2025 年 4 月 7 日/作者：Joseph M Yabes, Jr, MD, FACP；編輯：Michael Stuart Bronze，醫學博士，更多…/ Medscape

概述

由於缺乏有效疫苗，2023 年全球將有 130 萬 [100 萬至 170 萬] 人感染愛滋病毒。 [1]

在 PrEP（暴露前預防）中，HIV 陰性但高風險的個體（例如其性伴侶為 HIV 陽性的個體）每天服用抗反轉錄病毒藥物以降低感染病毒的幾率。 [2, 3] 使用抗病毒藥物進行暴露前化學預防已獲得廣泛認可，成為預防高風險族群HIV 新發感染的有效策略。 [4]

原理

由於大多數生物和行為預防策略都未能降低愛滋病毒感染率，抗愛滋病毒療法 (ART) 作為愛滋病毒一級預防手段正日益受到人們的關注。 [5] 此外，有效的預防性疫苗仍需多年時間才能問世。愛滋病毒的性傳播與血液和生殖器分泌物中的愛滋病毒濃度密切相關。越來越多的觀察和建模數據顯示，抗反轉錄病毒藥物 (ARV) 可用於降低慢性愛滋病毒患者的感染率，這可能是透過降低血漿和生殖道愛滋病毒濃度來實現的，同時也可以保護處於危險中的未感染者。 [6] 這種方法的原理是在可能接觸愛滋病毒之前給予預防劑量的抗反轉錄病毒藥物。此策略旨在病毒進入人體後立即抑制其複製，從而防止慢性愛滋病毒感染形成。 [3]

在懷孕期間使用 TDF/FTC PrEP 的愛滋病毒陰性母親所生嬰兒的數據仍然不完整。儘管如此，接受 TDF/FTC 治療的 HIV 陽性女性所生子女尚未報告不良反應。 [2] 隨著抗病毒療法 (ART) 藥物目錄的不斷擴大以及藥物耐受性和可及性的提高，人們越來越樂觀地認為，ART 之暴露前預防 (PrEP) 是一種有效的預防方法，適用於持續存在著HIV 感染風險的個體。

暴露前預防藥物的理想候選藥物

理想的化學預防藥物應具有較長的半衰期，在單核細胞、巨噬細胞和生殖器分泌物中達到高濃度，具有較高的遺傳抗藥性屏障，並且安全且廉價。作為 PrEP 研究最廣泛的抗反轉錄病毒藥物，替諾福韋 ( tenofovir DF ) 就具有許多上述理想特性。目前大多數 PrEP 臨床試驗均涉及替諾福韋合併或不合併恩曲他濱 (emtricitabine)。然而，人們擔心 PrEP 的廣泛使用可能會導致抗藥性菌株的選擇和傳播。蛋白酶抑制劑與蛋白質結合率較高，並達成在生殖道中的濃度可低於替諾福韋。 [7]

馬拉威若 (Maraviroc) 是一種口服 CCR5 輔助受體拮抗劑，可達到良好的生殖器和直腸濃度，可能是 PrEP 的潛在候選藥物。

化學預防上的最佳藥物數量尚不清楚。使用單一藥物的潛在優點包括簡單、藥物毒性風險較低和低成本。如果採取預防措施後仍發生 HIV 感染，則應權衡這些風險與抗藥性風險。如果使用多種藥物進行暴露前預防，這些藥物應在病毒生命週期的不同階段發揮作用，並具有更高的感染遺傳屏障，以降低抗藥性風險。

2012 年 7 月 16 日，FDA 批准了恩曲他濱/替諾福韋 (emtricitabine/tenofovir DF, Truvada) 抗反轉錄病毒組合以及 安全性行為作為PrEP，以降低高風險成年人透過性行為感染 HIV-1 的風險。作為批准條件，FDA 要求 Truvada 的製造商吉利德科學公司針對於服用恩曲他濱/替諾福韋期間感染愛滋病毒的人進行研究，以確定是否有人會對該藥物產生抗藥性。

自從首次發布指南推薦使用恩曲他濱和替諾福韋酯 (emtricitabine and tenofovir disoproxil) 組合作為 PrEP 的首選藥物以來，替諾福韋艾拉酚胺 (tenofovir alafenamide，TAF) 因其更為有利的副作用而成為治療活動性 HIV 疾病的首選藥物之一。 2019 年 10 月，批准每日服用 200 毫克恩曲他濱加 25 毫克丙酚替諾福韋 ﹝emtricitabine 200 mg plus tenofovir alafenamide (AF) 25 mg (Descovy) ﹞，用於高風險成人和青少年 HIV-1 之暴露前預防 (PrEP)，以降低透過性行為感染 HIV-1 的風險，但接受性陰道交的人除外。 [8]

對於大多數使用者而言，丙酚替諾福韋/恩曲他濱 (tenofovir alafenamide/emtricitabine, TAF) 和富馬酸替諾福韋二吡呋酯/恩曲他濱 (tenofovir disoproxil fumarate/emtricitabine ,TDF/FTC) 在暴露前預防  方面的安全性差異在臨床上並不顯著。 [9] 仿製的 TDF 學名藥的出現有望降低 PrEP 成本，但這引發了如人們去推廣 TAF 可能會阻礙全國性 PrEP之推廣的擔憂。

結合 5,000項 研究的資料顯示，主要涉及順性別男同性戀和雙性戀男性，在 1,009 名 PrEP 使用者中，有 277 人改用了 Descovy (TAF)。 [9] 超過一半（56%）的人引用了醫生的建議，而 32% 的人認為 Descovy 比 Truvada (TDF) 更安全。其他原因包括藥片尺寸較小以及有關 Truvada 的負面廣告。

儘管科學界對這兩種配方的安全性達成了共識，但目前的資訊可能暗示 TDF/FTC 的安全性較低，這可能會損害公眾對 TDF 配方之 PrEP 的看法。 [9]

臨床試驗支持暴露前預防和愛滋病毒治療作為預防的措施

研究顯示，抗反轉錄病毒療法可以抑制但不能消除生殖器分泌物中愛滋病毒的脫出。 [10] 針對伴侶的觀察性研究、生態式社區研究和臨床試驗已經證實了 ART 的預防益處。 [11, 12, 13] 多項觀察性研究報告稱，接受抗病毒治療的患者的性伴侶感染 HIV-1 的可能性減少。 [11, 13] 社區生態學研究顯示，擴大使用 ART 後，HIV-1 新病例的發生率有所下降。 [14, 15]

在一項大規模、隨機、對照、跨洲際的試驗中，共有 1750 對血清相異的異性戀和男同性戀伴侶參與，所有指標病例的基線 CD4 細胞數均為 350-550 個/µL，並被隨機分配到立即開始 ART 治療或延遲直到連續兩次測量結果為 200-250 個 CD4 細胞/µL 或出現有愛滋病定義相關疾病才給予治療。所有血清相異的伴侶都接受了預防和依從性諮詢，並獲得了免費保險套。在立即治療組中，超過 1585 人年，發生了一起 HIV 傳播給伴侶的情況，病毒學基因組分析顯示，該病例與指標病例有關。

在延遲治療組中，在 1567 人年中發生了 27 起相關的 HIV 傳播，rate ratio （率比）為 0.04（95% CI 0.00-0.27）。考慮到所有 HIV 感染，延遲組發生了 35 例 HIV 傳播，立即組發生了 4 例（率比為 0.11；95% CI 0.04-0.32）。 [12] 一項包含上述隨機對照實驗 和七項觀察性研究的綜述得出結論，ART 是預防血清相異伴侶感染 HIV 的有效介入措施。他們估計，僅觀察性研究的總體之率比為 0.16（95% CI 0.07, 0.35），支持去使用 PrEP。 [16]

2016 年，HPTN 052 試驗將血清不一致的異性戀伴侶隨機分配，要麼是立即接受 ART 治療，要麼則推遲 ART 治療，直到 CD4 計數降至 250 個細胞/µL 以下或發生愛滋病定義事件。在 1763 對伴侶中，886 對屬於立即組，877 對屬於延遲組；並向所有的伴侶提供有關使用保險套和安全性行為的建議。試驗期間共報告了 46 例基因相關傳播，其中 43 例發生在延遲組，3 例發生在立即組。然而在病毒被抑制的患者中，沒有發生與遺傳學上相關的 HIV 傳播。 [17]

懷孕

2024 年對涉及非洲孕婦的研究進行的一項系統性回顧和統合分析發現，與不使用 PrEP 相比，口服暴露前預防用藥 (PrEP) 對早產 (preterm birth, PTB) 的發生率沒有顯著影響，6 項 隨機控制試驗（勝算比 [OR] 0.73）和 5 項未調整的世代研究（勝算比 [OR]  0.84）證明了這一點。 [18] 然而，在 3 項調整後的世代研究中，口服 PrEP 與降低早產風險有關（調整後勝算比 [aOR] 0.67）。與未使用 PrEP 相比，口服 PrEP 與低出生體重 (LBW)、極低出生體重 (vLBW)、小於胎齡 (SGA) 或新生兒死亡 (NND) 之間沒有關聯。此外，不同形式的 PrEP（口服 TDF/emtricitabine (FTC)、口服 TDF 和替諾福韋陰道凝膠［tenofovir vaginal gel］）之間的比較顯示，早產率沒有差異。類似地，使用達匹韋林陰道環 (dapivirine vaginal ring) 與安慰劑或口服 TDF/FTC PrEP 相比，並未顯示與早產 (preterm birth, PTB)  或 新生兒死亡 (NND) 有任何關聯。關於使用長效卡博特韋注射劑 (CAB-LA ) 則沒有數據。

