Refrigerator malfunctions and potential contamination have left shots for the flu, HPV and polio ineffective, meaning thousands have been sent letters asking to return to be revaccinated.
Vaccines have become a hot button issue over the last several weeks.
Measles outbreaks in anti-vaccination 'hot spots' have sprouted up across the US, affecting 10 states.
Health officials in one of the states most affected, Washington, say demand for the measles vaccine has soared by 500 percent compared to last year.
However, as people have rushed to inoculate themselves against all diseases, health officials say they may have received compromised vaccines that weren't stored properly.
Issues at clinics in California, Indiana, Kentucky and Ohio have affected nearly 25,000 patients, reported Kaiser Health News.
It's raised concerns about vaccine oversight - or lack thereof - at many medical offices.
Nearly 25,000 patients in California, Indiana, Kentucky and Ohio received vaccines that were not properly stored. Pictured: Refrigerated vaccines stored at Kaiser Permanente East Medical offices in Denver, February 2015
In October 2017, health officials in Ventura County in California were worried that vaccines were getting to room temperature by the time they reached clinics, reported the Ventura County Star.
The Centers for Disease Control and Prevention (CDC) recommends that shots be stored between 35F and 46F in a refrigerator and between -58F and 5F in a freez
The Ventura Health Care Agency decided to fix the problem by transporting the vaccines on ice packs.
However, during a standard November audit, the officials discovered that the ice packs had frozen some of the vaccines, potentially lowering their efficacy, Kaise Health News reported.
According to the Los Angeles Times, about 25 types of vaccines may have been affected. This includes the flu shot and the human papillomavirus vaccines.
The Ventura Health Care Agency offered to re-vaccinate anyone who had received one of the affected shots: about 23,000 patients.
And
