virus (115, 160, 245). Preclinical trials and the first clinical trial of the gel are nearing completion (56).