LOS ANGELES, Dec. 16 (UPI) -- Nearly one-fifth of all Californians under age 65 were without health insurance for all or some of 2007, researchers said.

Using data from the California Health Interview Survey, researchers at the University of California, Los Angeles, Center for Health Policy Research found that 6.4 million Californians lacked any health insurance coverage for all or some of 2007, or 19.5 percent of all Californians under age 65.

Lead author E. Richard Brown said this is slightly lower than the uninsured rate of 20.2 percent in 2005; however, the gains were small and are now likely to be reversed by the current recession.

"We're looking at the final year of an economic expansion and yet the gains in coverage were small," Brown said in a statement. "If the employer-based system can't increase health insurance in good times, how will they do it in bad? The answer is: they can't. Only comprehensive health care reform will change the equation."

In 2003, the state's unemployment rate rose to 6.8 percent, which was a main driver of the decline in employment-based insurance from 56.4 percent in 2001 to 53.8 percent in 2003, the policy brief said. Today in California, the statewide unemployment rate is more than 8 percent and is predicted to rise, Brown said.

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