緩釋型肌肉注射劑之PrEP

2021 年 12 月，FDA 批准緩釋肌肉注射卡博特韋 (Apretude) 用於成人和青少年的 PReP。此藥每 2 個月進行一次臀部肌肉注射。一項第 3 期臨床試驗證明，肌肉注射卡博特韋在預防 HIV 感染方面優於每日口服 TDF-FTC。在審查了第一次預先計畫的中期終點分析結果後，該試驗因療效而提前停止。 [19]

每日口服 PrEP

恩曲他濱/替諾福韋（Truvada）的批准是基於兩項臨床試驗，即暴露前預防倡議 (iPrEx) 試驗和 Partners PrEP 試驗。

首次試驗由美國國家衛生研究院（NIH）和比爾及梅琳達·蓋茲基金會贊助。 iPrEx 跨國研究發現，在研究對象為高風險、HIV 陰性的男性或跨性別女性且與男性發生性行為的人群中，每日一次服用恩曲他濱加富馬酸替諾福韋二吡呋酯 (FTC-TDF) 可使感染 HIV 的風險降低 44%。 [20]

第二個試驗是 Partners PrEP 試驗，由華盛頓大學和比爾及梅琳達蓋茲基金會贊助。在這項對異性戀相異伴侶的試驗中，伴侶其中一方感染了愛滋病毒，且保險套經常地被使用，在使用恩曲他濱/替諾福韋 (emtricitabine/tenofovir) 後，感染愛滋病毒的風險降低了 75%。 [21]

2013 年 6 月 12 日，泰國衛生部和疾病預防控制中心公佈了一項隨機對照試驗的結果，該試驗對每日口服 300 毫克劑量的富馬酸替諾福韋二吡呋酯 (TDF，Viread) 進行了研究，結果顯示該藥物可有效降低注射吸毒者 (IDU) 的愛滋病毒感染率。 [22] 基於這些發現，CDC 更新了 PrEP 的臨時指南，現在建議將替諾福韋/恩曲他濱 (TDF/FTC, Truvada) 作為透過注射非法藥物感染 HIV 高風險族群的幾種預防選擇之一。

研究結果顯示，每日口服 300 毫克替諾福韋 PrEP 可使感染 HIV 的風險降低約 49%。在 2400 名研究參與者中，持續服用該藥物的人具有更高的保護水平。在對已知依從性的參與者進行的單獨分析中，由於觀察到他們服用藥物並且在他們的血液中檢測到替諾福韋，因此感染愛滋病毒的風險降低了約 74%。 [22]

自從這些試驗發表以來，新的數據進一步支持了先前提到的 PrEP 的好處。

PROUD 試驗於 2016 年 1 月發布，是一項在英國 13 家性健康診所進行的實用開放標籤研究。該研究招募了有性生活且在招募前 90 天內曾進行無保護接受型肛交的 MSM。患者被隨機分配接受每日 TDF/FTC 的立即 PrEP 治療或延後 12 個月的治療。該試驗招募了 544 名患者（直接組 279 名，延期組 269 名）。在試驗初期，PrEP 的益處就變得非常明顯，所有患者都接受了治療。立即 PrEP 組共有 3 例感染，而延遲組有 20 例新感染。這使得愛滋病毒之傳播風險降低了 86%。兩組均出現多起性傳播感染 (STI) 病例，並顯示其性行為無明顯變化。這次在真實環境下進行的試驗的成功證明了這些數據的實際適用性。 [23]

IPERGAY 試驗於 2015 年 12 月發布。這項在法國和加拿大進行的試驗旨在測試在高風險 MSM 中按需要、事件驅動方式下使用 TDF/FTC 的有效性。這是一項隨機安慰劑-對照試驗，試驗對象被要求在性行為前後服用 TDF/FTC，對照控制組服用安慰劑。在 414 名隨機患者中，199 名屬於最終治療組，200 名屬於安慰劑組。兩組人都平等地獲得了性教育、保險套和諮詢服務。平均而言，兩組每月服用約 15 片藥。治療組有 2 例 HIV 感染者，安慰劑組有 14 例。治療組中兩名感染愛滋病毒的患者並未積極服用藥物，這意味著感染愛滋病毒的風險降低了 86%。 [24]

雖然這些數據確實具有啟發性，但考慮到患者所進行之性行為的頻率，每週服用的藥片數量平均約為三片，因此很難完全支持所有患者採取按需要之方式服用 PrEP。

雖然上文引用的數據大多涉及成年人，但評估 PrEP 在 15 至 17 歲青少年 MSM 中的安全性和可行性的試驗數據已於 2017 年發表。 [25] 在這項研究中，我們入選了 78 名患者，選擇標準與成人啟動 PrEP 的標準類似，並在每日給予 TDF/FTC。其中有 46 名患者（64%）完成了 48 週的追蹤。大多數參與者體內都檢測到了研究藥物的含量。在符合每週接受四劑或四劑以上之可以達預防之治療要求上，於第 4 週、第 8 週、第 12 週、第 24 週、第 36 週和第 48 週時，分別有 54%、47%、49%、28%、17% 和 22% 的患者檢測到了高水平的替諾福韋，被認為可以高度的預防感染。研究顯示，PrEP 在這群患者中是可行且安全的，儘管依從性似乎隨著時間的推移而下降。這證明在對比成年人時他們可能需要比預期更頻繁地進行追蹤，以提供更有效的照護並確保適當的依從性和保護。

暴露前預防的潛在問題

抗藥性

使用 PrEP 的一個主要擔憂是，如果 HIV 感染傳播，可能會產生獲得性抗藥性。替諾福韋的抗藥性遺傳屏障較高，但恩曲他濱的抗藥性遺傳屏障較低。 iPrEx 試驗對男男性行為者 (MSM) 的化學預防進行了評估，結果未發現任何替諾福韋抗藥性事件。然而，由於介入組患者的依從性較差，因此並不能排除這種可能性。 [20] 隨著抗反轉錄病毒藥物在預防方面的更廣泛使用，抗藥性的出現可能成為未來的潛在問題，儘管這種擔憂尚未成為現實。

據報道，少數採取有效 PrEP 方案的患者出現了 HIV 傳播。這些事件大多涉及具有多類抗藥性突變(multiclass–drug-resistance mutations)的 HIV 的傳播，[26] 這進一步強調了正在接受 PrEP 治療的患者持續使用保險套的必要性。

行為改變

提供 PrEP 可能會鼓勵高風險性活動的增加和肆無忌憚。最近的數據顯示，服用 PrEP 的患者中無保護性行為的發生率增加，這引發了人們對性傳染感染 (STI) 的擔憂。 [27] 越來越多的研究正在評估這些行為改變的影響。

高風險族群

當考慮使用恩曲他濱/替諾福韋進行 PrEP 治療時，識別高風險個體非常重要。高風險患者包括已知伴侶感染 HIV-1 的人，或在高流行區或社交網絡中從事性活動並表現出以下一種或多種情況的人：不堅持使用或不使用保險套、被診斷出罹患有性傳染病、用性交換商品（如金錢、食物、住所或毒品）、使用非法藥物或酒精依賴，或有 監禁的伴侶其HIV-1 感染狀況不明且具有上述任何感染因素。

病患教育和監測

在為 PrEP 開立恩曲他濱/替諾福韋處方時，醫療保健提供者必須 [28] ：

• 將恩曲他濱/替諾福韋作為綜合性預防策略當中的一部分，因為這種藥物組合並不總是有效地預防HIV-1感染。

• 建議所有未感染者嚴格遵守建議的恩曲他濱/替諾福韋之給藥方案，因為 Truvada 在降低感染 HIV-1 風險方面的有效性與依從性有密切相關，這已由臨床試驗中可測量的藥物水平證明。

• 在開始使用恩曲他濱/替諾福韋作為PrEP 適用之前，應立即確認 HIV-1 檢測呈陰性。如果出現與急性病毒感染一致的臨床症狀，並且懷疑近期（<1 個月）接觸過病毒，則應將開始 PrEP 治療至少延遲 1 個月，並重新確認 HIV-1 狀態，或使用 FDA 批准的測試作為輔助診斷 HIV-1 感染，包括急性或原發性 HIV-1 感染。

美國CDC 暴露前預防指南和評估

美國疾病管制與預防中心於 2014 年 5 月首次發布了暴露前預防 (PrEP) 指引。該指南於 2017 年進行了更新，以納入不斷增長的數據。 [29] 每日口服 PrEP，即富馬酸替諾福韋二吡呋酯 (TDF) 300 毫克和恩曲他濱 (FTC) 200 毫克的固定劑量組合（Truvada），已被證明可安全有效地降低體重至少 35 公斤的成年人和青少年透過性行為感染 HIV 的風險。每日服用恩曲他濱/替諾福韋是愛滋病毒預防一般指引中的預防選擇。

2019 年 10 月，FDA 批准了替諾福韋艾拉酚胺 (TAF) 25 毫克加 FTC 200 毫克 (Descovy) 的固定劑量組合，用於高風險成人和青少年的 HIV-1 暴露前預防 (PrEP)，以降低透過性行為感染 HIV-1 的風險，但不包括接受型陰道性交的人。 [8]

2021年，CDC更新了預防HIV感染的暴露前預防指引。 [30]

有三種經 FDA 批准的 PrEP 藥物可供選擇：

每日服用一次，包含不同藥物組合所形成的一片每日口服藥片有兩種。第三種是每兩個月注射一次的藥物。它們被批准用於預防體重至少 77 磅（35 公斤）的成人和青少年感染愛滋病毒。

