The US health authorities simply warned of a blood clotting risk from Johnson & Johnson’s Covid-19 vaccine, but decided to pause use out of concern that doctors might be treating the condition incorrectly, people familiar with the matter said.
Over the past four weeks, US health officials have been alarmed about similar blood clotting conditions in Europe involving a Covid-19 vaccine from AstraZeneca PLC, the people said. The officials dug into a US vaccine safety database and identified the cases of major concern, but discussed what action to take.
Last Monday evening, officials decided urgent action needed to be taken, the people said. According to the U.S. Centers for Disease Control and Prevention, four of the six women in the U.S. who developed the blood clots days after vaccination were initially given heparin. Its use could have worsened the patients’ condition, the people said.
That night, at a one-hour Zoom meeting, the country’s top health officials agreed to take the strongest step: publicly recommending pausing the use of the vaccine while investigating adverse events, the people said.
Since the announcement, the Food and Drug Administration has studied other reports of additional cases of blood clotting among people who received J & J’s vaccine, but it has not confirmed whether they reflect the same phenomenon, the people said. Still, officials are increasingly convinced, people added, that the six total cases reported so far are related to the shot.