A study of 138 people with the new coronavirus in China found that 40 percent of them were infected while they were in the hospital—and about a quarter ended up in the intensive care unit. The results, published Friday by the Journal of the American Medical Association, said the in-hospital infections included 17 patients who were already being treated for another illness and 40 health-care workers. About 4 percent of the group died. The study group is the largest so far but barely touches the scope of the outbreak—which has killed more than 600 people and infected 31,000 worldwide.