• 恩曲他濱 (F) 200 毫克與富馬酸替諾福韋二吡呋酯 (TDF) 300 毫克聯合使用（F/TDF – 品牌名 Truvada® 或其同藥效學名藥）。建議所有有性行為或注射毒品風險因子的個體每天口服 F/TDF 進行 PrEP 以預防愛滋病毒。

• 恩曲他濱 (F) 200 毫克與替諾福韋艾拉酚胺 (TAF) 25 毫克合併使用（F/TAF – 品牌名稱 Descovy®）。建議每日口服 F/TAF 的 PrEP 來預防經由性行為傳染的愛滋病毒，但可能因透過陰道接受型性交而感染愛滋病毒的個體除外。針對F/TAF用於出生時被指定為女性，可能透過接受性陰道交感染愛滋病毒的個體，其對愛滋病毒的預防作用則尚未有研究進行過。

• 卡博特韋 (CAB) 600 毫克注射（品牌名稱 Apretude®）。建議注射含有 CAB 的 PrEP 來預防所有人之間的性行為傳播。 CAB 以肌肉注射的方式給藥。 PrEP 的 CAB 治療從第一次注射開始，然後在第一次注射後 1 個月進行第二次注射。此後每 2 個月注射一次 CAB。

該指南適用於以下特定族群：

• 有性生活且與男性發生性行為的成年男性 (MSM) 感染愛滋病毒的風險很大；證據等級IA

• 感染愛滋病毒風險較高的成年異性性行為的男性和女性；證據等級IA

• 成年注射毒品者（IDU）感染愛滋病毒的風險很大；證據等級IA

• 有異性戀行為的女性和男性，其伴侶已知感染了愛滋病毒（愛滋病毒相異的伴侶）；應該與這類人群討論 PrEP，將其作為在受孕和懷孕期間保護未感染伴侶的幾種選擇之一，以便在了解 PrEP 對母親和胎兒的益處和風險的已知和未知信息的情況下，做出明智的決定；證據級別IIB

PrEP治療指引包括：

• 應向所有有性生活的成年人和青少年提供有關 PrEP 的資訊。

• 對於男性和女性，建議對體重至少 35 公斤（77 磅）的性活躍成年人和青少年，進行每日 F/TDF 的 PrEP 以預防 HIV，如果這些成年人和青少年報告其性行為使他們面臨持續感染 HIV 的巨大風險。

• 對於男性和女性，建議體重至少 35 公斤（77 磅）的注射毒品 (PWID) 的成年人和青少年（也稱為注射吸毒者 [IDU]），並報告其注射行為使他們面臨持續感染 HIV 的巨大風險，每天服用含有 F/TDF 的 PrEP 來預防 HIV，。

• 僅限男性，對於體重至少 35 公斤（77 磅）且有性生活，且報告其性行為使其有面臨持續 HIV 暴露和感染的巨大風險之成年人和青少年，建議每日口服 F/TAF 作為 HIV 預防選擇。 PrEP 與 F/TAF 尚未在女性（出生時被指定為女性，且性別認同為女性的人）中進行研究，因此 F/TAF 是不建議女性或其他因接受性陰道性交，而有面臨愛滋病毒感染風險的人使用本藥品進行愛滋病毒預防。

• 對於與男性發生性行為的跨性別女性（出生時被指定為男性但性別認同為女性的人），如果她們報告的性行為使她們面臨持續感染 HIV 的巨大風險，建議每日口服 F/TAF 的 PrEP 來預防 HIV。

• 其他每日口服抗愛滋病毒藥物（無論是替代 F/TDF 或 F/TAF 或是補充 F/TDF 或 F/TAF）的 PrEP， 因其療效和安全性尚未廣泛研究，因此不建議使用。

對於每日口服 F/TDF 或 F/TAF 的 PrEP 患者，應透過基準線估計肌酸酐清除率 (eCrCl) 來評估腎功能，並定期監測，以便出現臨床顯著腎功能障礙的患者不要繼續服用該藥物。

• 對於年齡超過 50 歲的患者或開始時 eCrCl < 90 ml/min 的患者，應每 6 個月評估一次估計肌酸酐清除率 (eCrCl)。

• 對於所有其他每日口服 PrEP 患者，應至少每 12 個月評估一次 eCrCl。

對報告其性行為使他們面臨持續 HIV 暴露和感染巨大風險的成人和青少年，建議採用肌肉注射卡博特韋 (CAB) 的 PrEP 來預防 HIV。

在開立任何 PrEP 方案之前，必須立即以症狀史和 HIV 檢測排除急性和慢性 HIV 感染。

對於每日口服 PrEP 的患者，應至少每 3 個月評估一次 HIV 感染情況，對於接受 CAB 注射 PrEP 的患者，應每 2 個月評估一次 HIV 感染情況，以確保已感染者不再繼續服用 PrEP。 F/TDF 或 F/TAF 兩種藥物療法和單一藥物 CAB 不足以治療已確診的 HIV 感染，對早期 HIV 感染者使用這兩種藥物可能會對一種或多種 PrEP 藥物產生抗藥性。

當開立 PrEP 處方時，臨床醫師應直接或透過協助轉診提供以下服務：

• 支持藥物依從性和後續 PrEP 照護的持續性，因為高藥物依從性和持續使用對於 PrEP 預防 HIV 感染的有效性至關重要。

• 根據報告的 HIV 暴露傾向行為，提供額外且已被證實有效的降低風險服務，以便將 PrEP 與其他有效的預防方法結合使用，從而降低透過性行為感染 STI 或透過注射毒品感染血源性細菌和病毒感染的風險。

英國愛滋病協會 (BHIVA)/英國性健康與愛滋病協會 (BASHH) 的 PrEP 指南

英國愛滋病協會 (BHIVA)/英國性健康與愛滋病協會 (BASHH) 於 2019 年 3 月發布了有關使用愛滋病毒暴露前預防 (PrEP) 的指南。 [31]

針對男男性行為者 (MSM) 的 PrEP 建議

對於 HIV 陰性的 MSM，如果由於過去 6 個月內進行過無保護套肛交並且正在持續進行無保護套肛交而導致感染 HIV 的風險增加，則應每天或按需要為其提供口服替諾福韋二吡呋酯/恩曲他濱 (TD-FTC) 作為 PrEP。

如果 HIV 陰性的 MSM 與 HIV 陽性的伴侶進行無保護套肛交，則應每天或按需要提供口服 TD-FTC 作為 PrEP，除非該伴侶已接受抗反轉錄病毒療法 (ART) 至少 6 個月且血漿病毒載量 < 200 拷貝/毫升。

異性戀者的 PrEP 建議

HIV 陰性的異性戀男性和女性與 HIV 陽性的伴侶進行無保護性交時，應每日口服 TD-FTC 作為 PrEP，除非伴侶已接受 ART 治療至少 6 個月且血漿病毒載量 < 200 拷貝/毫升。

對於具有持續 HIV 感染風險因子的異性戀男性和女性，應根據個案個別之具體情況 (case‐by‐case basis) 提供每日口服 TD-FTC 作為 PrEP。

如果有 FTC 禁忌症，可以單獨向異性戀男性和女性提供富馬酸替諾福韋二吡呋酯 (Tenofovir disoproxil fumarate, TDF)。

跨性別女性的 PrEP 建議

HIV 陰性的跨性別女性，如果在過去 6 個月內透過無保護套肛交以及持續進行無保護套性交而感染 HIV 的風險增加，則應每天口服 TD-FTC 作為 PrEP。

HIV 陰性的跨性別女性和跨性別男性與 HIV 陽性的伴侶進行無保護性交時，應每日口服 TD-FTC 作為 PrEP，除非伴侶已接受 ART 治療至少 6 個月且血漿病毒載量 < 200 拷貝/毫升。

針對年輕人的 PrEP 建議

對於 HIV 陰性的年輕 MSM（15-25 歲），如果由於過去 6 個月內進行過無保護套肛交並且正在持續進行無保護套肛交而導致感染 HIV 的風險增加，則應每天或按需提供口服 TD-FTC 作為 PrEP。

HIV 陰性的年輕人與 HIV 陽性的伴侶進行無保護性肛交時，應提供 TD-FTC 作為 PrEP，除非該伴侶已接受 ART至少 6 個月，且血漿病毒量 < 200 拷貝/毫升。

對於 HIV 陰性的年輕跨性別女性，如果由於過去 6 個月內進行過無保護套肛交並且正在持續進行無保套肛交而導致感染 HIV 的風險增加，則應每天為其提供口服 TD-FTC 作為 PrEP。

開始並停止 PrEP 的建議

如果肛交有 HIV 感染風險，則可以在性交前 2-24 小時服用雙倍劑量的 TD-FTC 來開始 PrEP，並每天持續服用，直至最後一次性交風險發生後的 48 小時。

如果肛交的 PrEP 已中斷，但距離上次服用 TD-FTC 不到 7 天，則可以透過單劑量 TD-FTC 重新啟動 PrEP。

如果陰道性交有感染愛滋病毒的風險，則應在可能的暴露風險發生前 7 天開始每天進行 PrEP 治療，並在最後一次性接觸風險發生後繼續每天進行 7 天。

基準線測試的建議

在開始 PrEP 之前，應進行基礎 HIV 檢測，包括抗原/抗體血清學聯合檢測。

如果個人在同一天進行的第三代或更高代血液一站式即時檢測 (POCT) 的結果為陰性，或在過去 4 週內進行的 HIV 抗原/抗體聯合檢測的結果為陰性，則可以在同一天開始 PrEP 治療。

