In a research letter published online in this week’s Journal of the American Medical Association, Boston Medical Center researchers called 943 pharmacies in five big cities across the country and found that 80 percent of the stores kept Plan B in stock - which is a higher percentage than in older studies - but that callers posing as teens were often given misinformation. Some 19 percent of the time, callers who said they were 17 and wanted to get Plan B were told briskly by pharmacy employees that they couldn’t have it.