Design of vaccine efficacy trials during public health emergencies  
	
	
    
	        
		
        03 Jul 2019  
	
	
      
		
  
  Public health emergencies, such as an Ebola disease outbreak, provide a complex and challenging environment for the evaluation of candidate vaccines. Here, we outline the need for flexible and responsive vaccine trial designs to be used in public health emergencies, and we summarize recommendations for their use in this setting.