HIV临床试验市场－全球产业规模、份额、趋势、机会、预测：按阶段、研究设计、申办者、地区和竞争对手划分，2021-2031年

全球 HIV 临床试验市场预计将从 2025 年的 16.7 亿美元成长到 2031 年的 23.2 亿美元，复合年增长率为 5.63%。

这些试验包括旨在评估用于治疗或预防人类免疫力缺乏病毒（HIV）的药物和行为干预措施的安全性和有效性的系统性研究。该市场的主要驱动力是HIV感染在全球范围内的持续蔓延，这使得开发创新抗逆转录病毒疗法和有效疫苗的需求持续存在。全球卫生组织和政府机构为实现病毒抑制目标提供了大量资金支持，从而推动了这项需求。根据联合国爱滋病规划署（UNAIDS）2024年的报告，全球约有4,080万人感染HIV，凸显了持续推动治疗方法和提供可近性治疗方案的重要性。

然而，在医疗基础设施不足的地区，我们在招募和留住病患方面面临巨大的挑战。确保参与者长期持续参与的后勤难题常常导致营运延误和成本增加。这些问题会阻碍关键临床试验的顺利进行，并成为开发重要新治疗方法的障碍。

市场驱动因素

长效注射抗逆转录病毒疗法的研发正在改变该领域的格局，解决了每日口服药物带来的许多挑战。製药公司正积极优先研发缓释製剂，以提供更便利的给药方案，进而提高临床试验和真实世界研究中的病患遵从率。吉利德科学公司于2024年7月宣布“吉利德在研的每年两次给药的瑞那卡帕韦（Renacapavir）的完整疗效和安全性结果”，这是该领域的一项重大进展。在3期PURPOSE 1试验中，瑞那卡帕韦对未确诊感染的顺性别女性显示100%的疗效。这种降低给药频率的措施不仅有助于改善治疗效果，而且随着竞争对手致力于研发给药间隔长达数月的製剂，也为临床研发注入了新的活力。

同时，人们也正致力于功能性修復和基因疗法的研究，以实现持续的病毒抑制。该研究倡议重点关注广谱中和抗体等创新方法，并获得了早期通讯协定的大力资助。如同治疗行动小组（TAG）于2024年7月发布的《2024年研发管线报告》所述，随着艾伯维公司启动其II期临床试验（140名受试者），研究范围正在扩大。该试验将是迄今为止规模最大的HIV治疗相关介入试验，并设有分析性治疗终止期。儘管取得了这些科学进展，但持续高企的感染率凸显了这些研究的重要性。根据联合国爱滋病规划署的数据，2024年全球将新增约130万HIV感染者，这再次表明，在预防和治疗方面的临床研究需要不断创新。

市场挑战

全球爱滋病临床试验市场面临的一大障碍是医疗基础设施不足地区招募和留住病患的难度。进行严谨的研究需要配备可靠的医疗设备、稳定的供应链和训练有素的医护人员，以确保资料的完整性和受试者的安全。然而，在许多爱滋病感染率高的地区，这些基本要素往往缺失或无法可靠保障。基础设施的匮乏使得试验管理困难重重，导致受试者脱落率增加和研究週期延长。因此，製药公司面临营运成本增加和新治疗方法上市时间显着延迟的双重困境，这直接阻碍了该行业的成长潜力。

造成这种营运不稳定的根本原因在于资源严重匮乏，阻碍了关键基础设施的发展。 2024年，联合国爱滋病规划署（UNAIDS）报告称，在低收入和中等收入国家，有效控制爱滋病所需的资金筹措目标金额与实际筹集到的爱滋病防治资金之间存在约95亿美元的缺口。这一资金缺口限制了当地医疗卫生系统满足临床研究高要求的能力。除非投入足够的资金来加强这些医疗卫生系统，否则市场在进行开发下一代爱滋病治疗方法所需的大规模、多样化试验方面将继续面临挑战。

市场趋势

在患者分层和保留方面应用人工智慧 (AI) 正成为解决该领域参与者管理长期低效问题的关键趋势。随着复杂的机器学习演算法越来越多地用于分析海量资料集，研究人员能够以惊人的准确度预测患者的用药依从性模式并优化队列选择。这种技术整合有助于及早识别高风险族群，从而直接降低长期研究中常见的较高脱落率。美国国立卫生Meta分析(NIH) 在 2025 年 2 月发布的综述《人工智慧在 HIV 研究中的应用：进展与未来方向》中重点介绍了一项对 401,389 名 HIV 感染者进行的荟萃分析，该分析表明这些模型具有显着提高大规模临床试验决策和预测准确性的潜力。

