Blood-clot issues surrounding Johnson & Johnson’s Covid-19 vaccine could complicate the U.S. mass vaccination campaign, deterring people who are already hesitant and giving room for misinformation to spread, health experts said. Concerns that the blood-clot issue will raise vaccine doubts led the federal government to step up efforts to educate people about the rare but serious blood clots and authorities’ recommendation to pause use of J&J’s shot while the reports are investigated, Anthony Fauci, the government’s top infectious disease expert, said Wednesday. The U.S. Food and Drug Administration and U.S. Centers for Disease Control and Prevention issued the recommendation Monday, after reports that six women ages 18 to 48 developed blood clots and low-platelet counts following vaccination, and one of them died. More than 6.8 million doses of J&J’s shot have been administered in the U.S. To read the full story.