COVID-19 hospitalizations at Yale New Haven Health’s five hospitals have dropped 27% over the past 10 days, Marna Borgstrom, the system’s president and chief executive officer, reported Monday. The number of patients fell from 194 on April 23 to 142 on Monday, a “very good sign” that the disease is declining in Connecticut though it’s still “a little premature ... to say we’re coming out of this,” Borgstrom said during a virtual press briefing. With COVID-19 vaccination appointments going unfilled, Yale New Haven Health officials said they would continue to accept walk-up patients at mass vaccination sites such as the one in Mohegan Sun’s Earth Expo & Convention Center. If demand for vaccinations continues to fall well short of supply, the sites may begin operating fewer days per week, but there are no plans to close any of them, Dr. Thomas Balcezak, Yale New Haven Health’s chief clinical officer, said.