Food and Drug Administration scientists found potential benefit to a second dose of the Johnson & Johnson coronavirus vaccine in a data review that was released Wednesday and that depended heavily on the company’s analysis, suggesting a booster of that shot was perhaps more warranted than additional doses of other coronavirus inoculations. From the dawn of the vaccine campaign, many experts said they believed the one-shot Johnson & Johnson regimen would ultimately require a second shot, and the documents pave the way for a panel of experts who advise the FDA to discuss Friday the timing, necessity and safety of...