The US is pausing the Johnson & Johnson coronavirus-vaccine rollout after reports of a rare type of blood clot in six out of 6.8 million people who got the vaccine. All the people affected were women between 18 and 48 years old.

The women developed a type of blood clot known as cerebral venous sinus thrombosis, and they had low levels of blood platelets.

While the adverse event is rare, J&J vaccine recipients may be concerned.

Insider asked Dr. Alex Spyropoulos, an expert on blood clots at Northwell Health in New York, about what you should do if you already got the J&J vaccine.

Take a deep breath and figure out when you got your J&J shot

"No. 1, take a deep breath. No. 2, let that breath out. No. 3, figure out when you got your J&J vaccine. If it's more than about two weeks, then I wouldn't really worry," Spyropoulos said.

That's because the six women who got blood clots developed symptoms six to 13 days after vaccination.

If you got the J&J shot less than 2 to 3 weeks ago, be on the lookout for certain symptoms

A joint statement from the Centers for Disease Control and Prevention and the Food and Drug Administration said if J&J vaccine recipients developed blood-clot symptoms within three weeks of receiving the shot, they should contact their doctor.

But Spyropoulos said you should be in the clear after two weeks.

"If you've gotten your vaccine more than two weeks, you're probably out of the woods and out of the forest," Spyropoulos said.

The symptoms listed in the CDC and FDA statement are:

  • Severe headache.
  • Abdominal pain.
  • Leg pain.
  • Shortness of breath.

Other blood-clot symptoms include:

  • Chest pain.
  • Neurological symptoms, including severe and persistent headaches or blurred vision.

Dr. Vivek Cherian, an internal-medicine physician in Baltimore, said to pay attention to your body post-vaccine.

"Are you developing any of those strokes symptoms – any headaches, visual changes, weakness, difficulty talking, or slurring of your speech? Those are the things that you would want to be aware of and immediately call 911," Cherian said.

If you have blood-clot symptoms, see a doctor

"If there's any kind of worry, go see your physician, and they can easily do a blood test to detect things very quickly," Spyropoulos said.

Christian Mendonca, a J&J vaccine recipient, said he felt discomfort in his knee between weeks two and three of getting the shot, so he scheduled an appointment with an orthopedist.

But after reading the news on Tuesday, he reached out to his primary-care doctor out of caution.

Mendonca's doctor told him to wait until his Friday appointment to see if the knee pain was related to a blood clot, but Mendonca said he suspected the knee pain was related to prior knee issues.

Report vaccine side effects to the CDC

After you get the COVID-19 shot, your body starts to mount an immune response. Common side effects include a sore or swollen arm, headache, fever, chills, fatigue, and nausea – all of which are proof that your immune system is working.

Amid the rollout of coronavirus vaccines, the CDC set up a text-message-based symptom-tracker program called V-safe to measure common side effects and how long they last.

If you've had the vaccine within the past six weeks, you can enroll in the program to report any side effects you've experienced.

This article was originally published by Business Insider.

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