The six reported cases of blood clots were found in women between the ages of 18 and 48 who received the Johnson & Johnson vaccine. Those with the very rare reaction noticed symptoms between six and 13 days after vaccination. During an Apr. 18 interview with NBC’s Chuck Todd on Meet the Press, Fauci warned that the drug heparin, a blood thinner used to prevent blood clots, could make the situation worse. “The standard way you would think about treating clots is with the anticoagulant heparin,” Fauci said. “That would be contraindicated in this case because heparin could actually make this worse.” And for more on what could cause blood clots, know that If You Take This Medication, You’re More Likely to Get a Blood Clot. “Do not treat patients with thrombotic events and thrombocytopenia following receipt of J&J COVID-19 vaccine with heparin, unless HIT testing is negative,” the Centers for Disease Control and Prevention (CDC) said in an emergency news release on Apr. 13. According to Medscape, HIT testing checks for heparin-induced thrombocytopenia, a clotting condition that comes from treatment with the medication. “If HIT testing is positive or unable to be performed in patient with thrombotic events and thrombocytopenia following receipt of J&J COVID-19 vaccine, non-heparin anticoagulants and high-dose intravenous immune globulin should be strongly considered,” the CDC explains. Other health officials have issued similar warnings. “Giving heparin actually makes things worse,” Peter Marks, MD, director of the Center for Biologics Evaluation and Research with the Food & Drug Administration (FDA), said during an American Medical Association webinar. “One of the individuals who received heparin clearly had complications related to the receipt of heparin.“ae0fcc31ae342fd3a1346ebb1f342fcb And for more COVID news updates sent to you directly, sign up for our daily newsletter. Fauci said the FDA and CDC made the decision to pause use of the vaccine in order to get all the information needed and warn doctors who might see patients, specifically women, who have this unusual reaction. But he doesn’t believe an extension on the Johnson & Johnson vaccine pause will extend past Friday, when he expects the CDC and FDA to make a ruling. “We should have an answer as to where we’re going with it. … There will very likely be a decision,” Fauci said on ABC’s This Week on Apr. 18. “I don’t want to get ahead of them. But I don’t think that they’re going to completely cancel.” And for more on who’s at risk of experiencing another rare event with the vaccine, check out You’re More Likely to Get COVID After Vaccination If You’re Over This Age. While Fauci doesn’t believe the CDC and FDA will advise a cancellation of the Johnson & Johnson vaccine, he does think some changes are afoot. Though he couldn’t say for certain, Fauci imagines either there will be a warning associated with the vaccine or it will be restricted for use among certain people, based on age and maybe sex. “I believe we’ll get back with it and it might be some restrictions. Not sure what that will be, whether they’ll be age or sex or whether they’ll just come back with a warning of some sort,” Fauci said on Meet the Press. “I do think that there will likely be some sort of warning or restriction or risk assessment. I don’t think it’s just going to go back and say, ‘OK, everything’s fine, go right back.’ I think it’ll likely say, ‘OK, we’re going to use it. But be careful under these certain circumstances.’” And for more on who might be most prone to this issue, check out If You Have This Blood Type, You’re More Likely to Get Blood Clots.