U.S. health officials are weighing next steps as they investigate a handful of unusual blood clots in people who received Johnson & Johnson’s COVID-19 vaccine. The reports are exceedingly rare — so far, six cases out of more than 7 million inoculations. And it’s not clear if they are really linked to the J&J vaccine. European regulators have declared such clots a rare but possible risk with another vaccine that’s made in a similar way, from AstraZeneca. The next phase comes Wednesday, when the Centers for Disease Control and Prevention will debate in a public meeting how to handle the J&J vaccine while authorities investigate.