Come Thursday, the last segment of COBRA enrollees that were eligible for subsidies (those laid off in May 2010) may be in for a jolt. After the subsidy expires, online health insurance provider eHealthInsurance estimates a 186 percent increase in monthly COBRA premiums. Unless they're eligible to enroll in a new employer-based health insurance plan, former subsidy recipients who don't wish to go uninsured may opt to pay their COBRA premiums at the increased rate for an additional three months, until their COBRA eligibility ends. Alternately, they may search for more affordable options in the individual and family health insurance market or through government-sponsored programs.

According to the Kaiser Family Foundation, COBRA coverage without a subsidy is almost three times the cost at $1,137 for a family policy and $410 for an individual, versus $398 and $144 respectively.

Though the subsidy program helped fewer people than expected, experts at the The Commonwealth Fund argue in a new report that coverage without premium assistance is too high for many, who ultimately elect to go without health insurance.

What's more, a "chronically" high unemployment rate is unlikely to improve before 2014, when there will be more health insurance options under the Affordable Care Act.

An estimated 13.9 million Americans are out of work, with an average duration of joblessness of more than 40 weeks, The Commonwealth Fund reports. More than 50 percent of Americans get their health insurance through an employer, and workers who lose their job-based benefits often don't have affordable insurance options; Less than half of states cover adults without children, and many who seek a health plan in the individual market don't end up buying a plan either because they couldn't afford it or they were denied coverage.

Without health benefits, the Commonwealth Fund reports, many go without health care because of the costs. Fifty-two percent of surveyed adults who became uninsured after losing a job with benefits skipped a recommended medical treatment or follow-up test; 50 percent didn't get specialist or other physician care when needed; and 47 percent didn't fill a prescription in the past year.

[See 72% of uninsured skip out on health care]

"Currently, for a majority of Americans, losing a job also means losing health insurance," said Commonwealth Fund Vice President and report co-author Sara Collins. "To make matters worse, once you are unemployed and uninsured, it's nearly impossible to afford COBRA or buy an individual policy. However, when it is fully implemented in 2014, the Affordable Care Act will usher in a new era for the unemployed, who will have a variety of options for comprehensive and affordable health insurance."

More COBRA subsidy coverage from BenefitsPro

• COBRA subsidy falls short
• A brokers' guide to COBRA changes
• COBRA enrollment remains high after subsidy ends
• President OKs COBRA subsidy through May
• Don't go COBRA alone