The New York Times, April 23, 2021
A panel of advisers to the Centers for Disease Control and Prevention has recommended lifting the pause on the Johnson & Johnson Covid-19 vaccine for all adults while adding a warning label about a rare but dangerous blood clotting disorder. But a central mystery persists: How might a vaccine that has been given to nearly eight million people cause the side effect in just a few of them?
There’s no clear answer yet, but Dr. Andreas Greinacher, a researcher at University Medicine Greifswald in Germany, is leading one effort to find out. At a news conference on Tuesday, he said that he had reached an agreement with Johnson & Johnson to inspect the components of the vaccine to see if it could disrupt the normal blood clotting process under certain rare conditions.
“We just agreed that we would like to work together,” he said.