Just over a quarter of long-term care facilities surveyed recently in Maine said less than half of staffers are willing to get the coronavirus vaccine, a trend that could hamper efforts to prevent deadly outbreaks as vulnerable residents overwhelmingly accept the shots. The Maine Medical Directors Association, which represents nursing home directors, surveyed 63 skilled nursing homes, assisted living facilities and other places in the first phase of Maine’s vaccine program over a 10-day period ending Tuesday.