如果在過去 4 週內發生過高風險暴露，則應考慮 HIV 病毒量檢測。

對於報告在過去 4 週內進行過無保護肛交且出現提示 HIV 血清轉換症狀的個人，應延後 PrEP 治療，直到獲得 HIV RNA 結果為止。

對於B型肝炎病毒（HBV）感染狀況不明的個體，應進行基準線B肝病毒（HBV）篩檢，對於無免疫力的個體，應開始接種疫苗。

病毒性肝炎/合併感染專家應評估有慢性B型肝炎感染證據的患者，以決定是否繼續或終止治療。

患有慢性 HBV 感染的個人不應向其提供按需要方式之PrEP 劑量。

MSM 和其他有感染C型肝炎病毒 (HCV) 風險的個體應接受基準線之 HCV 篩檢。

應進行全面的基準線之性傳播感染 (STI) 篩檢，包括梅毒血清學檢查和暴露部位（生殖器、直腸、咽部）的淋病雙球菌和披衣菌感染核酸擴增檢測 (NAAT)。

應透過血清肌酸酐檢測、估計腎小球濾過率 (eGFR) 和尿液分析來評估其基準線之腎功能；在等待結果期間可以啟動 PrEP。

開始使用 TDF 治療的患者，eGFR 應 >60 mL/min/1.73 m2。如果 eGFR 低於此值，則應根據具體情況考慮使用 PrEP。

PrEP 依從性不佳

如果每週服用的每日 PrEP 劑量少於四劑，則不太可能有效。儘管如此，沒有證據顯示每週服用四劑而不是七劑就足夠了。

PrEP 期間的監測建議

接受 PrEP 治療的個人應每 3 個月接受一次 HIV 檢測，包括實驗室合併 HIV 抗原/抗體檢測或基於血液的 一站式即時檢測 (POCT)。

接受 PrEP 治療且症狀提示 HIV 血清轉換的個體應接受 HIV 抗原/抗體合併檢測和 HIV 病毒量檢測。

如果確診為原發性 HIV 感染，應進行基準線抗藥性測試，以評估替諾福韋或恩曲他濱 (tenofovir or emtricitabine) 抗藥性相關突變以及其他突變的證據。

所有接受 PrEP 治療的個體都應每 3 個月接受一次細菌性性傳播感染 ( bacterial STIs) 篩檢。 MSM、跨性別女性和其他具有持續 HCV 風險的族群也應每 3 個月進行一次 HCV 檢測。

終止 PrEP 的建議

如果愛滋病毒檢測結果呈陽性，則應停止 PrEP，並應立即將患者轉診給愛滋病毒專家。

對 PrEP 的依從性不佳是繼續使用的相對禁忌症。

對於未獲得B肝疫苗誘發免疫力的患者，停用 TD-FTC 前應排除 HBV 感染。

美國預防服務工作小組建議聲明

美國預防服務工作小組（USPSTF）於2023年8月22日發表聲明，建議對感染風險較高的人提供HIV感染的暴露前預防（PrEP）。 [32]

根據《平價醫療法案》的規定，PrEP 建議也意味著私人保險公司將被要求承擔 PrEP 藥物的費用。

面臨愛滋病毒感染風險的個體包括男男性行為者（MSM）、因異性性接觸而面臨風險的個體以及注射毒品的個體。某些風險因素或行為會進一步增加感染的可能性。

風險評估

具有性生活且至少符合下列一項標準的 MSM 應考慮接受 PrEP：

• 與 HIV 感染的伴侶有性關係

• 報告指出在肛交（接受或插入）過程中沒有持續一致地使用保險套

•過去 6 個月內曾罹患有性傳播感染疾病（STI；梅毒、淋病或披衣菌感染）

符合以下條件之一的異性戀活躍男性和女性應考慮接受 PrEP：

• 與 HIV 感染的伴侶有性關係

• 報告指出在與愛滋病毒感染狀況不明且被認為具有高風險的伴侶（例如，與男性和女性發生性關係的男性或注射毒品者）發生性關係時沒有堅持使用保險套

• 過去 6 個月內曾經罹患性傳播感染（梅毒或淋病）

注射毒品並符合以下標準之一的個人應考慮接受 PreP：

• 共用毒品注射設備

• 有透過性行為感染愛滋病毒的風險

跨性別女性和從事性交易（例如，為了金錢、毒品或住房）的個人，包括商業性工作者或被販賣從事性工作的人，感染愛滋病毒的風險很高。根據上述標準，他們也應考慮接受 PrEP 治療。

預防性藥物

每日一次口服富馬酸替諾福韋二吡呋酯和恩曲他濱 (tenofovir disoproxil fumarate and emtricitabine) 合併用藥是美國 FDA 核准的唯一一種用於治療有透過性傳播而感染HIV風險族群的 PrEP 製劑。

意識到和適應症

據估計，大約 25% 的 MSM 和 19% 的注射毒品使用者有資格接受每日 PrEP。 [33] 儘管有這些數字，並且有跡象顯示在讓符合條件的患者接受照護方面總體取得了進展，[34] 但仍有相當多的高風險患者不知道有 PrEP 可用。在一些風險最高的人群中尤其如此，例如黑人 MSM。 [35] 持續努力對提供者進行教育對於成功實施這些計畫至關重要。

結論

透過治療來預防 HIV-1 感染的想法引起了極大的熱情，其驅動力是：a) 行為和生物預防措施的失敗； b) 使用抗反轉錄病毒療法進行預防的生物學可行性； c) 更便宜、更安全、更簡單的抗反轉錄病毒治療方案； d) 最近的臨床試驗顯示介入措施有希望。

PrEP有可能有助於有效、安全地預防 HIV ，當其係  1) 針對 HIV 感染高風險個體時； 2) 作為全面預防服務的一部分提供，包括降低風險和 PrEP 藥物依從性諮詢、隨時提供保險套以及性傳播感染的診斷和治療； 3）並定期監測HIV狀況、副作用、依從性和危險行為。

FDA 批准恩曲他濱/替諾福韋（Truvada）用於 PrEP，為男男性行為者及血清相異的伴侶等高危險群提供了選擇。此外，目前 CDC 指南還涵蓋了其他族群（例如靜脈注射毒品使用者、異性戀高危險群者）。

儘管 PrEP 前景光明且取得了進展，但人們仍然擔心保護的持久性、早期治療帶來的益處和不良事件的平衡，以及長期堅持和向伴侶傳播 ART 抗藥性病毒株的問題。需要進行長期研究，但不應妨礙該策略的實施。隨著對有效疫苗的探索不斷深入，PrEP 等介入措施可能會顯著減緩愛滋病毒的流行。

Preexposure HIV Prophylaxis

Updated: Apr 07, 2025 / Author: Joseph M Yabes, Jr, MD, FACP; Chief Editor: Michael Stuart Bronze, MD  more… / Medscape

Overview

1.3 million [1.0–1.7 million] people acquired HIV in 2023 worldwide in the absence of an effective vaccine. ^[1]  

In PrEP (pre-exposure prophylaxis), individuals who are HIV-negative but at high risk—such as those with an HIV-positive sexual partner—take an antiretroviral medication daily to lower their chances of contracting the virus. ^[2, 3] The use of antiretroviral medications for pre-exposure chemoprophylaxis has gained significant recognition as an effective strategy for preventing new HIV infections in at-risk populations. ^[4]

 Rationale

Antiretroviral therapy (ART) for primary prevention of HIV is gaining enthusiasm because most biological and behavioral preventive strategies have failed to decrease HIV acquisition. ^[5] Moreover, an effective preventive vaccine remains years away. Sexual transmission of HIV is strongly correlated with concentration of HIV in the blood and in genital secretions. Growing observational and modeling data suggest that antiretrovirals (ARVs) can be used to decrease infectivity of patients with chronic HIV, presumably by decreasing plasma and genital tract HIV concentrations, and also to protect at-risk uninfected individuals. ^[6]  The rationale for this approach is to administer a prophylactic dose of antiretroviral medication prior to potential exposure to HIV. This strategy aims to inhibit viral replication immediately upon entry into the body, thereby preventing the establishment of a chronic HIV infection. ^[3]

Data on infants born to HIV-negative mothers who used TDF/FTC PrEP during pregnancy is still incomplete. Nevertheless, there have been no reported adverse effects in children born to HIV-positive women who received TDF/FTC treatment. ^[2] With the ever-expanding formulary and increased tolerability and availability of drugs, optimism is growing regarding ART preexposure prophylaxis (PrEP) being an effective method for primary prevention for individuals with ongoing risks for becoming infected with HIV.

Ideal Drug Candidate for the Preexposure Agent

The ideal chemoprophylactic agent should have a long half-life, achieve high concentrations in monocytes, macrophages, and genital secretions, have a high barrier for genetic resistance, and should be safe and inexpensive. The most widely studied ARV for PrEP, tenofovir DF, has many of these desirable characteristics. Most of the current clinical trials of PrEP involve tenofovir with or without emtricitabine. However, concerns exist that widespread use of PrEP could result in the selection and transmission of drug-resistant strains. Protease inhibitors are highly protein bound and achieve lower concentrations in the genital tract than tenofovir. ^[7]  

Maraviroc, an oral CCR5 co-receptor antagonist, achieves good genital and rectal concentrations and could be a potential candidate drug for PrEP.

The optimal number of drugs for chemoprophylaxis is unknown. The potential advantages of using a single agent include simplicity, lower risk for drug toxicity, and cost. These should be weighed against the risk for drug resistance if HIV infection occurs despite prophylaxis. If more than one drug is used for preexposure prophylaxis, they should work at different stages of the viral life cycle and have a higher genetic barrier to infection to decrease the risk for drug resistance.

