The US Centers for Disease Control and Prevention and the US Food and Drug Administration are recommending that the United States pause the use of Johnson & Johnson's Covid-19 vaccine over six reported US cases of a "rare and severe" type of blood clot. The six reported cases were among more than 6.8 million doses of the Johnson & Johnson vaccine administered in the United States. All six cases occurred among women ages of 18 and 48, and symptoms occurred 6 to 13 days after vaccination, according to a joint statement on Tuesday from Dr. Anne Schuchat, principal deputy director of the CDC and Dr. Peter Marks, director of the FDA's Center for Biologics Evaluation and Research.