WASHINGTON—Health insurance companies can no longer drop policyholders when they get sick, can’t refuse to cover kids with pre-existing medical conditions, and aren’t allowed to decide which doctors patients can go to.

Despite this, Lesa Kentner of Franklin, who has a son in college, said she had concerns about the new law.

“My husband has a good job with good health benefits,” Kentner said Thursday. “(Our son) is covered under that as long as he’s a full-time student. But the company is small, it is literally a family business. Our country is made of so many of these small family businesses. Can they really take on that financial burden?”

The new law, which took effect Thursday, stipulates that young adults will be allowed to remain on their parent’s health insurance plan until their 26th birthday, unless they are offered coverage at work. It would not matter if the young adult lives with their parents, are a dependent on their parent’s tax return, are a student or are married.

“While there were vigorous debates preceding the passage of the Affordable Care Act, the bill is now law,” U.S. Sen. Jim Webb (D-Va.) said Wednesday. “It is important for Virginians to know about the new protections and benefits provided by the law.”

Webb’s office estimates 25,800 young adults in Virginia would qualify for the extension. Kentner said that despite her reservation, she thinks the change for young adults is a good idea.

“I just don’t want a federally mandated system put in place to take care of me,” she said.

Under the new law, insurers will give individuals affected by the Medicare Part D coverage gap — also called the “donut hole” — a $250 rebate to help seniors pay for prescription drugs. Fifty percent of the coverage gap, which affects early retirees not yet eligible for Medicare, will be closed in 2011. The other half of the coverage gap will be closed by 2020.

Insurers are also prohibited from excluding coverage for children under the age of 19 who have a pre-existing medical condition. The law will change again in 2014 prohibiting such exclusions at any age.

Health insurance providers will also be required to implement a coverage appeals process.

“Before reform, when insurers denied patients coverage or restricted treatment, they were left with few options to appeal,” Webb’s office said. “Starting (Thursday), if individuals purchase or join a new policy, they will be guaranteed the right to appeal insurance company decisions to an independent third party.”

The new law will also ban insurance companies from cutting coverage for people who make unintentional paperwork mistakes, or from implementing a lifetime limit on the amount of coverage they provide.

Also, under certain plans, preventive care services such as mammograms, colonoscopies, immunizations, pre-natal and new baby care will be covered. Insurance companies will be prohibited from charging deductibles, co-payments or co-insurance for them.

The new law will also:

• Prohibit insurers from charging co-payments or deductibles for Level A or B preventive care and medical screenings on all new insurance plans.

• Restrict insurers from enforcing annual spending caps, which will be eliminated by 2014.

• Require insurers to disclose administrative and executive expenses.