On July 16, 2012, the FDA approved the antiretroviral combination of emtricitabine/tenofovir DF (Truvada), along with safe sex practices for PrEP to reduce the risk for sexually acquired HIV-1 in adults at high risk. As a condition of approval, the FDA requires Truvada’s manufacturer, Gilead Sciences, to study those who acquire HIV while taking emtricitabine/tenofovir to determine if anyone can develop a resistance to the drug. 

Since the initial publication of guidelines recommending the combination of emtricitabine and tenofovir disoproxil as the agent of choice for PrEP, tenofovir alafenamide (TAF) has become one of the drugs of choice for treatment of active HIV disease, given its more favorable side-effect profile. Daily administration of emtricitabine 200 mg plus tenofovir alafenamide (AF) 25 mg (Descovy) was approved in October 2019 for at-risk adults and adolescents for HIV-1 pre-exposure prophylaxis (PrEP) to reduce the risk of HIV-1 infection from sex, excluding those who have receptive vaginal sex. ^[8]

The safety differences between tenofovir alafenamide/emtricitabine (TAF) and tenofovir disoproxil fumarate/emtricitabine (TDF/FTC) in pre-exposure prophylaxis (PrEP) are clinically insignificant for most users. ^[9] The availability of generic TDF is expected to reduce PrEP costs, raising concerns that promoting TAF may hinder national PrEP expansion.

Data from the Together 5,000 study, involving primarily cisgender gay and bisexual men, revealed that among 1,009 PrEP users, 277 switched to Descovy (TAF). ^[9] Over half (56%) cited their doctor’s recommendation, whereas 32% believed Descovy was safer than Truvada (TDF). Other reasons included the smaller pill size and negative advertising about Truvada.

Despite scientific consensus on the safety of both formulations, current messaging may imply that TDF/FTC is less safe, potentially damaging public perception of TDF-formulated PrEP. ^[9]

Clinical Trials Supporting Preexposure Prophylaxis and HIV Treatment as Prevention

ART has been shown to suppress but not eliminate the shedding of HIV in genital secretions. ^[10] The preventive benefits of ART have been shown in observational studies involving couples, ecologic community studies, and in a clinical trial. ^{[11, 12, 13]}  Several observational studies have reported decreased acquisition of HIV-1 by sexual partners of patients receiving antiretroviral therapy. ^[11, 13] Ecologic studies in the community have shown a reduction in the incidence of new cases of HIV-1 after expanded use of ART. ^[14, 15]

In a large, randomized, controlled, multicontinental, trial that enrolled 1750 serodiscordant heterosexual and male homosexual couples, all index cases had 350-550 CD4 cells/µL at baseline and were randomly assigned to immediate ART treatment initiation or delayed treatment until 2 consecutive measurements of 200-250 CD4 cells/µL or an AIDS-defining illness. All serodiscordant couples were given prevention and adherence counseling and provided with free condoms. In the immediate treatment arm, over 1585 person years, one HIV transmission to a partner occurred that was linked by virological genomic analysis to that of the index case.

In the delayed treatment arm, over 1567 person years, 27 linked HIV transmissions occurred, yielding a rate ratio of 0.04 (95% CI 0.00-0.27). When considering all HIV infections, 35 HIV transmissions occurred in the delayed arm and four transmissions in the immediate arm (rate ratio 0.11; 95% CI 0.04-0.32). ^[12] A review that included the above RCT and seven observational studies, concluded that ART is a potent intervention for prevention of HIV in discordant couples. They estimated a summary rate ratio of 0.16 (95% CI 0.07, 0.35) for the observational studies alone in favor of using PrEP. ^[16]

In 2016, the HPTN 052 trial randomized serodiscordant heterosexual couples either to receive immediate ART initiation or to defer ART therapy until CD4 counts fell below 250 cells/µL or an AIDS-defining event occurred. Among 1763 couples, 886 were in the immediate arm and 877 were in the delayed arm. Couples were counseled regarding condom use and safe sexual practices. A total of 46 genetically linked transmissions were reported during the trial period, of which 43 occurred in the delayed arm versus three in the immediate arm. No genetically linked HIV transmissions occurred among patients who were virologically suppressed. ^[17]

Pregnancy

A 2024 systematic review and meta-analysis of studies involving pregnant women in Africa found that oral pre-exposure prophylaxis (PrEP) did not significantly affect the incidence of preterm birth (PTB) compared to no PrEP, as evidenced by 6 RCTs (odds ratio [OR] 0.73) and 5 unadjusted cohort studies (OR 0.84). ^[18] However, in 3 adjusted cohort studies, oral PrEP was associated with a reduced risk for PTB (adjusted odds ratio [aOR] 0.67). No associations were found between oral PrEP and low birth weight (LBW), very low birth weight (vLBW), small for gestational age (SGA), or neonatal death (NND) when compared to no PrEP. Additionally, comparisons among different forms of PrEP—oral TDF/emtricitabine (FTC), oral TDF, and tenofovir vaginal gel—showed no differences in PTB rates. Similarly, the use of the dapivirine vaginal ring did not show any association with PTB or NND when compared to placebo or oral TDF/FTC PrEP. No data were available on the use of CAB-LA.

Extended-release IM injection for PrEP

An extended-release IM injection, cabotegravir (Apretude), was approved by the FDA for PReP for adults and adolescents in December 2021. It is administered as a gluteal IM injection every 2 months. A phase 3 clinical trial demonstrated cabotegravir IM was superior to daily oral TDF-FTC in preventing HIV infection. The trial was stopped early for efficacy on review of the results of the first preplanned interim end-point analysis. ^[19]  

Daily oral PrEP

The approval of emtricitabine/tenofovir (Truvada) was based on two clinical trials, the Pre-exposure Prophylaxis Initiative (iPrEx) trial and the Partners PrEP trial.

The first trial was sponsored by the US National Institutes of Health (NIH) and the Bill and Melinda Gates Foundation. The iPrEx multinational study found that once-daily emtricitabine plus tenofovir disoproxil fumarate (FTC-TDF) reduced the risk of acquiring HIV by 44% in a study population of high-risk, HIV-negative men or transgender women who have sex with men. ^[20]

The second trial is the Partners PrEP trial, sponsored by the University of Washington and the Bill and Melinda Gates Foundation. In this trial of heterosexual couples where one partner was infected and condoms were used routinely, a 75% reduction was observed in risk of acquiring HIV infection with use of emtricitabine/tenofovir. ^[21]

On June 12, 2013, the Thailand Ministry of Health and the CDC published results from a randomized controlled trial of a daily oral dose of 300 mg of tenofovir disoproxil fumarate (TDF, Viread) that showed efficacy in reducing the acquisition of HIV infection among injecting drug users (IDUs). ^[22] Based on these findings, the CDC updated its interim guidance for PrEP and now recommends that tenofovir/emtricitabine (TDF/FTC, Truvada) be considered as one of several prevention options for persons at very high risk for HIV acquisition through the injection of illicit drugs.

Results showed that daily oral PrEP with tenofovir 300 mg reduced the risk of acquiring HIV by approximately 49%. Among 2400 study participants, those who took the medication consistently had higher levels of protection. In a separate analysis of participants known to be adherent, because they were observed taking their medication and had tenofovir detected in their blood, the risk of HIV acquisition was reduced by approximately 74%. ^[22]

Since the publication of these trials, new data have further supported the previously noted benefits of PrEP.

The PROUD trial, published in January 2016, was a pragmatic open-label study performed in 13 sexual health clinics in the United Kingdom. The study enrolled MSM who were sexually active and practicing receptive condomless anal sex during the 90 days prior to recruitment. Patients were randomly assigned to receive immediate PrEP with daily TDF/FTC or to defer treatment for 12 months. The trial enrolled 544 patients (279 in the immediate group, 269 deferred). Early during the trial, the benefit of PrEP became overwhelmingly evident, and all patients were offered treatment. The immediate PrEP arm had a total of three infections, whereas the deferred arm had 20 new infections. This resulted in an 86% risk reduction for HIV transmission. Both groups experienced many cases of STI and showed no significant change in sexual behavior. The success of this trial, which was conducted under real-world circumstances, speaks to the practical applicability of these data. ^[23]

The IPERGAY trial was published in December 2015. This trial, performed in France and Canada, sought to test the efficacy of on-demand, event-driven use of TDF/FTC among high-risk MSM. It was a randomized placebo-controlled trial in which individuals were instructed to take TDF/FTC preceding and after sex versus placebo. Of 414 randomized patients, 199 were in the final treatment group and 200 were in the placebo group. Sexual education, condoms, and counseling were offered equally to both groups. On average, both groups took approximately 15 pills per month. There were two HIV infections in the treatment arm and 14 in the placebo group. The two patients who became infected in the treatment arm were not actively taking medications, amounting to an 86% risk reduction in the risk for HIV acquisition. ^[24]

While these data are certainly provocative, given how often the patients were engaging in sexual activity, the number of pills taken averages around three pills per week, making it difficult to fully endorse the practice of on-demand PrEP in all patients.

Although most data cited above concerns adults, trial data assessing the safety and feasibility of PrEP in adolescent MSM aged 15-17 years were published in 2017. ^[25] In this study, 78 patients were enrolled using selection criteria similar to that used for initiating PrEP in adults and were given daily TDF/FTC. Forty-six patients (64%) completed 48 weeks of follow-up. Most participants had detectable levels of the study drug. High levels of tenofovir, consistent with reception of four or more doses per week, which is considered highly protective against HIV acquisition, were detected in 54% at Week 4, 47% at Week 8, 49% at Week 12, 28% at Week 24, 17% at Week 36, and 22% at Week 48. The study demonstrated that PrEP is feasible and safe in this patient population, although adherence seemed to decrease over time. This may justify more frequent follow-up than is expected in adults to provide more effective care and to ensure appropriate adherence and protection.

