The US rollout of Johnson & Johnson’s single-dose Covid-19 vaccine was halted Tuesday as regulators race to investigate rare blood-clotting complications linked to the shot. The move may force thousands of people scheduled to receive the shot this week to scramble for an alternative.
Both the Food and Drug Administration and the Centers for Disease Control and Prevention recommended a pause in distributing the vaccine after six reported cases of cerebral venous sinus thrombosis (CVST). These clots block blood flowing out of the brain and can quickly turn deadly.
The complications were found in women between the ages of 18 and 48, and they arose between six and 13 days after receiving the Johnson & Johnson vaccine. “Of the clots seen in the United States, one case was fatal, and one patient is in critical condition,” said Peter Marks, the head of the FDA’s Center for Biologics Evaluation and Research, during a Tuesday press conference.
However, the fact that so few cases led to a nationwide pause of the vaccine has raised questions about a possible overreaction.