The number of U.S. residents who lacked health coverage at some point during the year soared to 52 million in 2010, up from 38 million in 2001.

Researchers at the Commonwealth Fund, New York, have published that finding in a summary of results from a survey of 4,005 adults ages 19 and older who live in the continental United States.

Although low-income and moderate-income adults were more likely to be uninsured than higher income adults, researchers found that 13% of the adults in families with annual incomes over 400% of the federal poverty level spent at least some time without health coverage in 2010.

About 57% of the people who lost a job that provided health coverage said they have become uninsured in the last two years, the researchers report.

Only 14% of the survey participants who lost group health coverage used COBRA to continue their coverage, and just 25% said they had been able to find another source of health insurance coverage.

About 71% of the adults who tried to buy individual coverage in the past 3 years said they found it difficult or impossible to find a plan that was affordable, fit their needs, and was willing to offer them coverage at standard rates, the researchers say.

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