Teams are preparing for the vaccinations between Christmas and New Year.
And two more GP-led community sites will start vaccinating those ages over 80 and health care staff.
Dave Partlow, Somerset County Council's (SCC) strategic manager for adult social care, said they "cannot wait" to start the vaccinations.
"We are starting with larger homes that care for people with dementia because higher rates of COVID-19 can occur in these homes where it is more difficult to contain," he said.
"However, I want to be really clear with our message to all other care homes – this is just the start of our vaccination programme and we will come to you as soon as possible.”