Potential Concerns for Preexposure Prophylaxis

Drug resistance

A major concern regarding the use of PrEP is the possibility of acquired drug resistance if HIV infection is transmitted. The genetic barrier to resistance for tenofovir is high but low with emtricitabine. The iPrEx trial that evaluated chemoprophylaxis in men who have sex with men (MSM), did not show any incident tenofovir resistance. However, with a poor adherence level among patients in the intervention arm, the possibility is not eliminated. ^[20] Emergence of drug resistance could be a potential problem in the future with more widespread use of antiretrovirals for prophylaxis, although such concerns have yet to come to fruition.

HIV transmissions have been reported among a handful of patients taking effective PrEP regimens. These have mostly involved transmission of HIV with multiclass–drug-resistance mutations, ^[26] reinforcing the need for ongoing condom use in patients who are taking PrEP.

Behavioral changes

A possibility exists that offering PrEP may encourage increased high-risk sexual activity and disinhibition. Recent data have shown an increase in condomless sex among patients taking PrEP, raising concern for transmission of STIs. ^[27] More studies are evaluating the effect of these changes in behavior.

Individuals at high risk

When considering emtricitabine/tenofovir for PrEP it is important to identify individuals at high risk. High-risk patients include those who have partner(s) known to be HIV-1 infected, or who engage in sexual activity within a high prevalence area or social network and exhibit one or more of the following: inconsistent or no condom use, diagnosis of sexually transmitted infections, exchange of sex for commodities (such as money, food, shelter, or drugs), use of illicit drugs or alcohol dependence, or incarceration partner(s) of unknown HIV-1 status with any of the factors listed above.

Patient education and monitoring

When prescribing emtricitabine/tenofovir for PrEP, healthcare providers must ^[28] :

• Prescribe emtricitabine/tenofovir as part of a comprehensive prevention strategy because this drug combination is not always effective in preventing the acquisition of HIV-1 infection.
• Counsel all uninfected individuals to strictly adhere to the recommended emtricitabine/tenofovir dosing schedule because the effectiveness of Truvada in reducing the risk of acquiring HIV-1 was strongly correlated with adherence as demonstrated by measurable drug levels in clinical trials.
• Confirm a negative HIV-1 test immediately prior to initiating emtricitabine/tenofovir for a PrEP indication. If clinical symptoms consistent with acute viral infection are present and recent (< 1 month) exposures are suspected, delay starting PrEP for at least 1 month and reconfirm HIV-1 status or use a test approved by the FDA as an aid in the diagnosis of HIV-1 infection, including acute or primary HIV-1 infection.

CDC Guidelines and Evaluation for Preexposure Prophylaxis

The CDC first issued guidelines for preexposure prophylaxis (PrEP) in May 2014. These were updated in 2017 to incorporate the growing body of data. ^[29] Daily oral PrEP with the fixed-dose combination of tenofovir disoproxil fumarate (TDF) 300 mg and emtricitabine (FTC) 200 mg (Truvada) has been shown to be safe and effective in reducing the risk for sexual HIV acquisition in adults and adolescents weighing at least 35 kg. Daily emtricitabine/tenofovir is one prevention option that is part of the general guidelines for HIV prevention.

In October 2019, the FDA approved the fixed-dose combination of tenofovir alafenamide (TAF) 25 mg plus FTC 200 mg (Descovy) for at-risk adults and adolescents for HIV-1 pre-exposure prophylaxis (PrEP) to reduce the risk for HIV-1 infection from sex, excluding those who have receptive vaginal sex. ^[8]

In 2021, the CDC updated the guideline for preexposure prophylaxis for the prevention of HIV infection. ^[30]  

Three FDA-approved PrEP medications are available:

Two comprise a combination of drugs in one oral tablet taken daily. The third is an injectable medication given every 2 months. They are approved to prevent HIV in adults and adolescents weighing at least 77 lb (35 kg).

• Emtricitabine (F) 200 mg combined with tenofovir disoproxil fumarate (TDF) 300 mg (F/TDF—brand name Truvada® or generic equivalent). Daily oral PrEP with F/TDF is recommended for prevention of HIV among all individuals with sex or injection drug use risk factors.
• Emtricitabine (F) 200 mg combined with tenofovir alafenamide (TAF) 25 mg (F/TAF—brand name Descovy®). Daily oral PrEP with F/TAF is recommended for prevention of HIV through sexual transmission, excluding individuals likely to get HIV through receptive vaginal sex. F/TAF has not been studied for HIV prevention for individuals assigned female at birth who could get HIV through receptive vaginal sex.
• Cabotegravir (CAB) 600 mg injection (brand name Apretude®). Injectable PrEP with CAB is recommended to prevent sexual transmission of HIV among all people. CAB is given as an intramuscular injection. CAB for PrEP is started by giving the first injection followed by a second injection 1 month after the first. CAB injections are administered every 2 months thereafter.

The guidelines apply to the following specific populations:

• Sexually-active adult men who have sex with men (MSM) who are at substantial risk for HIV acquisition; evidence level IA
• Adult heterosexually active men and women who are at substantial risk of HIV acquisition; evidence level IA
• Adult injection drug users (IDUs) at substantial risk of HIV acquisition; evidence level IA
• Heterosexually-active women and men whose partners are known to have HIV infection (HIV-discordant couples); PrEP should be discussed with this population as one of several options to protect the uninfected partner during conception and pregnancy so that an informed decision can be made in awareness of what is known and unknown about benefits and risks of PrEP for mother and fetus; evidence level IIB

PrEP treatment guidelines include:

• Information about PrEP should be provided to all sexually active adults and adolescents.
• For both men and women, PrEP with daily F/TDF is recommended for HIV prevention for sexually-active adults and adolescents who weigh at least 35 kg (77 lb) who report sexual behaviors that place them at substantial ongoing risk for HIV exposure and acquisition.
• For both men and women, PrEP with daily F/TDF is recommended for HIV prevention for adults and adolescents weighing at least 35 kg (77 lb) who inject drugs (PWID) (also referred to as injection drug users [IDU]) and report injection practices that place them at substantial ongoing risk for HIV exposure and acquisition.
• For men only, daily oral PrEP with F/TAF is a recommended option for HIV prevention for sexually active adults and adolescents weighing at least 35 kg (77 lb) who report sexual behaviors that place them at substantial ongoing risk for HIV exposure and acquisition. PrEP with F/TAF has not yet been studied in women (persons assigned female sex at birth whose gender identify is female) and so F/TAF is not recommended for HIV prevention for women or other persons at risk through receptive vaginal sex.
• For transgender women (persons assigned male sex at birth whose gender identity is female) who have sex with men, and who report sexual behaviors that place them at substantial ongoing risk for HIV exposure and acquisition, daily oral PrEP with F/TAF is a recommended option for HIV prevention.
• The efficacy and safety of other daily oral antiretroviral medications for PrEP, either in place of, or in addition to, F/TDF or F/TAF, have not been studied extensively and are not recommended.

Renal function should be assessed by estimated creatinine clearance (eCrCl) at baseline for PrEP patients taking daily oral F/TDF or F/TAF, and monitored periodically so that persons in whom clinically significantrenal dysfunction is developing do not continue to take it.

• Estimated creatinine clearance (eCrCl) should be assessed every 6 months for patients older than 50 years or those who have an eCrCl < 90 ml/min at initiation.
• For all other daily oral PrEP patients, eCrCl should be assessed at least every 12 months.

PrEP with intramuscular cabotegravir (CAB) injections is recommended for HIV prevention in adults and adolescents who report sexual behaviors that place them at substantial ongoing risk for HIV exposure and acquisition.

Acute and chronic HIV infection must be excluded by symptom history and HIV testing immediately before any PrEP regimen is prescribed.

HIV infection should be assessed at least every 3 months for patients taking daily oral PrEP, and every 2 months for patients receiving CAB injections for PrEP so that persons with incident infection do not continue taking it. The 2-drug regimens of F/TDF or F/TAF and the single drug CAB are inadequate therapy for established HIV infection, and their use in persons with early HIV infection may engender resistance to one or more of the PrEP medications.

When PrEP is prescribed, clinicians should provide access, directly or by facilitated referral, to:

• Support for medication adherence and continuation in follow-up PrEP care, because high medication adherence and persistent use are critical to PrEP effectiveness for prevention of HIV acquisition.
• Additional proven effective risk-reduction services, as indicated by reported HIV exposure-prone behaviors, to enable the use of PrEP in combination with other effective prevention methods to reduce risk for sexual acquisition of STIs or acquisition of bloodborne bacterial and viral infections through injection drug use.

PrEP Guidelines by the British HIV Association (BHIVA)/British Association for Sexual Health and HIV (BASHH)

Guidelines on the use of HIV pre-exposure prophylaxis (PrEP) were released in March 2019 by the British HIV Association (BHIVA)/British Association for Sexual Health and HIV (BASHH). ^[31]

PrEP Recommendations in Men Who Have Sex With Men (MSM)

HIV‐negative MSM who are at an increased risk for HIV acquisition because of condomless anal intercourse in the preceding 6 months and ongoing condomless anal intercourse should be offered daily or on‐demand oral tenofovir disoproxil/emtricitabine (TD‐FTC) as PrEP.

HIV‐negative MSM engaging in condomless anal intercourse with a partner who is HIV-positive should be offered daily or on‐demand oral TD‐FTC as PrEP, unless the partner has been on antiretroviral therapy (ART) for at least 6 months and has a plasma viral load of < 200 copies/mL.

