Last year, the flu killed more than 300 people in California and sickened thousands more.
To help combat the spread of the virus, the state provides thousands of doses of the flu vaccine every year to county health departments. It's part of a big public health campaign to vaccinate thousands of San Diegans this year.
NBC 7 Investigates looked at how many vaccine doses actually make it to the public and found a lot of waste and very little oversight. The investigation found, compared to other counties across the state, San Diego does a relatively good job using its vaccine supply.
Over the last five years the county used 87 percent of the vaccine it ordered, ranking 22nd among the 61 counties and big cities in the state, according to the data. Alameda County, in the Bay Area, ranks number one, using almost 99 percent of its vaccine.
But not all counties appear to be as proactive.
NBC 7 Investigates reviewed the past five years of vaccine usage data from the California Department of Public Health. According to the data, on average, more than 88,000 vaccine doses go unused each year.
The state provides the flu vaccine free to all county health departments. The distribution is based on projected need, but the flu vaccine is only good for one season before it expires.
State records reveal a wide range of vaccine usage, from an average of 99 percent in Alameda to 84 percent in Imperial County to just 61 percent in Calaveras.
Dr. Robyn Gershon, an epidemiologist at the University of California San Francisco, said all counties should have an effective system for distributing vaccines, not only for the flu, but also because it’s the practice for any outbreak.
"This certainly is a great trial run for us to really ramp up if and when we need to,” Gershon said. “So, let’s hope to get this right; we need to get this right.”
While all counties are required to report their numbers to the state, NBC 7 Investigates found none of the counties we spoke with had any idea how they compared and there's virtually no oversight from the state.
“We don’t want to waste taxpayers money by having vaccine go to waste,” Gershon said.
At $11.26 a dose, unused vaccine has cost taxpayers at least $5.9 million in the past five years.
The state health department declined NBC's request for an interview. But after our station group started asking for data, the state began requiring counties to report their vaccine usage rates in order to better track the numbers.
With the Ebola virus now making headlines and researchers scrambling to formulate a vaccine, Gershon said it’s more important than ever for public health agencies to be prepared.
“If we were to have a vaccine and need to get it out to the entire population quickly, this influenza program is the model,” she said.
The state said it is working with county health departments to promote the flu vaccine and to share best practices between counties.