vladamir berto, dr. raj singh, are running the study. >> what do you know about the vaccine? safe and there will be no cost to you or your insurance. >> reporter: one of the concerns about the covid vaccine centers around how fast it was developed, taking months instead of years. experts say the shortcuts were not the science, instead, speeding up approvals and distribution. >> i'm truly excited about it. honestly, i'm in awe of what has happened. but there are great reasons for why it's happened so fast. >> reporter: dr. hildreth says in order to rally support in communities of color, it's also important to spotlight the medical professionals behind them. >> messages are fine. you can have wonderful messages. but if the messenger is not trusted, it's not going to be very effective. >> reporter: one of the trusted messengers, reverend liz walker. >> how can you be so certain taking this vaccine is the right choice for you? >> from what i've seen of covid-19, the greater risk is to get sick. so for me, there's no hesitation. >> reporter: walker is an icon in boston. >> i'm lis