The Food and Drug Administration and Centers for Disease Control and Prevention, which issued the guidance, are just beginning their investigations into the reports of potentially dangerous blood clots that occurred in six women in the days after vaccination. Both say the action was taken “out of an abundance of caution,” but that doesn’t answer a lot of questions. Here’s what the agencies have to say about some specific concerns.

I got the J&J vaccine a month (or more) ago. Should I be worried?

Health officials say the risk is very low to people who had the J&J vaccine more than a month ago. Any issues with clotting likely would have presented by now.

I just got a J&J vaccine shot recently. What should I be on alert for?

Again, the odds of developing the clots are low. But CDC Principal Deputy Director Anne Schuchat is suggesting people look for symptoms including severe headache, abdominal pain, leg pain, and shortness of breath. If you develop these within three weeks of getting your J&J shot, contact your health care provider and seek treatment.

She notes, though, that the flu-like symptoms that occur after receiving the vaccine are not things to worry about.

How long will this pause last?

That’s not known precisely right now, but Janet Woodcock, acting FDA commissioner, says “we expect it to be a matter of days.” The CDC says it’s committing to an expeditious review of the available information and an aggressive outreach to physicians so they’ll know how to diagnose, treat, and report issues.

Does this mean I can’t get the J&J COVID vaccine at all now?

No, but it’s probably better to wait. The recommendation is not a mandate, says Dr. Peter Marks, director of the FDA’s center for biologics evaluation and research. “If an individual health care provider has talked with a patient and they determine that the benefit/risk for that patient is appropriate, we’re not going to stop that provider from administering the vaccine.”

That said, expect most mass vaccination sites and pharmacies to follow the advice of the FDA and CDC for now.

I was supposed to get vaccinated this week. What do I do now?

If you have an appointment this week to get the J&J shot, check with your health care provider. Some are already shifting people over to Pfizer or Moderna. Others will reschedule you for another day in the near future, when a Pfizer or Moderna shot is available.

“This may be a bit bumpy,” Schuchat says. “But we do want to make sure people who are scheduled to get vaccinations will be able to get [one] when vaccines are available.”

Are the clots associated with the J&J vaccine fatal?

Of the six cases that have been reported so far, one was fatal and one patient is in critical condition, officials say.

Should I be worried about blood clots with the Moderna or Pfizer vaccine?

The FDA and CDC say there have been no reports of any clotting issues with the other two vaccines being distributed in the U.S. right now. And, to date, there have been over 180 million injections of those, which should allay fears of a similar reaction.

Why did the pause of J&J’s vaccine seemingly come with no warning?

Even the FDA admits this was a sudden action. It comes down to transparency and wanting to prevent possible additional cases.

“I wish we had more time to get everyone prepared and this could have gone even more smoothly,” Woodcock says. “As we learned about the issue…it was clear to us that we needed to alert the public…The decision was based on events that might occur between when we made that realization and when we got the word out.”

What about the European rollout of J&J’s vaccine?

Johnson & Johnson announced Tuesday that it would be proactively delaying the rollout of the vaccine in Europe and would review the cases with European health authorities.