One of four working-age U.S. adults experienced a gap in health insurance coverage during 2011, often because they lost or changed jobs, according to a new Commonwealth Fund study released today.

About seven of 10 survey respondents who went through a period without health insurance lacked coverage for a year or longer. More than half were uninsured for two years or more, according to the 2011 Commonwealth Fund Health Insurance Tracking Survey of U.S. Adults.

Major provisions in the Patient Protection and Affordable Care Act that will go into effect starting in 2014 are expected to help bridge coverage gaps and make insurance more affordable, according to the study’s authors. These include an expansion in eligibility for Medicaid, subsidies for purchasing private plans through new health insurance exchanges, and rules preventing insurers from denying coverage or charging more based on gender or a preexisting condition.