美国美国食品药品监督管理局周四宣布，在对罕见血凝块的报告进行最新调查后，现在将限制强生疫苗的授权使用。

尽管血栓的风险仍然非常罕见，但官员们表示，强生疫苗的使用应该受到限制，因为还有其他更安全的选择，包括辉瑞和Moderna的疫苗，它们没有同样的风险。

FDA在一份新闻稿中写道，强生疫苗的使用现在将仅限于其他授权或批准的新冠肺炎疫苗“无法获得或临床适用”的18岁及以上人群，以及选择接受疫苗或否则不会接种的成年人。

FDA表示，该决定是在对一种罕见的血栓形成伴血小板减少综合征(TTS)的报告进行最新分析后做出的。

“我们认识到，让桑·新冠肺炎疫苗在美国和整个国际社会当前的疫情应对中仍有作用。FDA生物制品评估和研究中心主任彼得·马克斯博士在一份声明中写道:“我们的行动反映了我们对注射该疫苗后TTS风险的最新分析，并将疫苗的使用限制在某些个体。”

Marks说，FDA的行动表明了FDA强大的安全监督系统，并补充说该机构致力于做出科学和数据驱动的决定。

“我们一直在密切监测让桑新冠肺炎疫苗及其使用后TTS的发生情况，并使用我们安全监测系统的最新信息来修订EUA。该机构将继续监测让桑新冠肺炎疫苗和所有其他疫苗的安全性，并像在整个疫情一样，将彻底评估新的安全信息，”马克斯说。

罗宾·贝克/法新社

在帕萨迪纳，一名护士正在往注射器里装强生公司的让桑新冠肺炎疫苗.

根据疾病控制和预防中心的数据，迄今为止，已有近1700万美国人接种了强生疫苗。科学家们表示，如果你已经接种了强生疫苗，就没有必要担心，因为血栓的风险会在你接种疫苗后的几天或几周内发生。

然而，健康专家说，如果强生疫苗接种者担心的话，人们应该向他们的医生咨询任何问题。

2021年2月，FDA首次批准强生疫苗用于紧急情况。仅仅两个月后，美国食品和药物管理局和美国疾病控制和预防中心宣布建议暂停接种疫苗，以调查在全国患者中发现的少数TTS病例。

仅仅10天后，暂停就解除了。然而，在12月，在审查了额外的安全性和有效性数据后，CDC的疫苗建议被推荐的在大多数情况下，人们使用疫苗公司Pfizer和Moderna的mRNA疫苗，而不是Johnson & Johnson。

截至3月18日，FDA和CDC已经确认了60例TTS确诊病例，包括9例死亡病例，这表明血凝块是与强生注射液相关的罕见但真实的不良事件。

官员们说，在接种让桑新冠肺炎疫苗后，使个人面临TTS风险的因素仍然未知。

FDA limits J&J COVID-19 vaccine due to rare blood clot risk

The U.S. Food and Drug Administration on Thursday announced it's now limiting the authorized use of the Johnson & Johnson vaccine after conducting an updated investigation into reports of rare blood clots.

Though the risk of blood clots is still extremely rare, officials said use of the Johnson & Johnson vaccine should be limited because there are other, safer options — including vaccines from Pfizer and Moderna — that do not carry the same risk.

Use of the Johnson & Johnson vaccine will now be limited to people ages 18 and older for whom other authorized or approved COVID-19 vaccines are not "accessible or clinically appropriate," and to adults who choose to receive the vaccine or else they would not get vaccinated, the FDA wrote in a press release.

The decision was made after conducting an updated analysis into reports of the rare blood clot condition called thrombosis with thrombocytopenia syndrome, or TTS, the FDA said.

"We recognize that the Janssen COVID-19 vaccine still has a role in the current pandemic response in the United States and across the global community. Our action reflects our updated analysis of the risk of TTS following administration of this vaccine and limits the use of the vaccine to certain individuals,” Dr. Peter Marks, director of the FDA’s Center for Biologics Evaluation and Research, wrote in a statement.

The FDA's action demonstrates the FDA's strong safety surveillance systems, Marks said, adding that the agency is committed to making scientific and data-driven decisions.

"We’ve been closely monitoring the Janssen COVID-19 vaccine and occurrence of TTS following its administration and have used updated information from our safety surveillance systems to revise the EUA. The agency will continue to monitor the safety of the Janssen COVID-19 Vaccine and all other vaccines, and as has been the case throughout the pandemic, will thoroughly evaluate new safety information," Marks said.

To date, nearly 17 million Americans have received the Johnson & Johnson vaccine, according to data from the Centers for Disease Control and Prevention. Scientists said that if you have already received the Johnson & Johnson vaccine, there is no need to be concerned, as the risk of blood clots happens in the days and weeks after you have received your shot.

However, if Johnson & Johnson vaccine recipients are at all concerned, health experts said people should reach out to their doctor with any questions.

The Johnson & Johnson vaccine was first authorized for emergency use by the FDA in February 2021. Just two months later, the FDA and the CDC, announced a recommended pause in the administration of the vaccine to investigate a handful of cases of TTS that had been discovered in patients across the country.

The pause was lifted just 10 days later. However, in December, after reviewing additional safety and efficacy data, the CDC’s vaccine advisoryrecommendedthat people use the mRNA vaccines from vaccine companies Pfizer and Moderna, instead of Johnson & Johnson, in most situations.

Through March 18, the FDA and CDC have identified 60 confirmed cases of TTS, including nine fatal cases, which illustrates that blood clots are a rare but real adverse event associated with the Johnson & Johnson shot.

The factors that put an individual at risk for TTS following administration of Janssen COVID-19 Vaccine remain unknown, officials said.