同时，市场显然优先考虑儿童和青少年製剂的临床试验，旨在弥合先前被排除在基础研究之外的年轻一代在治疗选择方面的差距。投资者和相关人员正集中资金开发适合不同年龄层的干预措施，例如针对正在发育的免疫系统量身定制的疫苗和缓释疗法。这一趋势源于迫切需要为需要终身管理计划的婴儿童提供公平的医疗保健标准。根据威尔康奈尔医学院2025年9月发布的题为「美国国立卫生研究院津贴旨在开发儿童HIV疫苗」的新闻稿，一个多机构研究小组已获得2080万美元的津贴，用于推进一种专门为儿童临床试验设计的实验性HIV疫苗的临床前开发和完善工作。

目录

第一章概述

第二章：调查方法

第三章执行摘要

第四章：客户心声

第五章：全球爱滋病临床试验市场展望

• 市场规模及预测
  • 按金额
• 市占率及预测
  • 阶段（第一阶段、第二阶段、第三阶段、第四阶段）
  • 依研究设计进行的研究（介入研究、观察性研究、扩大使用研究）
  • 赞助商（製药和生物製药公司、非营利组织、其他）
  • 按地区
  • 按公司（2025 年）
• 市场地图

第六章：北美爱滋病临床试验市场展望

• 市场规模及预测
• 市占率及预测
• 北美洲：国别分析
  • 我们
  • 加拿大
  • 墨西哥

第七章：欧洲爱滋病临床试验市场展望

• 市场规模及预测
• 市占率及预测
• 欧洲：国别分析
  • 德国
  • 法国
  • 英国
  • 义大利
  • 西班牙

第八章：亚太地区爱滋病临床试验市场展望

• 市场规模及预测
• 市占率及预测
• 亚太地区：国别分析
  • 中国
  • 印度
  • 日本
  • 韩国
  • 澳洲

第九章：中东和非洲爱滋病临床试验市场展望

• 市场规模及预测
• 市占率及预测
• 中东与非洲：国别分析
  • 沙乌地阿拉伯
  • 阿拉伯聯合大公国
  • 南非

第十章：南美洲爱滋病临床试验市场展望

• 市场规模及预测
• 市占率及预测
• 南美洲：国别分析
  • 巴西
  • 哥伦比亚
  • 阿根廷

第十一章 市场动态

• 促进因素
• 任务

第十二章 市场趋势与发展

• 併购
• 产品发布
• 近期趋势

第十三章：全球爱滋病临床试验市场：SWOT分析

第十四章：波特五力分析

• 产业竞争
• 新进入者的潜力
• 供应商的议价能力
• 顾客权力
• 替代品的威胁

第十五章 竞争格局

• PPD Inc
• IQVIA Inc
• PAREXEL International Corp
• ICON PLC
• Syneos Health Inc
• WuXi AppTec Co Ltd
• Janssen Global Services LLC
• Gilead Sciences Inc
• GSK PLC
• Charles River Laboratories Inc

第十六章 策略建议

第十七章：关于研究公司及免责声明

The Global HIV Clinical Trials Market is projected to expand from USD 1.67 Billion in 2025 to USD 2.32 Billion by 2031, registering a CAGR of 5.63%. These trials involve systematic research aimed at assessing the safety and effectiveness of pharmaceutical and behavioral interventions designed to treat or prevent the Human Immunodeficiency Virus. The primary driver for this market is the enduring global prevalence of the infection, which creates a continuous need for innovative antiretroviral therapies and the development of viable vaccines. This demand is supported by significant financial backing from international health organizations and government bodies striving to reach viral suppression goals. As reported by UNAIDS in 2024, roughly 40.8 million individuals were living with HIV worldwide, highlighting the vital necessity for ongoing therapeutic progress and accessible treatment solutions.

However, the industry faces substantial hurdles related to the difficulties of recruiting and retaining patients in areas with inadequate healthcare infrastructure. The logistical challenges involved in ensuring consistent participant engagement over long durations frequently result in operational setbacks and escalating costs. These issues can hinder the efficient advancement of critical clinical studies, posing a barrier to the timely development of essential new interventions.

