Transcript for US urges a pause of Johnson & Johnson vaccinations, after people get blood clots
Good evening and it's great to have you with us here on this Tuesday night. And we begin tonight with that move to halt the Johnson & Johnson one-shot vaccine in this country. The CDC and the fda temporarily suspending its use out of an abundance of caution, in their words, as they now investigate those six cases of a rare blood clot in women. Authorities underscore this is rare. Six cases out of nearly 7 million doses already given of this particular vaccine. The news came early today from the CDC and the fda, halting those injections of the Johnson & Johnson vingle shot at federal sites. At least 48 states tonight are now following suit. Wagreens and CVS halting those shots, too. Many people alerted that their appointments have been canceled. Those pharmacies say they will reschedule. Some locations offering one of the other vaccines from pfizer or modern. Dr. Anthony fuci defending the pause tonight. But tonight, some governors are angry this has been halted. And what do you do if you've already had the Johnson & Johnson vaccine in a list of symptoms to be aware of tonight. And what if you've already scheduled an appointment for this particular vaccine? We're going to ask Dr. Jha about all of this in a moment. But first, ABC's Steve osunsami leads us off from the CDC in Atlanta. Reporter: It's the covid vaccine that promises good protection with a single dose. An important tool for public health officials around the world, but tonight, the fda is telling everyone to hold off using the Johnson & Johnson vaccine. A very small number of women have come down with an extremely rarely blood clot after getting the shot. This is a really rare event. If you look at what we know so far, there have been six out of the 6.85 million doses, which is less than one in a million. Reporter: All six women were between 18 and 48 years old. They got sick about 6 to 13 days after getting vaccinated. The clots formed in veins of the sinus and prevented blood from draining out of the brain. One woman died, another in critical condition. There's no evidence showing the vaccine caused the condition, and to be super clear, your chances of getting struck by lightning are nearly twice as high. One in half a million. But the fda is warning anyone who got the Johnson & Johnson vaccine in the last three weeks to be on the lookout for severe headache, shortness of breath, abdominal or leg pain. And if you need treatment for a blood clot, they strongly suggest avoiding the commonly used blood thinner heparin, which they believe adds to the complications. That would be a mistake in this situation, because it could be dangerous and make the situation much worse. Reporter: Health officials say that these rare immune responses have only been seen in viral vector vaccines. Johnson & Johnson is one. Astrazeneca is another. Pfizer and modern use a different technology. Very quickly today, the federal government put a hold on using the shot at mass vaccination sites and at least 48 states followed. The nation's governors tonight are beyond frustrated. In a phone call with the white house, they questioned the wisdom of putting a hold on a vaccine over such small number of cases. The ability for governors to reinstill confidence after something like this is a hundred times harder than putting the pause on in the first place. Reporter: People who've already gotten the shot are worried and now there's more of a scramble. CVS and Walgreens, for example, are rescheduling their Johnson & Johnson appointments. I don't want to take any chances. It's my body and I want to be safe. Reporter: The president tonight is trying to reassure Americans that there will still be enough vaccine from moderna and pfizer. Late today, pfizer announced that they now expect to deliver their 300 million doses about two weeks ahead of schedule. There's enough vaccine that is basically 100% unqutionable for every single solitary American. And Steve osunsami joins us tonight from the CDC and Steve, what are we hearing so far from authorities on this? How long do we,% this temporary pause of the Johnson & Johnson vaccine to last? Reporter: Well, David, federal health officials were asked that same question by the nation's governors today and the answer was days, possibly weeks, hopefully not months. There's a public hearing on this issue tomorrow, they're encouraging anyone with those symptoms to call their doctor. And one criticism that we're hearing from people who are upset with the governmentgovernment's response to this is that it's really hard to scare Americans and then later on try to unscare them. David? All right, Steve osunsami leading us off tonight. Steve, thank you.
This transcript has been automatically generated and may not be 100% accurate.