tenofovir can be used for hiv prevention in people who are at high risk for infection through sexual transmission or injecting drug use. a cochrane review examined the use of tenofovir for prevention of hiv before exposure and found that both tenofovir alone and the tenofovir/emtricitabine combination decreased the risk of contracting hiv for high risk patients. the u.s. centers for disease control and prevention (cdc) also conducted a study in partnership with the thailand ministry of public health to ascertain the effectiveness of providing people who inject drugs illicitly with daily doses of tenofovir as a prevention measure. the results revealed a 48.9% reduced incidence of the virus among the group of subjects who received the drug in comparison to the control group who received a placebo.