PrEP Recommendations in Heterosexual Individuals

HIV‐negative heterosexual men and women engaging in condomless intercourse with a partner who is HIV-positive should be offered daily oral TD‐FTC as PrEP, unless the partner has been on ART for at least 6 months and has a plasma viral load of < 200 copies/mL.

Heterosexual men and women with ongoing risk factors for HIV acquisition should be offered daily oral TD‐FTC as PrEP on a case‐by‐case basis.

Tenofovir disoproxil fumarate (TDF) alone can be offered to heterosexual men and women if FTC is contraindicated.

PrEP Recommendations in Trans Women

HIV‐negative trans women who are at an increased risk for HIV acquisition through condomless anal intercourse in the preceding 6 months and ongoing condomless intercourse should be offered daily oral TD-FTC as PrEP.

HIV‐negative trans women and trans men engaging in condomless intercourse with a partner who is HIV-positive should be offered daily oral TD‐FTC as PrEP, unless the partner has been on ART for at least 6 months and has a plasma viral load of < 200 copies/mL.

PrEP Recommendations in Young People

HIV‐negative young MSM (aged 15-25 years) who are at an increased risk for HIV acquisition because of condomless anal intercourse in the preceding 6 months and ongoing condomless anal intercourse should be offered daily or on‐demand oral TD‐FTC as PrEP.

HIV‐negative young people engaging in condomless anal intercourse with a partner who is HIV-positive should be offered TD‐FTC as PrEP, unless the partner has been on ART for at least 6 months and has a plasma viral load of < 200 copies/mL.

HIV‐negative young trans women who are at an increased risk for HIV acquisition because of condomless anal intercourse in the preceding 6 months and ongoing condomless anal intercourse should be offered daily oral TD‐FTC as PrEP.

Recommendations for Initiating and Discontinuing PrEP

If anal intercourse represents the HIV acquisition risk, PrEP can be initiated as a double-dose of TD‐FTC taken 2-24 hours before intercourse and continued daily until 48 hours following the last sexual risk.

If PrEP for anal intercourse has been interrupted but less than 7 days have elapsed since the last TD‐FTC dose, PrEP can be re‐initiated with a single dose of TD‐FTC.

If vaginal intercourse represents the risk for HIV acquisition, PrEP should be initiated as a daily regimen 7 days before the likely exposure risk and continued daily for 7 days following the last sexual risk.

Recommendations for Baseline Testing

Baseline HIV testing with a combined antigen/antibody serology test should be performed before PrEP is initiated.

Same‐day PrEP initiation may occur in individuals who have a negative result on a third‐generation or higher blood‐based point‐of‐care test (POCT) on the same day or a negative result on a combined HIV antigen/antibody test within the preceding 4 weeks.

HIV viral load should be considered if a high‐risk exposure has occurred within the preceding 4 weeks.

PrEP should be deferred until an HIV RNA result is available in individuals who report condomless anal intercourse in the preceding 4 weeks and who have symptoms that suggest HIV seroconversion.

Baseline hepatitis B virus (HBV) screening should be performed in individuals with unknown HBV status, and vaccination should be initiated in nonimmune persons.

A specialist in viral hepatitis/coinfection should assess patients with evidence of chronic HBV infection to decide whether to continue or to terminate therapy.

On‐demand PrEP dosing should not be offered to individuals with chronic HBV infection.

MSM and other individuals at risk for hepatitis C virus (HCV) infection should undergo baseline HCV screening.

A full baseline sexually transmitted infection (STI) screen should be performed, including syphilis serology and nucleic acid amplification testing (NAAT) for gonococcal and chlamydial infection at exposure sites (genital, rectal, pharyngeal).

Baseline renal function should be assessed with serum creatinine testing, estimated glomerular filtration rate (eGFR), and urinalysis; PrEP can be initiated while results are pending.

The eGFR should be >60 mL/min/1.73 m² in persons starting TDF. If the eGFR is less than this, PrEP should be considered on a case-by-case basis.

Suboptimal Adherence to PrEP

If fewer than four doses of the daily PrEP regimen are taken per week, it is unlikely to be effective. Despite this, no evidence has shown that four instead of seven doses per week is adequate.

Recommendations for Monitoring During PrEP

Individuals on PrEP should undergo HIV testing every 3 months with a laboratory combined HIV antigen/antibody test or a blood‐based POCT.

Individuals on PrEP with symptoms that suggest HIV seroconversion should undergo combined HIV antigen/antibody testing and HIV viral load testing.

If primary HIV infection is confirmed, baseline resistance testing should be performed to evaluate for evidence of resistance‐associated mutations to tenofovir or emtricitabine, along with other mutations.

All individuals on PrEP should undergo screening for bacterial STIs every 3 months. MSM, trans women, and others with an ongoing HCV risk should also undergo HCV testing every 3 months.

Recommendations for Terminating PrEP

PrEP should be discontinued if an HIV test shows a positive result, and the patient should be immediately referred to an HIV specialist.

Suboptimal adherence to PrEP is a relative contraindication to continued use.

HBV infection should be excluded prior to discontinuing TD‐FTC in patients without vaccine-induced immunity.

US Preventive Services Task Force Recommendation Statement

The US Preventive Services Task Force (USPSTF) issued a statement on August 22, 2023, recommending offering preexposure prophylaxis (PrEP) for HIV infection to persons at increased risk for infection. ^[32]

The PrEP recommendation also means that private insurers will be required to cover the cost of PrEP drugs, according to rules established by the Affordable Care Act.

Individuals at risk of HIV infection include men who have sex with men (MSM), individuals who are at risk because of heterosexual contact, and individuals who inject drugs. Certain risk factors or behaviors can further increase the likelihood of infection.

Risk assessment

MSM who are sexually active and meet at least one of the following criteria should be considered for PrEP:

• Is in a sexual relationship with a partner who has HIV infection
• Reports inconsistent condom use during anal sex (receptive or insertive)
• Has had a sexually transmitted infection (STI; syphilis, gonorrhea, or chlamydia) within the preceding 6 months

Heterosexually active men and women who meet one of the following criteria should be considered for PrEP:

• Is in a sexual relationship with a partner who has HIV infection
• Reports inconsistent condom use during sex with a partner of unknown HIV status who is considered to be at high risk (eg, a man who has sex with men and women or an individual who injects drugs)
• Has had an STI (syphilis or gonorrhea) within the preceding 6 months

Individuals who inject drugs and meet one of the following criteria should be considered for PreP:

• Shares drug injection equipment
• Is at risk of sexual HIV acquisition

Transgender women and individuals who engage in transactional sex (eg, for money, drugs, or housing), including commercial sex workers or persons trafficked for sex work are at high risk for HIV infection. They should also be considerfed for PrEP based on the above criteria.

Preventive medication

Combined tenofovir disoproxil fumarate and emtricitabine administered orally once a day is the only formulation of PrEP that is FDA-approved in the United States for use in persons at risk of sexually transmitted HIV infection.

Awareness and Indications

It is estimated that approximately 25% of MSM and 19% of injection drug users would be eligible for daily PrEP. ^[33] Despite these numbers and some signs of overall progress in engaging eligible patients in care, ^[34] a significant number of at-risk patients remain unware of PrEP availability. This is especially true in some of the most at-risk populations, such as Black MSM. ^[35] Continuing efforts in provider education are paramount for successful implementation of these programs.

Conclusion

The idea of treatment as prevention for HIV-1 infection has gathered tremendous enthusiasm and is driven by a) failure of behavioral and biological prevention efforts; b) biological plausibility of the use of ARV for prevention; c) cheaper, safer, and simpler ART regimens; and d) recent clinical trials that show promise for the intervention.

PrEP has the potential to contribute to effective and safe HIV prevention when 1) it is targeted to individuals at high risk for HIV acquisition; 2) delivered as part of a comprehensive set of prevention services, including risk-reduction and PrEP medication adherence counseling, ready access to condoms, and diagnosis and treatment of sexually transmitted infections; 3) and it is accompanied by monitoring of HIV status, side effects, adherence, and risk behaviors at regular intervals.

The FDA approval of emtricitabine/tenofovir (Truvada) for PrEP now offers options to high-risk groups including men who have sex with men and serodiscordant couples. Additionally, current CDC guidelines include additional populations (eg, IV drug users, heterosexual individuals at high risk).

In spite of the promise and the progress of PrEP, concerns about durability of protection, the balance of benefits and adverse events associated with earlier therapy, and long-term adherence and transmission of ART-resistant strains to partners remain. Longer-term studies are needed but should not preclude the implementation of this strategy. As the search for an effective vaccine continues, interventions like PrEP could significantly slow the HIV epidemic.

