The post-vaccination blood clotting and low blood platelet levels seen in a small number of people who received the Johnson & Johnson COVID-19 vaccine has not been seen in any Americans who got shots from Pfizer or Moderna, a U.S. official said Tuesday. Dr. Peter Marks, director of the Food and Drug Administration’s Center for Biologics Evaluation and Research, told reporters on a call that “at this time, we’ve not found any reports of cerebral venous sinus thrombosis combined with thrombocytopenia” among those who received a Pfizer or Moderna shot. U.S. health officials and drug regulators earlier in the day recommended a pause in the administration of Johnson & Johnson’s COVID-19 shot because of six reported post-vaccination cases of cerebral venous sinus thrombosis, a rare type of blood clotting that requires an atypical treatment. Moderna said that they performed an assessment of people who got their shot found no association with the blood clots. …