Market Driver

The landscape of the sector is being transformed by the creation of long-acting injectable antiretroviral therapies, which solve key issues related to adhering to daily oral medication. Pharmaceutical firms are actively prioritizing extended-release options that provide more convenient dosing schedules, which in turn boosts patient retention in both clinical trials and actual treatment settings. A significant breakthrough in this area was highlighted in a July 2024 press release by Gilead Sciences regarding the 'Full Efficacy and Safety Results for Gilead Investigational Twice-Yearly Lenacapavir'; the Phase 3 PURPOSE 1 trial showed that lenacapavir reached 100% efficacy with no infections found among cisgender women. This move toward less frequent dosing not only improves treatment results but also energizes the clinical pipeline as rivals work to create formulations with dosing gaps of several months.

At the same time, there is a heightened focus on investigating functional cures and gene therapies aimed at achieving sustained viral remission. Research initiatives are increasingly centering on innovative approaches like broadly neutralizing antibodies, backed by strong funding for early-stage protocols. As noted by the Treatment Action Group in their '2024 Pipeline Report' from July 2024, the research field has broadened with the start of an AbbVie Phase II study enrolling 140 participants, marking it as the largest HIV cure-related interventional trial to date involving analytical treatment interruption. Even with these scientific advances, the ongoing transmission rates emphasize the critical need for such studies; UNAIDS reported that in 2024, about 1.3 million people were newly infected with HIV worldwide, confirming the necessity for persistent innovation in preventative and curative clinical research.

Market Challenge

A major obstacle facing the Global HIV Clinical Trials Market is the difficulty of recruiting and retaining patients in regions with insufficient healthcare infrastructure. Performing rigorous studies necessitates sites equipped with dependable medical tools, steady supply chains, and skilled staff to guarantee data integrity and participant safety. However, in many areas with high HIV prevalence, these essential components are often missing or inconsistent. This infrastructure deficit makes the logistical handling of trials more difficult, resulting in high rates of participant dropout and prolonged study durations. As a result, pharmaceutical companies encounter higher operational expenses and substantial delays in introducing new therapies, which directly impedes the growth potential of the sector.

Severe resource limitations that hinder essential infrastructural improvements are the root cause of this operational instability. UNAIDS reported in 2024 that there was a funding gap of approximately USD 9.5 billion between the available resources for HIV responses in low- and middle-income nations and the targets needed for effective disease management. This lack of funds restricts the capacity of local health systems to meet the rigorous demands of clinical research. Unless there is sufficient investment to strengthen these healthcare structures, the market will continue to face challenges in conducting the large-scale, diverse trials required to develop the next generation of HIV treatments.

Market Trends

The use of Artificial Intelligence for patient stratification and retention is becoming a pivotal trend, tackling long-standing inefficiencies in managing participants within the sector. Sophisticated machine learning algorithms are increasingly utilized to examine immense datasets, allowing researchers to forecast patient adherence patterns and refine cohort selection with remarkable accuracy. This integration of technology directly helps reduce the high dropout rates typical of long-term studies by detecting at-risk individuals early on. As highlighted in a February 2025 review by the National Institutes of Health titled 'AI applications in HIV research: advances and future directions', a meta-analysis of 401,389 people living with HIV showed that these models have the potential to vastly improve clinical decision-making and predictive precision in large-scale trials.

At the same time, the market is seeing a clear emphasis on trials for pediatric and adolescent-specific formulations, aiming to bridge the therapeutic gap for younger groups that have historically been left out of primary research. Investors and stakeholders are channeling more funds into creating age-appropriate interventions, including vaccines and long-acting treatments customized for developing immune systems. This trend is motivated by the critical necessity of offering equitable standards of care for infants and children needing lifelong management plans. According to a September 2025 news release from Weill Cornell Medicine regarding the 'NIH Grant Aims for Childhood Vaccine Against HIV', a multi-institutional group received a $20.8 million grant to further the preclinical development and refinement of an experimental HIV vaccine tailored specifically for pediatric clinical trials.

