Clesrovimab

12月9日，据美联社报道，美国食品药品监督管理局（FDA）官员已对两种用于保护婴幼儿免受呼吸道合胞病毒（RSV）感染的长效RSV中和抗体药物展开安全审查，即赛诺菲和阿斯利康的Nirsevimab（尼塞韦单抗，商品名Beyfortus）以及默沙东的Clesrovimab（克莱罗韦单抗，商品名Enflonsia）。 虽说这两种长效药物并非疫苗，但此次政府审查正值美国卫生与公众服务部（HHS）部长罗伯特・肯尼迪（RFK, Jr.）领导下，卫生官员和顾问撤回了对常规儿童疫苗接种的建议。可以说，此次审查背后，既有疫苗怀疑论的推动，也牵涉对药物长期安全性的考量。 01 审查背景：FDA为何突然介入婴儿RSV药物？ Beyfortus（2023年FDA获批）与 Enflonsia（2025年6月FDA获批）并非传统疫苗，而是长效抗体药物，通过直接为婴儿提供抗体，快速建立对RSV的保护，尤其适用于早产儿、有基础疾病的高风险婴幼儿。目前FDA尚未批准针对婴儿的RSV疫苗，这两款抗体药物是临床预防RSV重症的“一线选择”。 此次FDA启动安全审查，并非源于明确的安全风险信号，而是与肯尼迪的疫苗怀疑立场密切相关，叠加部分无证据的安全传言发酵。FDA此次审查的直接导火索，是部分疫苗怀疑论者无证据声称“RSV药物可能增加婴儿癫痫风险”，尽管这一说法未得到任何临床数据支持。 肯尼迪认为，许多药品的潜在风险尚未被充分研究。肯尼迪长期持疫苗怀疑论，上任后对多项已获批疫苗和药物的推荐政策进行调整：此前刚推动撤销新生儿乙肝疫苗的常规推荐（尽管专家认为缺乏证据支持），此次RSV药物审查是其质疑现有免疫相关疗法的又一动作。 据相关消息人士和内部文件透露，肯尼迪任命的FDA官员在夏季开始调查RSV疗法。HHS发言人安德鲁·尼克松（Andrew Nixon）告诉路透社，FDA高级顾问特雷西·贝丝·霍格（Tracy Beth Hoeg）早在六月就已向该机构提出安全问题。不过尼克松没有说明促使RSV审查的原因。 知情人士称，霍格在FDA内部的质询促使该机构药品评估与研究中心官员于上周三召开三家制药公司的电话会议，告知他们预计专员办公室将会有更多安全问题。霍格随后被任命为FDA药品评价和研究中心（CDER）代理主任。 在上周五的讨论乙肝疫苗的会议上，霍格引用了四项涉及两种RSV治疗的晚期临床试验数据，称其显示死亡率存在“不利的失衡”，治疗组死亡人数更多。虽然统计学上不显著，意味着这一发现可能只是偶然，但霍格表示委员会“可以重新审视”这个问题。 02 核心争议：安全传言VS临床数据 围绕两款RSV药物的安全争议，本质是“无证据传言”与“扎实临床数据”的对立。FDA审查虽已启动，但药企与现有数据均显示药物安全性可控。 疫苗怀疑论者提出的“RSV药物增加癫痫风险”，目前无任何临床研究或真实世界数据支持。FDA在审查公告中也未提及发现明确安全信号，仅称“基于外部关切启动评估”。事实上，RSV感染本身就可能引发婴儿高热、惊厥，将癫痫风险归咎于预防药物，缺乏科学逻辑支撑。 面对审查，赛诺菲与默沙东均第一时间发声，强调药物安全性经得起验证： 赛诺菲公开表示，Beyfortus已在全球超过50项临床研究中验证安全性，真实世界中已为超 600万婴儿接种，未发现新的安全问题，“目前无任何证据表明药物存在未已知的风险”。 默沙东称已与FDA会面沟通，公司重视监管机构的审查，相信临床数据的严谨性，并表示欢迎继续与监管机构进行科学对话，称其“对Enflonsia的安全性充满信心”。 FDA发言人将此次审查定义为“常规安全评估”，称“若证据支持，可能更新药品说明书”，但未暗示将暂停药物使用。许多科学家和公共卫生专家对此次审查背后的动机表示担忧。他们认为，这是肯尼迪部长基于个人信念而非科学证据，试图系统性地质疑和改变美国既定疫苗与免疫政策的一部分。 斯坦福大学传染病专家Jake Scott教授指出，针对RSV疗法的某些安全性质疑存在方法论缺陷。他警告说，如果基于毫无根据的担忧而撤回这些RSV药物，将“对美国儿童造成伤害”，并可能开创一个危险的先例，即科学咨询体系可能被“垃圾科学”所挟持。 03 结语：平衡风险与获益，科学审慎前行 RSV是婴幼儿最常见且最危险的呼吸道病毒之一。根据联邦估计，每年每100名6个月以下婴儿中有2-3人因RSV住院。对于高风险婴儿，RSV感染可能导致严重的呼吸问题和肺炎，甚至危及生命。 而RSV抗体药物的问世，显著降低了疾病负担。真实世界数据显示，Beyfortus和孕妇RSV疫苗在2024-25季节将婴儿RSV住院率降低了高达43%。 现在的问题是，FDA的审查是否会揭示此前分析未曾忽视的真实安全信号，还是这代表监管机构评估既有预防疗法方式的更根本性转变。制药商正在等待新的数据请求，而更广泛的制药行业也在密切关注，以了解这对未来产品审批意味着什么。 参考资料： [1]US FDA launches fresh safety scrutiny of approved RSV therapies for infants.CNN By Reuters.December 9, 2025. [2]RFK, Jr., Questions Safety of Approved RSV Shots for Babies.SCI AM By Tanya Lewis edited by Claire Cameron.December 9, 2025. [3]FDA Opens Safety Review of Injectable RSV Drugs Approved for Babies and Toddlers.By Associated Press.Dec. 9, 2025, at 5:14 p.m. [4]FDA Takes Another Look at Infant RSV Treatments Amid Growing Safety Questions.MarketDash Editorial Team.December 9, 2025. 识别微信二维码，可添加药时空小编 请注明：姓名+研究方向！

Regulatory decisions once thought settled on protecting infants from respiratory syncytial virus (RSV) are now coming under renewed scrutiny, as the US Health and Human Services (HHS) department under Robert F. Kennedy Jr. pursues its broader rethink of childhood immunisation policy.A spokesperson for HHS confirmed to FirstWord that the FDA's Center for Drug Evaluation and Research (CDER), under newly appointed director Tracy Beth Høeg, is "rigorously reviewing the available data" for RSV therapies such as Sanofi and AstraZeneca's Beyfortus (nirsevimab-alip) and Merck & Co.'s newer Enflonsia (clesrovimab-cfor), both long-acting monoclonal antibodies aimed at protecting young children during their first RSV season."FDA routinely evaluates emerging safety information and will update product labeling if warranted by the totality of the evidence," said HHS press secretary Emily Hilliard in an emailed statement. "CDER's team is rigorously reviewing the available data, as it does for all products, to