The rate has more than doubled in just the past two weeks.
"We went from 23% of our daily doses being booster shots to about 52% this week," said Joe Prado, Fresno County Department of Public Health interim assistant director.
They are numbers for the local health department, which allocates vaccines to more than 107 medical providers in the county.
Some Valley residents have reported challenges with getting booster shots, including canceled appointments.
However, according to Fresno County health officials, there are enough doses for everyone.
"In the past 30 days, we've redistributed from our freezers about 17,000 doses," Prado said.
Prado added the department tries to keep at least 10,000 doses in the freezer to help supplement medical providers, plus some local pharmacies, which receive most of their vaccines from the federal allocation.
"We're a quick relief valve for them," he said. "We got our freezer stocked for them, so we've seen some pharmacies transition to working with us as well."
While booster numbers are on the rise, local health officials are still pushing for those five years and older to get their first dose.
According to Fresno County data, 65% of eligible residents have at least one dose.
Prado said he'd like to see that number increase to at least 70% by the end of the holidays to help keep more people out of the hospital.
"We saw a significant decrease in our 65 and over population, when we got them vaccinated at 70%, you saw that population present less in our emergency rooms with COVID symptoms," he said.
Appointments can be booked for both the initial vaccine and booster shot on myturn.ca.gov.