first 45 volunteers who rolled up their sleeves back in March. Sure enough, the vaccine provided a hoped-for immune boost.Those early volunteers developed what are called neutralizing antibodies in their bloodstream -- molecules key to blocking infection -- at levels comparable to those found in people who survived COVID-19, the research team reported in the New England Journal of Medicine.“This is an essential building block that is needed to move forward with the trials that could actually determine whether the vaccine does protect against infection,” said Dr.