The nationwide survey shows that slightly fewer than half of U.S. adults overall say they consider the Johnson & Johnson vaccine very or somewhat safe after its use was halted this month following reports of rare, severe blood clots. The other two coronavirus vaccines authorized for emergency use in the United States, developed by Moderna and Pfizer and its German partner BioNTech, elicit significantly greater public confidence. More than 7 in 10 people say they regard each of those to be very or somewhat safe, the poll finds... Some leading vaccine authorities said the comparatively slender public faith in the Johnson & Johnson shot casts doubt on whether the government’s decision to halt that vaccine was in the best interest of the nation’s health, balancing the dangers of going unvaccinated against the low incidence of the brain blood clots. “If I hear the phrase ‘abundance of caution’ one more time, I’m going to jump out of my window,” said Paul A. Offit, a vaccine expert at Children’s Hospital of Philadelphia. “In the name of transparency, in the name of openness, we scare people.”