Key Market Players

• PPD Inc
• IQVIA Inc
• PAREXEL International Corp
• ICON PLC
• Syneos Health Inc
• WuXi AppTec Co Ltd
• Janssen Global Services LLC
• Gilead Sciences Inc
• GSK PLC
• Charles River Laboratories Inc

Report Scope

In this report, the Global HIV Clinical Trials Market has been segmented into the following categories, in addition to the industry trends which have also been detailed below:

HIV Clinical Trials Market, By Phase

• Phase I
• Phase II
• Phase III
• Phase IV

HIV Clinical Trials Market, By Study Design

• Interventional Studies
• Observational Studies
• Expanded Access Studies

HIV Clinical Trials Market, By Sponsor

• Pharmaceutical & Biopharmaceutical Companies
• Non-Profit Organizations
• Others

HIV Clinical Trials Market, By Region

• North America
  • United States
  • Canada
  • Mexico
• Europe
  • France
  • United Kingdom
  • Italy
  • Germany
  • Spain
• Asia Pacific
  • China
  • India
  • Japan
  • Australia
  • South Korea
• South America
  • Brazil
  • Argentina
  • Colombia
• Middle East & Africa
  • South Africa
  • Saudi Arabia
  • UAE

Competitive Landscape

Company Profiles: Detailed analysis of the major companies present in the Global HIV Clinical Trials Market.

Available Customizations:

Global HIV Clinical Trials Market report with the given market data, TechSci Research offers customizations according to a company's specific needs. The following customization options are available for the report:

Company Information

• Detailed analysis and profiling of additional market players (up to five).

Table of Contents

1. Product Overview

• 1.1. Market Definition
• 1.2. Scope of the Market
  • 1.2.1. Markets Covered
  • 1.2.2. Years Considered for Study
  • 1.2.3. Key Market Segmentations

2. Research Methodology

• 2.1. Objective of the Study
• 2.2. Baseline Methodology
• 2.3. Key Industry Partners
• 2.4. Major Association and Secondary Sources
• 2.5. Forecasting Methodology
• 2.6. Data Triangulation & Validation
• 2.7. Assumptions and Limitations

3. Executive Summary

• 3.1. Overview of the Market
• 3.2. Overview of Key Market Segmentations
• 3.3. Overview of Key Market Players
• 3.4. Overview of Key Regions/Countries
• 3.5. Overview of Market Drivers, Challenges, Trends

4. Voice of Customer

5. Global HIV Clinical Trials Market Outlook

• 5.1. Market Size & Forecast
  • 5.1.1. By Value
• 5.2. Market Share & Forecast
  • 5.2.1. By Phase (Phase I, Phase II, Phase III, Phase IV)
  • 5.2.2. By Study Design (Interventional Studies, Observational Studies, Expanded Access Studies)
  • 5.2.3. By Sponsor (Pharmaceutical & Biopharmaceutical Companies, Non-Profit Organizations, Others)
  • 5.2.4. By Region
  • 5.2.5. By Company (2025)
• 5.3. Market Map

6. North America HIV Clinical Trials Market Outlook

• 6.1. Market Size & Forecast
  • 6.1.1. By Value
• 6.2. Market Share & Forecast
  • 6.2.1. By Phase
  • 6.2.2. By Study Design
  • 6.2.3. By Sponsor
  • 6.2.4. By Country
• 6.3. North America: Country Analysis
  • 6.3.1. United States HIV Clinical Trials Market Outlook
    • 6.3.1.1. Market Size & Forecast
      • 6.3.1.1.1. By Value
    • 6.3.1.2. Market Share & Forecast
      • 6.3.1.2.1. By Phase
      • 6.3.1.2.2. By Study Design
      • 6.3.1.2.3. By Sponsor
  • 6.3.2. Canada HIV Clinical Trials Market Outlook
    • 6.3.2.1. Market Size & Forecast
      • 6.3.2.1.1. By Value
    • 6.3.2.2. Market Share & Forecast
      • 6.3.2.2.1. By Phase
      • 6.3.2.2.2. By Study Design
      • 6.3.2.2.3. By Sponsor
  • 6.3.3. Mexico HIV Clinical Trials Market Outlook
    • 6.3.3.1. Market Size & Forecast
      • 6.3.3.1.1. By Value
    • 6.3.3.2. Market Share & Forecast
      • 6.3.3.2.1. By Phase
      • 6.3.3.2.2. By Study Design
      • 6.3.3.2.3. By Sponsor

