U.S. health officials are calling for an immediate pause in the use of Johnson & Johnson’s single-dose COVID-19 vaccine, after six recipients developed a rare complication from blood clots within two weeks of their vaccinations. One woman died, and another has been hospitalized in critical condition. It’s not known if the vaccine caused the disorders. The Centers for Disease Control and Prevention reports as many as 100,000 people regularly die of blood clots each year, and clotting is often a symptom of COVID-19.

On Monday, the U.S. recorded 70,000 new cases as the nation’s COVID-19 death toll passed 562,000. The CDC reports 120 million U.S. residents have received at least one dose of a vaccine.