联邦政府的健康周二，在六人出现凝血障碍的报道后，官员们下令暂时停止使用强生公司生产的新冠肺炎疫苗。

疾病控制和预防中心和食品药品监督管理局在一份声明中说联合声明这些机构“建议暂停”,同时收集和审查更多关于单次注射疫苗的数据。

根据美国疾病预防控制中心的数据，美国有近700万人接受了J&J注射，另有约900万份被分发以备将来使用。

到目前为止，还没有报道与辉瑞或莫德纳有关的凝血病例疫苗但是如果你已经接种了J&J单剂量疫苗，并且担心潜在的副作用，你需要知道的是。

如果你是这些人中的一员，并且担心潜在的副作用，下面是你需要知道的。

凝血?我需要担心吗?

迄今为止，仅报告了6例病例，均为18至48岁的妇女。

“我认为人们不应该惊慌，”威廉·沙夫纳博士纳什维尔范德比尔特大学预防医学和传染病教授告诉美国广播公司。"目前，这是一个有待进一步调查的关联."

根据推断，这个非常有限的数据集显示，一个人出现类似并发症的几率——至少到目前为止——不到百万分之一。又一个研究据估计，大约有六分之一的新冠肺炎住院患者出现了某种凝血现象。

帕特里克·法伦/法新社，通过盖蒂图像，文件

一个注射器里装了一剂强生让桑新冠肺炎疫苗

在接受过J&J疫苗的个体中可以看到脑静脉窦血栓形成或CVST，以及低血小板计数。CVST很少见在脑部引流静脉窦中可以看到。它通常与怀孕、罕见的凝血障碍和激素避孕有关。

我打了J&J疫苗，有点头痛。现在我该担心吗?

打针后几个小时甚至几天内出现头痛通常是一种常见的副作用——不是一个严重的问题。

头痛“更有可能来自一个更常见的实体...就像疫苗的副作用一样托德·埃勒林博士他是哈佛医学院的讲师，也是波士顿南岸医疗中心的传染病医生..

在强生公司2021年2月简报对于美国食品和药物管理局来说，疫苗最常见的副作用之一是头痛。但是，正如埃勒林指出的那样，如果你“出现持续性头痛或胸痛，或呼吸急促或腹痛”，你应该提醒医疗保健专业人员。

医学专业人士表示，与这种类型的血液凝固相关的症状将是严重的，正如埃勒林指出的那样，如果您“出现持续性头痛或胸痛，或呼吸急促或腹痛”，您应该提醒医疗保健专业人员。

马克·罗尔斯顿/法新社，通过盖蒂图像，文件

2019年8月28日，强生校园的入口标志显示了他们在加州欧文的标志。

‘正常’副作用和吸出血块有什么区别?

疫苗副作用通常在注射后的24至48小时内感觉到。专家说，如果你在最初几天之外感觉到了严重或持续的新副作用，请联系医生。

与人们在接种疫苗后经历的典型流感样症状不同，这“应该是可区分的”疾控中心主任罗谢尔·瓦伦斯基博士在周二与各州州长的电话会议上说。“这些病例中的每一个都是在六天或六天之后出现的。...我们所说的是在6到13天的时间里出现的严重头痛。”

专家们一再强调疫苗绝对安全，但确实建议密切关注你的感受。“任何在运动、力量上感觉不同的东西，都是身体一侧与另一侧不对称的，”格拉德斯通研究所(Gladstone Institutes)主席、心脏病学家迪帕克·斯里瓦斯塔瓦(Deepak Srivastava)博士告诉美国广播公司(ABC News)。“但这是如此罕见的事件，我不想让数百万人感到震惊。”

我应该服用什么药物来预防血栓吗?

专家们同意，没有理由服用止痛药或做任何其他事情来降低你的风险，因为它已经很小了。

“如果你没有任何症状，就没有预防措施可以采取，”他说劳拉·芬恩博士奥切斯纳健康中心血液学和骨髓移植主任。事实上，芬恩说，在FDA和CDC确定是什么导致了罕见的凝血事件之前，最好避免服用阿司匹林等止痛药。

香农·斯台普顿/路透社，文件

强生公司的新冠肺炎疫苗可以在诺思韦尔健康中心的南岸大学看到

为什么美国食品和药物管理局和疾病预防控制中心现在告诉我们这些，接下来呢?

接受美国广播公司采访的专家称赞美国食品和药物管理局和美国疾病预防控制中心对潜在的安全问题保持透明。

接下来，疾控中心将召集其外部咨询委员会，调查是否存在真正的联系，并提出建议。

食品和药物管理局代理专员珍妮特·伍德库克博士称美国人可以期待“几天内”的更新

“当它是有关的，”说Jennifer Haythe博士医学副教授、哥伦比亚妇女心脏中心联合主任和心脏病重症监护室专家说，“它仍然绝对安全。”

如果有人接受了J&J刺拳，并感觉到“任何中风症状——视力模糊、说话困难、手臂或腿无力、昏厥或失去知觉”，他们应该立即打电话给医生或911。

虽然心血管疾病的这种特殊情况很少发生——同样，不到百万分之一的疫苗接受者——但心血管疾病是许多美国人每天摄入的药物的风险:口服避孕药。

“口服避孕药疗法是CVST的一个已知风险因素，”芬恩说。“这种类型的血块按部位分类实际上很少见，但女性比男性更容易出现。”

Worried about your J&J COVID vaccine as shots are paused? Don't be, experts say.