ensure decisions remain rooted in evidence-based science."Meeting with executivesThe news was first reported Tuesday in Reuters, citing people familiar with the matter who said US health officials had informed executives from the three companies last week that their RSV products would face additional regulatory scrutiny.The report indicates the review traces back several months, when FDA officials appointed under Kennedy – including Høeg, prior to being named CDER director – began quietly pressing for closer examination, starting as early as June.Last week, at a meeting of the CDC's Advisory Committee on Immunization Practices, during which the group dropped a decades-old hepatitis B vaccine guidance for newborns, Høeg pointed to what she described as an "unfavourable imbalance in all-cause mortality" observed across four late-stage RSV trials. In a presentation, she highlighted a slide showing five mortality events each in the Beyfortus arms of the MELODY and MEDLEY trials, and seven and eight, respectively, in the CLEVER and SMART trials of Enflonsia; there were 0, 1, 3 and 4 events, respectively, in the control groups of the trials, according to Høeg's presentation at ACIP.She said the finding was "not quite statistically significant, but yet this is very concerning to see in all four randomised trials, to see that there's actually a higher death rate, and so I think that this is something that could also be revisited by ACIP."A spokesperson for Merck, who confirmed to FirstWord that the company met briefly with FDA representatives last week, said "no deaths [in the CLEVER or SMART trials] were considered by the study investigators to be related to study intervention; no pattern was identified with respect to cause of death or time of death relative to intervention; and deaths were largely attributable to underlying co-morbidities or other identifiable causes."Beyfortus attained blockbuster status in its first full year on the market, with Sanofi reporting sales reaching €1.7 billion ($1.8 billion) in 2024, while Merck expects Enflonsia, which was only approved this past June, to generate about $250 million in sales in 2026, according to the Reuters report. Both are included in the CDC's recommended childhood immunisation schedule.Real-world analysesAn analysis by the CDC earlier this year looked at RSV-associated hospitalisations after the introduction of RSV prevention products. When researchers compared RSV hospitalisations in infants under eight months old during the 2024-25 season with rates seen before the COVID-19 pandemic in two surveillance networks, they found hospital admissions were about 28% and 43% lower.Sanofi boasts even stronger outcomes, citing a real-world study of Beyfortus showing an 87% reduction in RSV-related hospital and doctor visits among immunised infants."At this time, no safety issue has been identified from clinical studies of [Beyfortus] or from post-marketing experience with more than 6 million babies immunised worldwide," a Sanofi spokesperson told FirstWord. "We have extensive safety monitoring processes in place across all our products throughout the entire product lifecycle…Any adverse event case that is reported to Sanofi following the use of our product is tracked in a global safety database, assessed to determine whether the adverse event is related to the product or not, and immediately submitted to FDA and other relevant health authorities. We conduct ongoing safety monitoring not only on an individual case report, but also on aggregated data to investigate any trends in reporting."