References

1. WHO. HIV data and statistics. World Health Organization. Available at https://www.who.int/teams/global-hiv-hepatitis-and-stis-programmes/hiv/strategic-information/hiv-data-and-statistics. 2024; Accessed: April 1, 2025.
2. Cachay ER. Human Immunodeficiency Virus Infection. Porter RE. The Merck Manual of Diagnosis and Therapy. Rahway, NJ: Merck & Co Inc; Reviewed/Revised May 2024 | Modified Jan 2025. [Full Text].
3. Marfatia YS, Jose SK, Baxi RR, Shah RJ. Pre- and post-sexual exposure prophylaxis of HIV: An update. Indian J Sex Transm Dis AIDS. 2017 Jan-Jun. 38 (1):1-9. [QxMD MEDLINE Link]. [Full Text].
4. Koester KA, Erguera XA, Udoh Efioma, Dufour MSK, Burack J, Myers JJ. Exploring the Shift From HIV Pre-exposure Prophylaxis Awareness to Uptake Among Young Gay and Bisexual Men. Front Public Health. 2021 December. 7;9:677716:[Full Text].
5. HIV.gov. Pre-Exposure Prophylaxis. HIV.gov. Available at https://www.hiv.gov/hiv-basics/hiv-prevention/using-hiv-medication-to-reduce-risk/pre-exposure-prophylaxis. February 7, 2025; Accessed: April 1, 2025.
6. Cohen MS, Gay CL. Treatment to prevent transmission of HIV-1. Clin Infect Dis. 2010 May 15. 50 Suppl 3:S85-95. [QxMD MEDLINE Link].
7. Dumond JB, Yeh RF, Patterson KB, Corbett AH, Jung BH, Rezk NL, et al. Antiretroviral drug exposure in the female genital tract: implications for oral pre- and post-exposure prophylaxis. AIDS. 2007 Sep 12. 21(14):1899-907. [QxMD MEDLINE Link]. [Full Text].
8. Descovy (emtricitabine/tenofovir AF) [package insert]. Foster City, CA: Gilead Sciences. October, 2019. Available at [Full Text].
9. D’Angelo AB, Westmoreland DA, Carneiro PB, Johnson J, Grov C. Why Are Patients Switching from Tenofovir Disoproxil Fumarate/Emtricitabine (Truvada) to Tenofovir Alafenamide/Emtricitabine (Descovy) for Pre-Exposure Prophylaxis?. AIDS Patient Care STDS. 2021 Aug. 35 (8):327-334. [QxMD MEDLINE Link]. [Full Text].
10. Graham SM, Holte SE, Peshu NM, Richardson BA, Panteleeff DD, Jaoko WG. Initiation of antiretroviral therapy leads to a rapid decline in cervical and vaginal HIV-1 shedding. AIDS. 2007 Feb 19. 21(4):501-7. [QxMD MEDLINE Link].
11. Reynolds SJ, Makumbi F, Nakigozi G, Kagaayi J, Gray RH, Wawer M, et al. HIV-1 transmission among HIV-1 discordant couples before and after the introduction of antiretroviral therapy. AIDS. 2011 Feb 20. 25(4):473-7. [QxMD MEDLINE Link].
12. Cohen MS, Chen YQ, McCauley M, Gamble T, Hosseinipour MC, Kumarasamy N, et al. Prevention of HIV-1 infection with early antiretroviral therapy. N Engl J Med. 2011 Aug 11. 365(6):493-505. [QxMD MEDLINE Link]. [Full Text].
13. Donnell D, Baeten JM, Kiarie J, Thomas KK, Stevens W, Cohen CR, et al. Heterosexual HIV-1 transmission after initiation of antiretroviral therapy: a prospective cohort analysis. Lancet. 2010 Jun 12. 375(9731):2092-8. [QxMD MEDLINE Link]. [Full Text].
14. Das M, Chu PL, Santos GM, Scheer S, Vittinghoff E, McFarland W, et al. Decreases in community viral load are accompanied by reductions in new HIV infections in San Francisco. PLoS One. 2010 Jun 10. 5(6):e11068. [QxMD MEDLINE Link]. [Full Text].
15. Montaner JS, Lima VD, Barrios R, Yip B, Wood E, Kerr T, et al. Association of highly active antiretroviral therapy coverage, population viral load, and yearly new HIV diagnoses in British Columbia, Canada: a population-based study. Lancet. 2010 Aug 14. 376(9740):532-9. [QxMD MEDLINE Link]. [Full Text].
16. Anglemyer A, Rutherford GW, Baggaley RC, Egger M, Siegfried N. Antiretroviral therapy for prevention of HIV transmission in HIV-discordant couples. Cochrane Database Syst Rev. 2011 Aug 10. CD009153. [QxMD MEDLINE Link].
17. Cohen MS, Chen YQ, McCauley M, Gamble T, Hosseinipour MC. Antiretroviral Therapy for the Prevention of HIV-1 Transmission. N Engl J Med. 2016 Sep 1. 375 (9):830-9. [QxMD MEDLINE Link].
18. Erlwanger A, Rocroi I, Kirtley S, Hemelaar J. Perinatal outcomes associated with pre-exposure prophylaxis for HIV prevention during pregnancy: a systematic review and meta-analysis. EClinicalMedicine. 2024 Apr. 70:102532. [QxMD MEDLINE Link]. [Full Text].
19. Landovitz RJ, Donnell D, Clement ME, and the, HPTN 083 Study Team. Cabotegravir for HIV Prevention in Cisgender Men and Transgender Women. N Engl J Med. 2021 Aug 12. 385 (7):595-608. [QxMD MEDLINE Link].
20. Grant RM, Lama JR, Anderson PL, McMahan V, Liu AY, Vargas L, et al. Preexposure chemoprophylaxis for HIV prevention in men who have sex with men. N Engl J Med. 2010 Dec 30. 363(27):2587-99. [QxMD MEDLINE Link]. [Full Text].
21. Baeten JM, Donnell D, Ndase P, Mugo NR, Campbell JD, Wangisi J, et al. Antiretroviral prophylaxis for HIV prevention in heterosexual men and women. N Engl J Med. 2012 Aug 2. 367(5):399-410. [QxMD MEDLINE Link].
22. Choopanya K, Martin M, Suntharasam P, Sangkum U, Mock P, Leethochawalit M, et al. Antiretroviral prophylaxis for HIV infection in injecting drug users in Bangkok, Thailand (the Bangkok Tenofovir Study): a randomized, double-blind, placebo-controlled phase 3 trial. Lancet. 2013. 2083-90.
23. McCormack S, Dunn DT, Desai M, Dolling DI, Gafos M,. Pre-exposure prophylaxis to prevent the acquisition of HIV-1 infection (PROUD): effectiveness results from the pilot phase of a pragmatic open-label randomised trial. Lancet. 2016 Jan 2. 387 (10013):53-60. [QxMD MEDLINE Link].
24. Molina JM, Capitant C, Spire B, Pialoux G,. On-Demand Preexposure Prophylaxis in Men at High Risk for HIV-1 Infection. N Engl J Med. 2015 Dec 3. 373 (23):2237-46. [QxMD MEDLINE Link].
25. Hosek SG, Landovitz RJ, Kapogiannis B, Siberry GK, Rudy B, Rutledge B, et al. Safety and Feasibility of Antiretroviral Preexposure Prophylaxis for Adolescent Men Who Have Sex With Men Aged 15 to 17 Years in the United States. JAMA Pediatr. 2017 Nov 1. 171 (11):1063-1071. [QxMD MEDLINE Link].
26. Knox DC, Anderson PL, Harrigan PR, Tan DH. Multidrug-Resistant HIV-1 Infection despite Preexposure Prophylaxis. N Engl J Med. 2017 Feb 2. 376 (5):501-502. [QxMD MEDLINE Link].
27. Oldenburg CE, Nunn AS, Montgomery M, Almonte A, Mena L, Patel RR, et al. Behavioral Changes Following Uptake of HIV Pre-exposure Prophylaxis Among Men Who Have Sex with Men in a Clinical Setting. AIDS Behav. 2018 Apr. 22 (4):1075-1079. [QxMD MEDLINE Link].
28. [Guideline] CDC. Clinical Guidance for PrEP. US Centers for Disease Control and Prevention. Available at https://www.cdc.gov/hivnexus/hcp/prep/index.html. February 10, 2025; Accessed: April 1, 2025.
29. [Guideline] U.S. Public Health Service, Center for Disease Control and Prevention (CDC). Preexposure prophylaxis for the prevention of HIV infection in the United States – Updated 2017. Available at https://www.cdc.gov/hiv/pdf/risk/prep/cdc-hiv-prep-guidelines-2017.pdf. 2017; Accessed: 2019 Oct 04.
30. [Guideline] Preexposure Prophylaxis (PrEP). CDC. Available at https://www.cdc.gov/hiv/clinicians/prevention/prep.html. 2021 Dec 20; Accessed: December 22, 2021.
31. [Guideline] BHIVA/BASHH guidelines on the use of HIV pre-exposure prophylaxis (PrEP) 2018. HIV Med. 2019 Mar. 20 Suppl 2:s2-s80. [QxMD MEDLINE Link].
32. [Guideline] US Preventive Services Task Force, Barry MJ, Nicholson WK, Silverstein M, Chelmow D, Coker TR, et al. Preexposure Prophylaxis to Prevent Acquisition of HIV: US Preventive Services Task Force Recommendation Statement. JAMA. 2023 Aug 22. 330 (8):736-745. [QxMD MEDLINE Link]. [Full Text].
33. Smith DK, Van Handel M, Wolitski RJ, Stryker JE, Hall HI, Prejean J, et al. Vital Signs: Estimated Percentages and Numbers of Adults with Indications for Preexposure Prophylaxis to Prevent HIV Acquisition–United States, 2015. MMWR Morb Mortal Wkly Rep. 2015 Nov 27. 64 (46):1291-5. [QxMD MEDLINE Link].
34. Laufer FN, O’Connell DA, Feldman I, MPS., Zucker HA. Vital Signs: Increased Medicaid Prescriptions for Preexposure Prophylaxis Against HIV infection–New York, 2012-2015. MMWR Morb Mortal Wkly Rep. 2015 Nov 27. 64 (46):1296-301. [QxMD MEDLINE Link].
35. Eaton LA, Driffin DD, Bauermeister J, Smith H, Conway-Washington C. Minimal Awareness and Stalled Uptake of Pre-Exposure Prophylaxis (PrEP) Among at Risk, HIV-Negative, Black Men Who Have Sex with Men. AIDS Patient Care STDS. 2015 Aug. 29 (8):423-9. [QxMD MEDLINE Link].