Federalhealthofficials on Tuesday ordered a temporary stop on administering COVID-19 vaccine produced by Johnson & Johnson after reports of six people experiencing a blood clotting disorder.

The Centers for Disease Control and Prevention and the Food and Drug Administration said in ajoint statementthe agencies were "recommending a pause" while more data pertaining to the single-shot vaccine is collected and reviewed.

Nearly 7 million people in the U.S. have received J&J shots, and roughly 9 million more doses have been distributed for future use, according to CDC data.

There have been no blood clotting cases reported so far tied to the Pfizer or Modernavaccines, but if you've received the J&J single-dose vaccine -- and are concerned over potential side effects -- here's what you need to know.

If you're one of those individuals -- and concerned over potential side effects -- here's what you need to know.

Clotting? Do I need to be worried?

To date, only six cases have been reported -- all women, aged 18 to 48.

"I don't think people should be alarmed,"Dr. William Schaffner, a professor of preventative medicine and infectious diseases at Vanderbilt University in Nashville, told ABC. "This is -- at the moment -- an association that is going to be further investigated."

Extrapolated, that very limited data set shows that a person's odds -- at least so far -- of similar complications are less than 1 in 1 million. Anotherstudyestimated that roughly 1 in 6 people hospitalized with COVID-19 experienced some kind of clotting.

Cerebral venous sinus thrombosis, or CVST, and low platelet counts were seen in individuals who've received the J&J vaccine.CVST is rareand seen in the draining venous sinuses of the brain. It's often associated with pregnancy, rare clotting disorders and hormonal contraception.

I got the J&J vaccine and have a headache. Now should I be worried?

Experiencing a headache within a few hours, or even days, after getting the shot is often a common side effect -- not a serious issue.

Headaches are "much more likely to be from a more common entity ... like a vaccine side effect," saidDr. Todd Ellerin, an instructor at Harvard Medical School and an infectious disease doctor at Boston's South Shore Medical Center..

In Johnson & Johnson'sFebruary 2021 briefingwith the FDA, one of the most commonly reported adverse effects to the vaccine was headache. But, as Ellerin noted, you should alert a health care professional if you "develop persistent headaches or chest pain, or shortness of breath or abdominal pain."

Medical professionals said symptoms associated with this type of blood clotting will be severe, and, as Ellerin noted, you should alert a health care professional if you "develop persistent headaches or chest pain, or shortness of breath or abdominal pain."

What's the difference between 'normal' side effects and blot clots?

Vaccine side effects typically are felt within the first 24 to 48 hours after receiving a shot. If you're feeling what may be a severe or persistent new side effect outside of those first few days, contact a doctor, experts said.

Unlike the typical flu-like symptoms people experience after the vaccine, this "should be distinguishable,"CDC Director Dr. Rochelle Walenskysaid on a call Tuesday with state governors. "Every one of these cases have presented at or after six days. ... What we're talking about is severe headaches that occur in the six-to-13-day period."

Experts time and again have emphasized that vaccines are overwhelmingly safe, but did advise keeping tabs on how you're feeling -- "anything that feels different in movements, strength, that's asymmetric on one side of the body vs. another," Dr. Deepak Srivastava, president of the Gladstone Institutes and a cardiologist, told ABC News. "But it's such a rare event that I wouldn't want millions of people to be alarmed."

Should I take any medication to prevent clots?

There's no reason to take painkillers or do anything else to reduce your risk because it's already so small, experts agreed.

"If you're not having any symptoms, there isn't a prophylactic measure to take," saidDr. Laura Finn, director of hematology and bone marrow transplant at Ochsner Health. In fact, Finn said it's best to avoid painkillers like aspirin until the FDA and CDC determine what caused the rare clotting events.

Why are the FDA and CDC telling us about this now -- and what's next?

Experts interviewed by ABC News applauded the FDA and CDC for being transparent about a potential safety concern.

Next, the CDC will convene its outside advisory committee to investigate whether there's a true link and offer recommendations.

FDA acting CommissionerDr. Janet Woodcocksaid Americans can expect an update in "a matter of days."

"While it's concerning," saidDr. Jennifer Haythe, an associate professor of medicine, co-director of Columbia Women's Heart Center and a critical care cardiologist, "it's still overwhelmingly safe."

Should someone who's received the J&J jab feel "any symptoms of stroke -- blurry vision, difficulty talking, loss of strength in your arms or legs, fainting or loss of consciousness," they should call a doctor or 911 immediately.

While this specific instance of CVST has been rare -- again, fewer than 1 in 1 million vaccine recipients -- CVST is a risk of medication many Americans ingest daily: oral contraceptives.

"Oral contraceptive therapy is a known risk factor for CVST," Finn said. "This type of blood clot by location is actually rare, but it is more likely to occur in women than in men."