7. Europe HIV Clinical Trials Market Outlook

• 7.1. Market Size & Forecast
  • 7.1.1. By Value
• 7.2. Market Share & Forecast
  • 7.2.1. By Phase
  • 7.2.2. By Study Design
  • 7.2.3. By Sponsor
  • 7.2.4. By Country
• 7.3. Europe: Country Analysis
  • 7.3.1. Germany HIV Clinical Trials Market Outlook
    • 7.3.1.1. Market Size & Forecast
      • 7.3.1.1.1. By Value
    • 7.3.1.2. Market Share & Forecast
      • 7.3.1.2.1. By Phase
      • 7.3.1.2.2. By Study Design
      • 7.3.1.2.3. By Sponsor
  • 7.3.2. France HIV Clinical Trials Market Outlook
    • 7.3.2.1. Market Size & Forecast
      • 7.3.2.1.1. By Value
    • 7.3.2.2. Market Share & Forecast
      • 7.3.2.2.1. By Phase
      • 7.3.2.2.2. By Study Design
      • 7.3.2.2.3. By Sponsor
  • 7.3.3. United Kingdom HIV Clinical Trials Market Outlook
    • 7.3.3.1. Market Size & Forecast
      • 7.3.3.1.1. By Value
    • 7.3.3.2. Market Share & Forecast
      • 7.3.3.2.1. By Phase
      • 7.3.3.2.2. By Study Design
      • 7.3.3.2.3. By Sponsor
  • 7.3.4. Italy HIV Clinical Trials Market Outlook
    • 7.3.4.1. Market Size & Forecast
      • 7.3.4.1.1. By Value
    • 7.3.4.2. Market Share & Forecast
      • 7.3.4.2.1. By Phase
      • 7.3.4.2.2. By Study Design
      • 7.3.4.2.3. By Sponsor
  • 7.3.5. Spain HIV Clinical Trials Market Outlook
    • 7.3.5.1. Market Size & Forecast
      • 7.3.5.1.1. By Value
    • 7.3.5.2. Market Share & Forecast
      • 7.3.5.2.1. By Phase
      • 7.3.5.2.2. By Study Design
      • 7.3.5.2.3. By Sponsor

8. Asia Pacific HIV Clinical Trials Market Outlook

• 8.1. Market Size & Forecast
  • 8.1.1. By Value
• 8.2. Market Share & Forecast
  • 8.2.1. By Phase
  • 8.2.2. By Study Design
  • 8.2.3. By Sponsor
  • 8.2.4. By Country
• 8.3. Asia Pacific: Country Analysis
  • 8.3.1. China HIV Clinical Trials Market Outlook
    • 8.3.1.1. Market Size & Forecast
      • 8.3.1.1.1. By Value
    • 8.3.1.2. Market Share & Forecast
      • 8.3.1.2.1. By Phase
      • 8.3.1.2.2. By Study Design
      • 8.3.1.2.3. By Sponsor
  • 8.3.2. India HIV Clinical Trials Market Outlook
    • 8.3.2.1. Market Size & Forecast
      • 8.3.2.1.1. By Value
    • 8.3.2.2. Market Share & Forecast
      • 8.3.2.2.1. By Phase
      • 8.3.2.2.2. By Study Design
      • 8.3.2.2.3. By Sponsor
  • 8.3.3. Japan HIV Clinical Trials Market Outlook
    • 8.3.3.1. Market Size & Forecast
      • 8.3.3.1.1. By Value
    • 8.3.3.2. Market Share & Forecast
      • 8.3.3.2.1. By Phase
      • 8.3.3.2.2. By Study Design
      • 8.3.3.2.3. By Sponsor
  • 8.3.4. South Korea HIV Clinical Trials Market Outlook
    • 8.3.4.1. Market Size & Forecast
      • 8.3.4.1.1. By Value
    • 8.3.4.2. Market Share & Forecast
      • 8.3.4.2.1. By Phase
      • 8.3.4.2.2. By Study Design
      • 8.3.4.2.3. By Sponsor
  • 8.3.5. Australia HIV Clinical Trials Market Outlook
    • 8.3.5.1. Market Size & Forecast
      • 8.3.5.1.1. By Value
    • 8.3.5.2. Market Share & Forecast
      • 8.3.5.2.1. By Phase
      • 8.3.5.2.2. By Study Design
      • 8.3.5.2.3. By Sponsor

