Even though taking a daily pill can protect almost completely against getting H.I.V., a third of primary care doctors and nurses in the United States have never heard of it, federal health officials said this week.

美国的联邦卫生官员在本周表示，虽然每日服用一种药片几乎可以完全预防H.I.V.（人类免疫缺陷病毒）感染，但在美国，有三分之一的初级保健医生和护士从来没有听说过它。

Taking Truvada daily gives better than 90 percent protection to men at risk of getting H.I.V. from gay sex, and better than 70 percent protection to drug injectors at risk of getting it from sharing syringes, according to the Centers for Disease Control and Prevention.

美国疾病控制和预防中心(Centers for Disease Control and Prevention，C.D.C.)称，对于因同性性行为而存在感染风险的男性，每日服用特鲁瓦达(Truvada)可实现90%以上的保护率；对于因共用注射器而有感染风险的注射吸毒者，保护率达70%以上。

“Providers play a central role in increasing awareness and uptake of PrEP,” Dr. Eugene McCray, director of the agency’s division of H.I.V. prevention, said, using the acronym for pre-exposure prophylaxis, as the practice of taking the drug for prevention is known.

“供应商在增进人们对PrEP的了解和接受中发挥了核心作用，”该机构H.I.V.预防部门的主管尤金·麦克雷(Eugene McCray)博士说。由于服用药物预防的做法日渐为人所知，他在谈话中直接使用了“暴露前预防”的英文缩写。

Truvada is currently the only antiretroviral drug approved by the Food and Drug Administration for PrEP, but its maker, Gilead Sciences, does not advertise it for that purpose. The C.D.C. calculated that about 25 percent of all healthy gay men, 20 percent of all healthy drug injectors and about 0.4 percent of all healthy heterosexual women would benefit from being on the drug; the gay men because they have an infected partner or have unprotected sex with multiple partners, the drug injectors because they share syringes and the women because they have partners who inject drugs or are bisexual. There are an estimated 45,000 new H.I.V. infections in the United States each year.

特鲁瓦达是目前唯一被美国食品和药品监督管理局(Food and Drug Administration, F.D.A.)批准用于PrEP的抗逆转录病毒药物，但它的制造商吉利德科学公司(Gilead Sciences)却未曾给它的这一用途做过广告。按照C.D.C.的计算，这种药物可造福于约25%的健康男同性恋者、20%的健康注射吸毒者和约0.4%的健康异性恋女性。男同性恋者的风险在于他们的伴侣有可能是感染者，以及他们可能会与多个性伙伴发生不安全的性行为；注射吸毒者的风险在于共用注射器；而女性的风险在于她们的伴侣可能是注射吸毒者或双性恋者。据估计，美国每年约有4.5万例新发H.I.V.感染。