COLUMBIAÂ â The Columbia/Boone County Department of Public Health and Human Services is training volunteers for a new vaccine ambassador program. The vaccine ambassadors will provide community outreach in neighborhoods with a community based vaccination clinic. The health department is working with the Boone County Clerk's Office to bring mobile vaccination clinics to neighborhoods who may have barriers that make it inaccessible to get the vaccine. "We're focusing on breaking down those barriers and making sure that vaccine is as accessible as possible," Sara Humm, Columbia/Boone County PHHS Information Specialist, said. "We have a mobile unit that will be headed out this weekend, that will be at five different locations throughout the county on Saturday."