9. Middle East & Africa HIV Clinical Trials Market Outlook

• 9.1. Market Size & Forecast
  • 9.1.1. By Value
• 9.2. Market Share & Forecast
  • 9.2.1. By Phase
  • 9.2.2. By Study Design
  • 9.2.3. By Sponsor
  • 9.2.4. By Country
• 9.3. Middle East & Africa: Country Analysis
  • 9.3.1. Saudi Arabia HIV Clinical Trials Market Outlook
    • 9.3.1.1. Market Size & Forecast
      • 9.3.1.1.1. By Value
    • 9.3.1.2. Market Share & Forecast
      • 9.3.1.2.1. By Phase
      • 9.3.1.2.2. By Study Design
      • 9.3.1.2.3. By Sponsor
  • 9.3.2. UAE HIV Clinical Trials Market Outlook
    • 9.3.2.1. Market Size & Forecast
      • 9.3.2.1.1. By Value
    • 9.3.2.2. Market Share & Forecast
      • 9.3.2.2.1. By Phase
      • 9.3.2.2.2. By Study Design
      • 9.3.2.2.3. By Sponsor
  • 9.3.3. South Africa HIV Clinical Trials Market Outlook
    • 9.3.3.1. Market Size & Forecast
      • 9.3.3.1.1. By Value
    • 9.3.3.2. Market Share & Forecast
      • 9.3.3.2.1. By Phase
      • 9.3.3.2.2. By Study Design
      • 9.3.3.2.3. By Sponsor

10. South America HIV Clinical Trials Market Outlook

• 10.1. Market Size & Forecast
  • 10.1.1. By Value
• 10.2. Market Share & Forecast
  • 10.2.1. By Phase
  • 10.2.2. By Study Design
  • 10.2.3. By Sponsor
  • 10.2.4. By Country
• 10.3. South America: Country Analysis
  • 10.3.1. Brazil HIV Clinical Trials Market Outlook
    • 10.3.1.1. Market Size & Forecast
      • 10.3.1.1.1. By Value
    • 10.3.1.2. Market Share & Forecast
      • 10.3.1.2.1. By Phase
      • 10.3.1.2.2. By Study Design
      • 10.3.1.2.3. By Sponsor
  • 10.3.2. Colombia HIV Clinical Trials Market Outlook
    • 10.3.2.1. Market Size & Forecast
      • 10.3.2.1.1. By Value
    • 10.3.2.2. Market Share & Forecast
      • 10.3.2.2.1. By Phase
      • 10.3.2.2.2. By Study Design
      • 10.3.2.2.3. By Sponsor
  • 10.3.3. Argentina HIV Clinical Trials Market Outlook
    • 10.3.3.1. Market Size & Forecast
      • 10.3.3.1.1. By Value
    • 10.3.3.2. Market Share & Forecast
      • 10.3.3.2.1. By Phase
      • 10.3.3.2.2. By Study Design
      • 10.3.3.2.3. By Sponsor

11. Market Dynamics

• 11.1. Drivers
• 11.2. Challenges

12. Market Trends & Developments

• 12.1. Merger & Acquisition (If Any)
• 12.2. Product Launches (If Any)
• 12.3. Recent Developments

13. Global HIV Clinical Trials Market: SWOT Analysis

14. Porter's Five Forces Analysis

• 14.1. Competition in the Industry
• 14.2. Potential of New Entrants
• 14.3. Power of Suppliers
• 14.4. Power of Customers
• 14.5. Threat of Substitute Products

15. Competitive Landscape

• 15.1. PPD Inc
  • 15.1.1. Business Overview
  • 15.1.2. Products & Services
  • 15.1.3. Recent Developments
  • 15.1.4. Key Personnel
  • 15.1.5. SWOT Analysis
• 15.2. IQVIA Inc
• 15.3. PAREXEL International Corp
• 15.4. ICON PLC
• 15.5. Syneos Health Inc
• 15.6. WuXi AppTec Co Ltd
• 15.7. Janssen Global Services LLC
• 15.8. Gilead Sciences Inc
• 15.9. GSK PLC
• 15.10. Charles River Laboratories Inc

16. Strategic Recommendations

17. About Us & Disclaimer